Abstract
Marine oomycetous species produce, among other fatty acids, omega-6 arachidonic acid (ARA) and omega-3 eicosapentaenoic acid (EPA), with implications for the industrial potential of this group of organisms and the need to find an isolate with high production. This study screened 14 isolates of marine oomycetous species: Halophytophthora avicenniae, H. batemanensis, H. exoprolifera, H. polymorphica and Salispina spinosa cultured from fallen mangrove leaves in Taiwan for 24 saturated and unsaturated fatty acids in their mycelia. This paper is the first to report C18:1n-7 vaccenic acid, C20:1 eicosenoic acid, C24:1 nervonic acid, C20:2n-6 eicosadienoic acid, C22:4n-6 adrenic acid, C20:4n-3 eicosatetraenoic acid and C22:5n-3 docosapentaenoic acid in mycelia of Halophytophthora and Salispina species, and the fatty acid profiles of H. batemanensis and H. exoprolifera. Five fatty acids were dominant in the mycelia of the isolates, i.e. C16:0 palmitic acid, C18:1n-9 oleic acid, C18:2n-6 linoleic acid, C20:4n-6 arachidonic acid and C20:5n-3 eicosapentaenoic acid. For the essential fatty acids, S. spinosa produced the highest level of arachidonic acid (27–31% of total fatty acid (TFA), 141–188 mg l−1 yield) while H. avicenniae IMB212 produced the highest percentage of EPA (15% of TFA) while H. polymorphica IMB227 produced the highest yield (96 mg l−1). Different species and isolates of the same species produced different fatty acid profiles, and further research effort may yield a high production isolate of industrial significance and also important fatty acids from the marine environment.
1 Introduction
Halophytophthora is an aquatic oomycetous genus, and includes both freshwater and marine species: H. avicenniae, H. batemanensis, H. exoprolifera, H. fluviatilis, H. insularis, H. masteri, H. polymorphica, H. porrigovesica, H. souzae and H. vesicula (Jesus et al. 2019; Marano et al. 2014; Yang and Hong 2014). Salispina, is a related genus and was established to accommodate two subspecies of Halophytophthora spinosa (var. spinosa and var. lobata) (Li et al. 2016). Salispina currently includes S. hoi, S. intermedia, S. lobata and S. spinosa (Bennet and Thines 2018; Li et al. 2016). The life cycle of Halophytophthora/Salispina is characterized by a vegetative mycelial phase and a reproductive phase producing sympodial or irregular branching sporangiophores, papillate/non-papillate zoosporangia with smooth wall or spines, with or without an operculum, vesicle and plug (Nakagiri 2002). Halophytophthora/Salispina species generally are leaf degraders in tropical/subtropical mangrove environments but have also been isolated from leaf litter and organic debris in temperate locations (Man 2019; Nigrelli et al. 2013).
A fatty acid is a carboxylic acid with a long aliphatic chain, and can be categorized as saturated or unsaturated. The aliphatic chains in saturated fatty acids are linked by single bonds while those in unsaturated fatty acids are linked by one (monounsaturated fatty acid, MUFA) or more (polyunsaturated fatty acid, PUFA) double bonds. Docosahexaenoic acid (DHA, 22:6 (n-3)), eicosapentaenoic acid (EPA, 22:5 (n-3)), and arachidonic acid (ARA, 20:4 (n-6)) are examples of commonly known PUFAs that are beneficial to human health (Zárate et al. 2017). Many microorganisms are known to produce these essential PUFAs including fungi, Stramenopiles (thraustochytrids), bacteria, Cryptophyta, Haptophyceae and Alveolata (Kothri et al. 2020; Pang et al. 2016).
Pang et al. (2016) were the first to show that Halophytophthora and Salispina species (H. avicenniae, H. polymorphica, H. vesicula, Salispina spinosa) produced 14 different types of saturated (C10:0 capric acid, C12:0 lauric acid, C14:0 myristic acid, C15:0 pentadecanoic acid, C16:0 palmitic acid, C17-0 heptadecanoic acid, C18-0 stearic acid) and unsaturated (C16:1 palmitoleic acid, C16:2 hexadecadienoic acid, C18:1n-9c oleic acid, C18:1n-9t elaidic acid, C18:2n-6 linoleic acid, C20:4n-6 arachidonic acid, C20:5n-3 eicosapentaenoic acid) fatty acids in their mycelia, and different species showed dissimilar profiles in terms of type and quantity. For example, a high level of arachidonic acid (ARA), but no eicosapentaenoic acid (EPA), was produced by Halophytophthora spinosa (Pang et al. 2016), and this characteristic was used to justify the transfer of H. spinosa to the new genus Salispina (Li et al. 2016). EPA was also absent in isolates of S. spinosa and S. hoi from the Philippines (Caguimbal et al. 2019; Devanadera et al. 2019). Devanadera et al. (2019) further found C20:0 arachidic acid, C22:0 behenic acid, C23:0 tricosanoic acid, C24:0 lignoceric acid, C22:1 erucic acid, C18:3n-6 γ-linolenic acid, C20:3n-6 dihomo-gamma-linolenic acid and C18:3n-3 α-linolenic acid in mycelia of two unidentified Halophytophthora isolates and S. hoi.
Our research was proposed because: (1) unsaturated fatty acids, such as DHA and EPA, are beneficial to human health with fish oil as their main source; (2) there is a shortfall in the supply of DHA and EPA for human consumption based on the human population and the recommended daily intake of these essential fatty acids (Sprague et al. 2016); (3) an alternative source of DHA and EPA is required to meet demand for these fatty acids; (4) Halophytophthora and Salispina have been shown to produce a range of fatty acids including EPA (Pang et al. 2016). In this study, 24 saturated and unsaturated fatty acids in mycelia of 14 isolates of Halophytophthora species (H. avicenniae, H. batemanensis, H. exoprolifera, H. polymorphica) and Salispina spinosa cultured from mangrove leaves in Taiwan were screened. This study is the first to screen Halophytophthora and Salispina species for the fatty acids C18:1n-7 vaccenic acid, C20:1 eicosenoic acid, C24:1 nervonic acid, C20:2n-6 eicosadienoic acid, C22:4n-6 adrenic acid, C20:4n-3 eicosatetraenoic acid and C22:5n-3 docosapentaenoic acid. The fatty acid profiles of Halophytothphora batemanensis and H. exoprolifera are screened for the first time.
2 Materials and methods
2.1 Isolation
Fallen mangrove leaves were collected from mangroves at Hsin-fong (Hsinchu County), Chu-nan (Miaoli County), Pu-zi (Chiayi County), Fang-yuan (Zhanghua County) and Sih-cao (Tainan County), all located at the western side of the main Taiwan island. In the laboratory, the leaves were briefly washed with tap water and rinsed twice with sterile seawater (30 ‰). Washed leaf pieces (∼1 cm2 square) were submerged-inoculated in 15 ml sterile seawater (3%) supplemented with 0.5 g l−1 each of penicillin G sodium salt (Bioshop, Burlington, Canada) and streptomycin sulfate (Bioshop, Burlington, Canada) in Petri dishes and incubated at 25 °C in the dark for 2 days. Under a stereomicroscope, individual zoosporangia of different morphologies were picked with a flame-sterilised forceps and subcultured onto PYGS (peptone-yeast extract-glucose seawater) agar plates (4 g l−1 peptone (Oxoid, Basingstoke, UK), 4 g l−1 yeast extract (Oxoid, Basingstoke, UK), 4 g l−1 glucose (Bioshop, Burlinton, Canada), 14 g l−1 agar (Bioshop, Burlington, Canada), 30 g l−1 artificial sea salt) supplemented with antibiotics (0.5 g l−1 penicillin G sodium salt (Bioshop, Burlington, Canada), 0.5 g l−1 streptomycin sulfate (Bioshop, Burlington, Canada)). A total of 14 isolates were obtained.
2.2 Identification
For identification, sequence analysis of the 18S and internal transcribed spacer (ITS) regions of the rDNA were used. Mycelia were scraped from the surface of PYGS plates and ground into fine powder in liquid nitrogen using a mortar and a pestle. Genomic DNA was extracted using the DNeasy Plant DNA Extraction Kit (Qiagen, Hilden, Germany) according to the manufacturer’s instructions. The nuclear rRNA genes were amplified using primers NS1/NS4 or NS6 (18S) and ITS1 or ITS5/ITS4 (ITS) (White et al. 1990). PCR reactions were performed in a 25 µl volume containing 0.5 μl of the extracted DNA, 1 μl each of the two primers (10 μM), 12.5 μl Taq premix (BIOMAN, Taipei), 10 μl PCR water. The amplification cycle consisted of an initial denaturation step of 95 °C for 5 min followed by 35 cycles of (a) denaturation (95 °C for 30s), (b) annealing (55 °C for 30s) and (c) elongation (72 °C for 30 s) and a final 5-min elongation step at 72 °C. The PCR products were analyzed by agarose gel electrophoresis and sent to Genomics, Taipei, Taiwan for sequencing using the same primers. The sequences obtained were checked for ambiguity and assembled in MEGA7 (Kumar et al. 2016) and submitted to the National Center for Biotechnology Information (NCBI) for a nucleotide BLAST search.
2.3 Fatty acid analysis
Fourteen isolates were grown on PYGS agar plates for a week at 25 °C in the dark. Two agar disks (6 mm in diameter) were cut from the colony margin with a sterile Pasteur pipette and inoculated into Erlenmeyer flasks containing 20 ml medium with 4 g l−1 glucose (Bioshop, Burlinton, Canada), 4 g l−1 yeast extract (Oxoid, Basingstoke, UK), 4 g l−1 peptone (Oxoid, Basingstoke, UK) and 30 g l−1 artificial sea salt. Triplicate flasks were grown for each isolate and incubated at 25 °C in an orbital shaker at 100 rpm for one week. Mycelial biomass in the flasks was filtered, freeze-dried, weighed and ground.
Folch’s method was used for lipid extraction (Folch et al. 1957). Distilled water was added to 30 mg of freeze-dried mycelia, vortexed and allowed to stand for 30 min. Chloroform/methanol (2:1, v/v; 20 ml) was added for extraction at 4 °C overnight. Sodium chloride solution (0.9%, w/v; 4 ml) was added and the extracted lipids in chloroform were evaporated under a stream of nitrogen. The concentration of the lipids was adjusted to 2 mg ml−1 with chloroform. For fatty acid methyl ester (FAME) analysis, 0.1 ml of the total lipid-chloroform solution fraction was mixed with 0.1 ml of triheptadecanoin (0.16 mg ml−1; internal standard), evaporated under a stream of nitrogen, and reacted with 14% (w/v) boron trifluoride methanol complex for 20 min at 95 °C (Morrison and Smith 1964). Identification of FAME was performed by extraction with hexane, and separation and quantification using an Agilent 6890 gas chromatograph (GC) equipped with a flame-ionization detector and a fused-silica capillary column (Omegawax; 30 m × 0.32 mm, i.d., film thickness 0.25 μm, Supelco, Bellefonte, Pa., USA). The carrier gas was helium. The injector temperature was set at 205 °C, and the detector temperature at 240 °C. The temperature of the oven was initially 140 °C, and raised to 205 °C in increments of 6 °C min−1 and held for 20 min. The fatty acid peaks were identified by comparing their retention times to a mixture of FAME standards (mixture RL-461, Nu-Chek-Prep, Inc., Elysian, Minn., USA) and quantified according to their peak area using the Agilent ChemStation (Agilent Technologies, Palo Alto, Calif., U.S.A.) and the technique of internal standardization with triheptadecanoin serving as a standard (Sigma, St. Louis, Mo., USA).
The 24 fatty acids detected are listed in Table 1. The individual fatty acids produced by Halophytophthora spp. and Salispina spinosa were expressed as percentage of total fatty acid and yield (mg l−1 culture medium). Statistics was run in R (version 4.0.2). Data were compared using Kruskal-Wallis test, followed by Dunn’s multiple comparisons test. Multidimensional scaling (MDS) plot, based on Bray-Curtis distances, was performed on the fatty acid profiles of the isolates.
Fatty acids analysed in mycelia of species of Halophytophthora and Salispina in this study.
| Lipid number | Common name |
|---|---|
| C12:0 | Lauric acid |
| C14:0 | Myristic acid |
| C15:0 | Pentadecanoic acid |
| C16:0 | Palmitic acid |
| C18:0 | Stearic acid |
| C20:0 | Arachidic acid |
| C22:0 | Behenic acid |
| C24:0 | Lignoceric acid |
| C16:1 | Palmitoleic acid |
| C18:1n-9 | Oleic acid |
| C18:1n-7 | Vaccenic acid |
| C20:1 | Eicosenoic acid |
| C22:1 | Erucic acid |
| C24:1 | Nervonic acid |
| C18:2n-6 | Linoleic acid |
| C18:3n-6 | γ-Linolenic acid |
| C20:2n-6 | Eicosadienoic acid |
| C20:3n-6 | Dihomo-gamma-linolenic acid |
| C20:4n-6 | Arachidonic acid |
| C22:4n-6 | Adrenic acid |
| C18:3n-3 | α-Linolenic acid |
| C20:4n-3 | Eicosatetraenoic acid |
| C20:5n-3 | Eicosapentaenoic acid |
| C22:5n-3 | Docosapentaenoic acid |
3 Results
3.1 Identification of Halophytophthora/Salispina isolates
A total of 14 isolates were cultured from the fallen mangrove leaves. Based on the BLASTn results of 18S and ITS rDNA, 11 isolates were identified to belong to four Halophytophthora species (H. avicenniae, H. batemanensis, H. exoprolifera and H. polymorphica; Table 2). The BLASTn results of the ITS sequences suggest that IMB222, IMB224 and IMB226 belonged to the genus Phytopythium but the query coverage was very low (17–18%). These three isolates were identified as Salispina spinosa based on the partial 18S rDNA sequences (100% query coverage, 99% sequence similarity).
Results of nucleotide BLAST search in NCBI of the internal transcribed spacers (ITS) and 18S rDNA sequences of the 14 isolates of Halophytophthora [H. avicenniae (Gerr.-Corn. et J.A. Simpson] H.H. Ho et S.C. Jong, H. batemanensis (Gerr.-Corn. et J.A. Simpson) H.H. Ho et S.C. Jong, H. exoprolifera H.H. Ho, Nakagiri et S.Y. Newell, H. polymorphica (Gerr.-Corn. et J.A. Simpson) H.H. Ho et S.C. Jong) and Salispina [S. spinosa (Fell et Master) Marano, A.L. Jesus et Pires-Zottar.] examined in this study.
| Isolate no. | Locality | ITS rDNA | ||||||
|---|---|---|---|---|---|---|---|---|
| Sequence length (bp) | Max score | Query coverage (%) | Sequence similarity (%) | BLAST results (highest score) | Accession no. | Proposed taxon | ||
| IMB212 | Xin-fong, Hsinchu, Taiwan | 903 | 1611 | 96 | 100 | Halophytophthora avicenniae | KM205198 | Halophytophthora avicenniae |
| IMB213 | Xin-fong, Hsinchu, Taiwan | 871 | 1543 | 95 | 100 | Halophytophthora avicenniae | KM205202 | Halophytophthora avicenniae |
| IMB215 | Chu-nan, Miaoli, Taiwan | 882 | 1541 | 97 | 99 | Halophytophthora avicenniae | AY598668 | Halophytophthora avicenniae |
| IMB219 | Sih-cao, Tainan, Taiwan | 870 | 1543 | 95 | 100 | Halophytophthora avicenniae | KM205204 | Halophytophthora avicenniae |
| IMB225 | Pu-zi, Chiayi, Taiwan | 849 | 1537 | 98 | 99 | Halophytophthora avicenniae | KM205202 | Halophytophthora avicenniae |
| IMB216 | Fang-yuan, Zhanghua, Taiwan | 925 | 1631 | 97 | 99 | Halophytophthora batemanensis | GU258916 | Halophytophthora batemanensis |
| IMB217 | Sih-cao, Tainan, Taiwan | 932 | 1482 | 98 | 96 | Halophytophthora batemanensis | GU258910 | Halophytophthora batemanensis |
| IMB220 | Pu-zi, Chiayi, Taiwan | 908 | 1696 | 99 | 99 | Halophytophthora batemanensis | GU258916 | Halophytophthora batemanensis |
| IMB221 | Pu-zi, Chiayi, Taiwan | 929 | 1633 | 97 | 99 | Halophytophthora batemanensis | GU258916 | Halophytophthora batemanensis |
| IMB214 | Xin-fong, Hsinchu, Taiwan | 865 | 1502 | 95 | 99 | Halophytophthora exoprolifera | KT455402 | Halophytophthora exoprolifera |
| IMB227 | Sih-cao, Tainan, Taiwan | 891 | 1240 | 98 | 92 | Halophytophthora polymorphica | KT455403 | Halophytophthora polymorphica |
| IMB222 | Pu-zi, Chiayi, Taiwan | 879 | 271 | 18 | 96 | Phytopythium sp. | KM061666 | Not proposed |
| 271 | 18 | 96 | Uncultured stramenopile clone | HQ191349 | ||||
| IMB224 | Pu-zi, Chiayi, Taiwan | 888 | 271 | 17 | 96 | Phytopythium sp. | KM061666 | Not proposed |
| 271 | 18 | 96 | Uncultured stramenopile clone | HQ191349 | ||||
| IMB226 | Pu-zi, Chiayi, Taiwan | 888 | 271 | 17 | 96 | Phytopythium sp. | KM061666 | Not proposed |
| 271 | 18 | 96 | Uncultured stramenopile clone | HQ191349 | ||||
| IMB212 | Xin-fong, Hsinchu, Taiwan | 1050 | 1923 | 100% | 99% | Halophytophthora avicenniae | HQ161104 | Halophytophthora avicenniae |
| IMB213 | Xin-fong, Hsinchu, Taiwan | 1050 | 1940 | 100% | 100% | Halophytophthora avicenniae | HQ161104 | Halophytophthora avicenniae |
| IMB215 | Chu-nan, Miaoli, Taiwan | 1317 | 2433 | 100% | 100% | Halophytophthora avicenniae | HQ161104 | Halophytophthora avicenniae |
| IMB219 | Sih-cao, Tainan, Taiwan | 1318 | 2423 | 100% | 100% | Halophytophthora avicenniae | HQ161104 | Halophytophthora avicenniae |
| IMB225 | Pu-zi, Chiayi, Taiwan | 1050 | 1940 | 100% | 100% | Halophytophthora avicenniae | HQ161104 | Halophytophthora avicenniae |
| IMB216 | Fang-yuan, Zhanghua, Taiwan | 1318 | 2435 | 100% | 100% | Halophytophthora batemanensis | GU994179 | Halophytophthora batemanensis |
| IMB217 | Sih-cao, Tainan, Taiwan | 1317 | 2427 | 100% | 99% | Halophytophthora batemanensis | GU994179 | Halophytophthora batemanensis |
| IMB220 | Pu-zi, Chiayi, Taiwan | 1318 | 2427 | 99% | 99% | Halophytophthora batemanensis | GU994179 | Halophytophthora batemanensis |
| IMB221 | Pu-zi, Chiayi, Taiwan | 1327 | 2451 | 100% | 100% | Halophytophthora batemanensis | GU994179 | Halophytophthora batemanensis |
| IMB214 | Xin-fong, Hsinchu, Taiwan | 1053 | 1945 | 100% | 100% | Halophytophthora exoprolifera | GU994167 | Halophytophthora exoprolifera |
| IMB227 | Sih-cao, Tainan, Taiwan | 1049 | 1921 | 100% | 99% | Halophytophthora polymorphica | GU994176 | Halophytophthora polymorphica |
| IMB222 | Pu-zi, Chiayi, Taiwan | 1039 | 1919 | 100% | 99% | Salispina spinosa | HQ161101 | Salispina spinosa |
| IMB224 | Pu-zi, Chiayi, Taiwan | 1039 | 1908 | 100% | 99% | Salispina spinosa | HQ161101 | Salispina spinosa |
| IMB226 | Pu-zi, Chiayi, Taiwan | 1061 | 1943 | 100% | 99% | Salispina spinosa | HQ161101 | Salispina spinosa |
3.2 Fatty acid profile
Fatty acid profiles of the 14 isolates examined in this study are presented in Tables 3 and 4, showing the median percentage of TFA for the 24 different saturated and unsaturated fatty acids, and the yield (mg l−1), respectively. Mean percentage of TFA is given in Table 5. Species of Halophytophthora and Salispina produced a wide range of saturated and unsaturated fatty acids in varying quantities. Based on percentage of TFA (Table 3), five fatty acids were dominant (median >10%), including C16:0 palmitic acid (20–36%), C18:1n-9 oleic acid (7–20%), C18:2n-6 linoleic acid (13–25%), C20:4n-6 arachidonic acid (4–31%) and C20:5n-3 eicosapentaenoic acid (0.01–15%). Concerning yield (Table 4), these five fatty acids were also dominant: C16:0 palmitic acid (64–227 mg l−1), C18:1n-9 oleic acid (36–121 mg l−1), C18:2n-6 linoleic acid (43–155 mg l−1), C20:4n-6 arachidonic acid (18–188 mg l−1) and C20:5n-3 eicosapentaenoic acid (0.05–96 mg l−1). Eleven fatty acids were produced in low percentages of TFA (median <3%) and yield (median <12 mg l−1): 12:0 lauric acid, 15:0 pentadecanoic acid, 20:0 arachidic acid, 22:0 behenic acid, 24:0 lignoceric acid, C18:1n-7 vaccenic acid, C20:1 eicosenoic acid, C24:1 nervonic acid, C20:2n-6 eicosadienoic acid, C18:3n-3 α-linolenic acid and C20:4n-3 eicosatetraenoic acid.
Fatty acid profile (as percentage of total fatty acids) in mycelia of 14 isolates of Halophytophthora spp. (H. avicenniae: IMB212, IMB213, IMB215, IMB219, IMB225; H. batemanensis: IMB216, IMB217, IMB220, IMB221; H. exoprolifera: IMB214, H. polymorphica: IMB227) and Salispina spinosa (IMB222, IMB224, IMB226).
| Fatty acid | Isolate | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| IMB212 | IMB213 | IMB214 | IMB215 | IMB216 | IMB217 | IMB219 | IMB220 | IMB221 | IMB222 | IMB224 | IMB225 | IMB226 | IMB227 | |
| C12:0 | 0.06 a | 0.02 a | 0.03 a | 0.03 a | 0.03 a | 0.03 a | 0.01 a | 0.03 a | 0.06 a | 0.03 a | 0.02 a | 0.03 a | 0.02 a | 0.02 a |
| (0.06–0.07) | (0.02–0.16) | (0.03–0.03) | (0.03–0.04) | (0.03–0.05) | (0.03–0.03) | (0.01–0.02) | (0.03–0.04) | (0.05–0.08) | (0.02–0.05) | (0.02–0.02) | (0.03–0.04) | (0.02–0.02) | (0.02–0.02) | |
| C14:0 | 8.76 ab | 7.44 abc | 6.49 abc | 6.03 abc | 7.78 abc | 8.11 abc | 5.58 abc | 9.03 a | 10.22 a | 0.54 c | 0.55 bc | 6.39 abc | 0.51 c | 4.67 abc |
| (8.64–8.8) | (7.2–10.05) | (6.24–6.5) | (6.02–7.25) | (7.68–7.92) | (7.66–8.68) | (5.03–5.6) | (8.9–9.53) | (9.38–10.62) | (0.52–0.72) | (0.53–0.57) | (6.28–6.7) | (0.5–0.52) | (4.18–4.82) | |
| C15:0 | 0.57 abc | 0.38 abc | 0.30 abc | 1.11 abc | 0.25 abc | 0.13 abc | 0.73 ab | 0.15 abc | 0.16 abc | 0.08 c | 0.08 ac | 0.70 b | 0.08 c | 0.41 abc |
| (0.49–0.58) | (0.27–0.39) | (0.27–0.33) | (0.6–1.12) | (0.24–0.28) | (0.13–0.15) | (0.72–0.75) | (0.14–0.17) | (0.15–0.17) | (0.08–0.09) | (0.07–0.09) | (0.69–0.73) | (0.08–0.1) | (0.38–0.42) | |
| C16:0 | 25.16 ab | 26.00 ab | 35.72 a | 27.33 ab | 19.97 b | 24.40 ab | 22.03 ab | 22.20 ab | 22.67 ab | 27.61 a | 26.90 ab | 27.17 ab | 28.01 a | 21.35 ab |
| (25–25.54) | (23.18–26.49) | (34.17–36.72) | (23.79–27.37) | (19.55–20.08) | (22.94–24.47) | (21.25–22.45) | (22.05–22.41) | (21.73–23.01) | (27.3–28.65) | (26.89–26.95) | (25.3–27.33) | (27.67–28.52) | (21.32–22.33) | |
| C18:0 | 1.88 b | 2.58 ab | 1.70 ab | 3.04 ab | 2.94 ab | 3.50 ab | 1.67 b | 4.14 ab | 5.25 a | 2.30 ab | 2.57 ab | 2.18 ab | 2.64 ab | 3.90 ab |
| (1.8–2.01) | (2.48–3.33) | (1.45–2.84) | (2.69–3.66) | (2.76–3.29) | (3.22–3.61) | (1.53–1.74) | (3.96–4.17) | (4.73–5.3) | (2.24–3.12) | (2.46–2.64) | (2.15–2.36) | (2.38–2.66) | (3.35–4.54) | |
| C20:0 | 0.12 c | 0.25 abc | 0.13 bc | 0.22 abc | 0.34 abc | 0.29 abc | 0.19 abc | 0.46 ab | 0.58 a | 0.17 abc | 0.19 abc | 0.18 abc | 0.21 abc | 0.32 abc |
| (0.11–0.14) | (0.25–0.26) | (0.11–0.17) | (0.2–0.27) | (0.28–0.36) | (0.27–0.3) | (0.17–0.19) | (0.43–0.47) | (0.49–0.6) | (0.16–0.18) | (0.19–0.23) | (0.18–0.19) | (0.19–0.21) | (0.26–0.33) | |
| C22:0 | 0.07 c | 0.10 abc | 0.21 abc | 0.08 bc | 0.16 abc | 0.13 abc | 0.12 abc | 0.11 abc | 0.17 abc | 1.22 ab | 2.22 a | 0.09 bc | 1.80 ab | 0.42 abc |
| (0.07–0.08) | (0.1–0.14) | (0.21–0.32) | (0.07–0.13) | (0.16–0.17) | (0.13–0.15) | (0.12–0.13) | (0.11–0.14) | (0.17–0.25) | (1.17–1.64) | (2.21–2.28) | (0.08–0.11) | (1.69–1.84) | (0.35–0.42) | |
| C24:0 | 0.06 a | 0.03 a | 0.06 a | 0.08 a | 0.06 a | 0.11 a | 0.05 a | 0.05 a | 0.03 a | 0.26 a | 0.68 a | 0.05 a | 0.55 a | 0.04 a |
| (0.06–0.07) | (0.03–0.04) | (0.05–0.07) | (0.07–0.09) | (0.05–0.08) | (0.1–0.12) | (0.04–0.06) | (0.04–0.06) | (0.03–0.05) | (0.25–0.44) | (0.63–0.69) | (0.04–0.06) | (0.44–0.57) | (0.04–0.05) | |
| C16:1 | 1.88 bc | 2.99 ab | 6.25 a | 2.67 abc | 1.54 bc | 2.49 abc | 2.74 abc | 1.99 abc | 2.57 abc | 2.33 abc | 2.54 abc | 2.63 abc | 2.80 abc | 1.16 c |
| (1.81–1.97) | (2.8–3.09) | (6.13–7.41) | (2.65–2.71) | (1.51–1.7) | (2.34–2.52) | (2.73–2.75) | (1.89–2.21) | (2.26–2.66) | (2.3–2.33) | (2.39–2.9) | (2.55–2.7) | (2.51–2.87) | (1.15–1.3) | |
| C18:1n-9 | 12.03 abcd | 14.52 abcd | 15.90 ab | 14.03 abcd | 19.64 a | 12.71 abcd | 15.88 ab | 15.33 abcd | 13.48 abcd | 7.15 d | 8.22 bcd | 15.45 abc | 7.34 cd | 11.17 abcd |
| (11.7–12.17) | (13.08–14.71) | (15.66–17.7) | (13.71–14.3) | (19.29–20.41) | (12.35–14.26) | (15.87–17.05) | (14.99–15.47) | (12.49–15.01) | (7.03–7.21) | (8.08–8.37) | (15.42–16.8) | (7.1–7.86) | (10.67–11.65) | |
| C18:1n-7 | 0.23 abcd | 0.36 abcd | 0.59 abcd | 0.27 abcd | 0.61 ab | 0.48 abc | 0.27 abcd | 0.55 abc | 0.89 a | 0.04 d | 0.07 bcd | 0.24 abcd | 0.05 cd | 0.48 abcd |
| (0.23–0.23) | (0.35–0.4) | (0.53–0.61) | (0.27–0.44) | (0.59–0.68) | (0.45–0.78) | (0.27–0.29) | (0.55–0.58) | (0.75–0.91) | (0.04–0.05) | (0.06–0.08) | (0.23–0.26) | (0.05–0.06) | (0.4–0.48) | |
| C20:1 | 0.60 abcd | 0.31 abcd | 0.45 abcd | 0.37 abcd | 0.89 a | 0.88 ac | 0.31 abcd | 0.81 ac | 0.60 abc | 0.07 d | 0.10 bd | 0.26 bcd | 0.09 bd | 0.54 abcd |
| (0.54–0.62) | (0.27–0.33) | (0.39–0.48) | (0.35–0.38) | (0.88–0.91) | (0.8–1.14) | (0.3–0.34) | (0.8–0.82) | (0.58–0.61) | (0.07–0.08) | (0.1–0.11) | (0.25–0.28) | (0.09–0.09) | (0.51–0.55) | |
| C22:1 | 2.60 ab | 2.46 ab | 2.17 ab | 3.09 ab | 3.22 ab | 2.47 ab | 2.96 ab | 3.04 ab | 2.63 ab | 0.26 b | 0.33 b | 2.54 ab | 0.31 b | 3.56 a |
| (2.25–2.65) | (2.39–2.72) | (1.94–2.25) | (2.7–3.17) | (2.82–3.41) | (2.3–2.61) | (2.77–3.3) | (2.79–3.12) | (2.56–2.8) | (0.25–0.29) | (0.33–0.36) | (1.99–2.59) | (0.3–0.34) | (3.43–3.87) | |
| C24:1 | 0.29 ab | 0.35 ab | 0.58 a | 0.38 ab | 0.24 ab | 0.38 ab | 0.33 ab | 0.29 ab | 0.28 ab | 0.02 b | 0.03 b | 0.46 ab | 0.03 b | 1.28 a |
| (0.25–0.31) | (0.3–0.45) | (0.55–0.59) | (0.36–0.47) | (0.21–0.26) | (0.37–0.41) | (0.32–0.42) | (0.24–0.33) | (0.24–0.29) | (0.02–0.04) | (0.03–0.06) | (0.29–0.46) | (0.03–0.05) | (1.18–1.56) | |
| C18:2n-6 | 20.00 abc | 17.27 abc | 13.29 c | 17.28 abc | 15.00 c | 15.73 bc | 19.72 abc | 16.09 bc | 17.94 abc | 23.54 ab | 24.78 a | 16.43 bc | 22.84 ab | 20.18 abc |
| (19.89–20.04) | (17.21–19.44) | (12.68–14.06) | (16.9–19.82) | (14.33–15.03) | (15.46–17.24) | (19.3–19.74) | (15.94–16.3) | (17.09–18.95) | (22.68–23.57) | (24.47–25.02) | (16.04–16.47) | (22.39–22.89) | (20.01–21.18) | |
| C18:3n-6 | 2.04 abc | 1.60 abc | 1.10 bc | 1.59 abc | 2.55 ab | 3.31 ab | 1.22 bc | 3.79 a | 3.80 a | 1.05 bc | 1.46 abc | 1.82 abc | 1.07 bc | 0.77 c |
| (2.03–2.14) | (1.58–2.17) | (1.09–1.19) | (1.55–2.28) | (2.4–2.73) | (2.91–3.32) | (1.05–1.26) | (3.66–3.93) | (3.62–4.26) | (1.05–1.19) | (1.38–1.48) | (1.75–1.88) | (1–1.16) | (0.68–0.79) | |
| C20:2n-6 | 0.20 a | 0.17 a | 0.13 a | 0.19 a | 0.17 a | 0.27 a | 0.16 a | 0.19 a | 0.22 a | 0.32 a | 0.27 a | 0.14 a | 0.38 a | 0.22 a |
| (0.2–0.21) | (0.11–0.17) | (0.12–0.17) | (0.18–0.22) | (0.15–0.18) | (0.27–0.29) | (0.16–0.17) | (0.19–0.19) | (0.21–0.26) | (0.32–0.34) | (0.27–0.35) | (0.13–0.17) | (0.35–0.39) | (0.22–0.25) | |
| C20:3n-6 | 1.26 ab | 2.36 ab | 0.27 ab | 1.87 ab | 0.99 b | 3.70 ab | 1.73 ab | 2.63 ab | 3.46 a | 2.05 ab | 2.16 ab | 1.90 ab | 1.87 ab | 3.31 ab |
| (1.23–1.33) | (2.2–3.7) | (0.23–0.66) | (1.72–3.53) | (0.78–1.02) | (2.96–3.77) | (1.32–1.96) | (2.48–2.78) | (2.93–3.74) | (1.95–2.08) | (2.02–2.24) | (1.76–2.16) | (1.72–2.22) | (3.13–3.44) | |
| C20:4n-6 | 8.42 cde | 7.16 de | 4.06 e | 8.56 bcde | 9.80 abcde | 12.35 abcd | 10.79 abcde | 9.51 abcde | 6.39 de | 30.98 ab | 26.43 abc | 9.74 abcde | 29.50 a | 12.12 abcd |
| (8.13–8.52) | (6.33–7.8) | (3.7–4.58) | (7.31–8.98) | (9.72–9.82) | (11.75–13.17) | (10.71–11.82) | (9.12–9.78) | (6.34–6.4) | (29.24–31.17) | (26.25–26.97) | (9.62–9.89) | (29.23–29.89) | (11.43–13.58) | |
| C22:4n-6 | 0.02 ab | 0.02 ab | 0.03 ab | 0.03 ab | 0.02 ab | 0.06 a | 0.03 ab | 0.02 ab | 0.02 ab | 0.01 b | 0.01 ab | 0.03 ab | 0.02 ab | 0.05 ab |
| (0.02–0.02) | (0.02–0.02) | (0.03–0.04) | (0.02–0.04) | (0.02–0.03) | (0.06–0.07) | (0.03–0.04) | (0.02–0.03) | (0.02–0.03) | (0.01–0.02) | (0.01–0.02) | (0.03–0.03) | (0.02–0.02) | (0.04–0.05) | |
| C18:3n-3 | 0.01 a | 0.01 a | 0.01 a | 0.02 a | 0.01 a | 0.04 a | 0.02 a | 0.00 a | 0.03 a | 0.01 a | 0.02 a | 0.02 a | 0.01 a | 0.05 a |
| (0.01–0.02) | (0.01–0.05) | (0.01–0.14) | (0.02–0.04) | (0.01–0.01) | (0.04–0.41) | (0.02–0.03) | (0.00–0.01) | (0.02–0.04) | (0.01–0.02) | (0.02–0.03) | (0.02–0.02) | (0.01–0.02) | (0.04–0.05) | |
| C20:4n-3 | 0.04 ab | 0.07 a | 0.03 ab | 0.05 ab | 0.01 b | 0.03 ab | 0.05 ab | 0.05 ab | 0.10 a | 0.01 ab | 0.01 ab | 0.05 ab | 0.01 ab | 0.09 ab |
| (0.04–0.05) | (0.07–0.15) | (0.03–0.14) | (0.05–0.12) | (0.01–0.02) | (0.03–0.05) | (0.04–0.05) | (0.05–0.05) | (0.08–0.11) | (0.01–0.02) | (0.01–0.01) | (0.05–0.07) | (0.01–0.01) | (0.08–0.1) | |
| C20:5n-3 | 14.51 a | 11.12 abc | 8.05 abc | 11.47 abc | 14.43 a | 7.94 abc | 13.04 ab | 9.65 abc | 9.47 abc | 0.03 bc | 0.01 c | 11.48 abc | 0.03 bc | 12.53 abc |
| (13.79–14.54) | (10.67–11.85) | (7.73–8.44) | (10.62–11.63) | (13.96–14.5) | (7.25–8.39) | (12.81–13.13) | (9.46–9.69) | (8.41–10.1) | (0.03–0.05) | (0.01–0.02) | (11.4–12.44) | (0.03–0.03) | (11.75–13.01) | |
| C22:5n-3 | 0.04 abc | 0.04 abc | 0.04 abc | 0.06 ab | 0.05 abc | 0.09 a | 0.03 abc | 0.03 abc | 0.03 abc | 0.02 c | 0.01 c | 0.04 abc | 0.02 bc | 0.04 abc |
| (0.04–0.05) | (0.04–0.05) | (0.04–0.05) | (0.06–0.07) | (0.04–0.05) | (0.08–0.09) | (0.03–0.04) | (0.03–0.04) | (0.03–0.04) | (0.02–0.02) | (0.01–0.01) | (0.04–0.05) | (0.02–0.02) | (0.03–0.05) | |
-
Data are expressed as median (interquartile range). Values in the same row with the same superscript letter are not significantly different at p=0.05.
Fatty acid yield (mg l−1) in mycelia of 14 isolates of Halophytophthora spp. (H. avicenniae: IMB212, IMB213, IMB215, IMB219, IMB225; H. batemanensis: IMB216, IMB217, IMB220, IMB221; H. exoprolifera: IMB214, H. polymorphica: IMB227) and Salispina spinosa (IMB222, IMB224, IMB226).
| Fatty acid | Isolate | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| IMB212 | IMB213 | IMB214 | IMB215 | IMB216 | IMB217 | IMB219 | IMB220 | IMB221 | IMB222 | IMB224 | IMB225 | IMB226 | IMB227 | |
| C12:0 | 0.29 a | 0.05 a | 0.19 a | 0.11 a | 0.11 a | 0.15 a | 0.05 a | 0.17 a | 0.25 a | 0.15 a | 0.11 a | 0.23 a | 0.13 a | 0.15 a |
| (0.29–0.32) | (0.05–0.39) | (0.19–0.19) | (0.09–0.14) | (0.09–0.18) | (0.13–0.15) | (0.05–0.08) | (0.14–0.20) | (0.21–0.33) | (0.10–0.25) | (0.08–0.11) | (0.20–0.27) | (0.13–0.13) | (0.15–0.15) | |
| C14:0 | 42.49 ab | 18.34 ab | 41.26 ab | 21.83 ab | 27.82 ab | 40.81 ab | 28.77 ab | 51.23 a | 42.24 ab | 2.73 b | 2.94 b | 50.02 a | 3.25 b | 35.81 ab |
| (41.88–42.66) | (17.73–24.77) | (39.67–41.32) | (21.78–26.25) | (27.46–28.3) | (38.52–43.67) | (25.91–28.85) | (50.5–54.07) | (38.75–43.87) | (2.63–3.64) | (2.81–3.05) | (49.16–52.45) | (3.16–3.28) | (32.01–36.92) | |
| C15:0 | 2.76 ab | 0.94 ab | 1.91 ab | 4.02 ab | 0.89 ab | 0.65 ab | 3.76 ab | 0.85 ab | 0.66 ab | 0.40 b | 0.43 b | 5.48 a | 0.51 ab | 3.14 ab |
| (2.38–2.81) | (0.67–0.95) | (1.72–2.07) | (2.17–4.05) | (0.86–0.98) | (0.63–0.73) | (3.69–3.84) | (0.79–0.96) | (0.60–0.68) | (0.40–0.43) | (0.35–0.45) | (5.40–5.68) | (0.51–0.61) | (2.91–3.22) | |
| C16:0 | 122.03 abc | 64.08 c | 227.08 a | 98.95 bc | 71.41 c | 122.77 abc | 113.59 abc | 125.95 abc | 93.69 bc | 139.63 abc | 143.74 abc | 212.69 a | 178.55 ab | 163.71 ab |
| (121.25–123.84) | (57.13–65.29) | (217.19–233.4) | (86.11–99.09) | (69.89–71.81) | (115.42–123.1) | (109.56–115.75) | (125.07–127.15) | (89.81–95.08) | (138.06–144.89) | (143.66–144.01) | (198.01–213.94) | (176.38–181.77) | (163.44–171.23) | |
| C18:0 | 9.12 bd | 6.36 d | 10.81 abcd | 11.01 abcd | 10.51 abcd | 17.61 abcd | 8.61 cd | 23.49 ab | 21.70 abcd | 11.63 abcd | 13.73 abcd | 17.07 abcd | 16.83 abcd | 29.91 ac |
| (8.71–9.75) | (6.11–8.2) | (9.19–18.02) | (9.72–13.25) | (9.85–11.77) | (16.18–18.16) | (7.89–8.97) | (22.44–23.66) | (19.53–21.88) | (11.3–15.75) | (13.15–14.11) | (16.83–18.43) | (15.17–16.96) | (25.65–34.77) | |
| C20:0 | 0.58 b | 0.62 b | 0.83 ab | 0.80 ab | 1.22 ab | 1.46 ab | 0.98 ab | 2.61 a | 2.40 a | 0.86 ab | 1.02 ab | 1.41 ab | 1.34 ab | 2.45 a |
| (0.51–0.65) | (0.6–0.64) | (0.67–1.05) | (0.71–0.96) | (0.98–1.27) | (1.33–1.48) | (0.85–0.98) | (2.41–2.67) | (2.03–2.46) | (0.81–0.91) | (0.99–1.20) | (1.41–1.45) | (1.21–1.34) | (1.96–2.49) | |
| C22:0 | 0.34 c | 0.25 c | 1.34 abc | 0.29 bc | 0.57 abc | 0.65 abc | 0.62 abc | 0.62 abc | 0.70 abc | 6.17 ab | 11.86 a | 0.70 abc | 11.47 a | 3.22 abc |
| (0.32–0.36) | (0.23–0.33) | (1.30–2.00) | (0.25–0.47) | (0.57–0.61) | (0.63–0.75) | (0.59–0.67) | (0.62–0.79) | (0.68–1.03) | (5.92–8.27) | (11.78–12.16) | (0.59–0.86) | (10.77–11.70) | (2.65–3.22) | |
| C24:0 | 0.29 abc | 0.07 c | 0.38 abc | 0.29 abc | 0.21 abc | 0.55 ab | 0.26 abc | 0.28 abc | 0.12 bc | 1.31 ab | 3.63 ab | 0.39 abc | 3.51 a | 0.31 abc |
| (0.29–0.32) | (0.06–0.09) | (0.32–0.41) | (0.24–0.33) | (0.18–0.27) | (0.50–0.58) | (0.18–0.28) | (0.20–0.31) | (0.12–0.19) | (1.26–2.23) | (3.34–3.66) | (0.31–0.43) | (2.80–3.63) | (0.27–0.35) | |
| C16:1 | 9.12 bcd | 7.37 cd | 39.73 a | 9.67 bcd | 5.51 d | 12.53 abcd | 14.13 abc | 11.29 abcd | 10.62 abcd | 11.78 abcd | 13.57 abcd | 20.59 bc | 17.85 bc | 8.89 bcd |
| (8.78–9.53) | (6.90–7.60) | (38.97–47.11) | (9.58–9.79) | (5.38–6.06) | (11.75–12.65) | (14.08–14.18) | (10.69–12.54) | (9.34–10.97) | (11.63–11.78) | (12.77–15.50) | (19.92–21.14) | (15.97–18.29) | (8.82–9.93) | |
| C18:1n-9 | 58.35 abc | 35.79 c | 101.08 a | 50.79 abc | 70.23 abc | 63.95 abc | 81.88 ab | 86.98 ab | 55.71 abc | 36.16 c | 43.92 bc | 120.94 a | 46.79 bc | 85.65 ab |
| (56.75–59.02) | (32.24–36.24) | (99.52–112.52) | (49.64–51.77) | (68.96–72.97) | (62.12–71.73) | (81.83–87.91) | (85.02–87.74) | (51.6–62.03) | (35.53–36.46) | (43.15–44.73) | (120.71–131.51) | (45.26–50.07) | (81.78–89.29) | |
| C18:1n-7 | 1.12 abc | 0.89 abc | 3.75 a | 0.98 abc | 2.18 abc | 2.42 ab | 1.39 abc | 3.12 a | 3.68 a | 0.20 c | 0.37 bc | 1.88 abc | 0.32 bc | 3.68 a |
| (1.09–1.12) | (0.86–0.97) | (3.34–3.88) | (0.96–1.57) | (2.09–2.43) | (2.26–3.92) | (1.37–1.50) | (3.12–3.26) | (3.10–3.76) | (0.20–0.25) | (0.32–0.43) | (1.80–2.00) | (0.32–0.35) | (3.07–3.68) | |
| C20:1 | 2.91 abcd | 0.76 bcd | 2.86 abcd | 1.34 abcd | 3.18 abc | 4.43 a | 1.60 abcd | 4.60 a | 2.48 abcd | 0.35 d | 0.53 cd | 2.04 abcd | 0.57 cd | 4.14 ab |
| (2.62–3.01) | (0.67–0.80) | (2.48–3.02) | (1.27–1.38) | (3.13–3.25) | (4.00–5.71) | (1.55–1.75) | (4.54–4.65) | (2.40–2.52) | (0.33–0.38) | (0.51–0.59) | (1.96–2.19) | (0.54–0.57) | (3.87–4.18) | |
| C22:1 | 12.61 abcd | 6.06 bcd | 13.80 abcd | 11.19 abcd | 11.51 abcd | 12.43 abcd | 15.26 abc | 17.25 ab | 10.87 abcd | 1.31 b | 1.76 cd | 19.88 abc | 1.98 bcd | 27.30 a |
| (10.91–12.83) | (5.89–6.70) | (12.3–14.3) | (9.78–11.48) | (10.08–12.18) | (11.57–13.13) | (14.28–17.01) | (15.83–17.7) | (10.56–11.57) | (1.26–1.44) | (1.74–1.92) | (15.58–20.24) | (1.91–2.17) | (26.26–29.64) | |
| C24:1 | 1.41 ab | 0.86 ab | 3.69 a | 1.38 ab | 0.86 ab | 1.91 ab | 1.70 ab | 1.65 ab | 1.16 ab | 0.10 b | 0.16 b | 3.60 ab | 0.19 b | 9.82 a |
| (1.21–1.50) | (0.74–1.11) | (3.50–3.75) | (1.30–1.68) | (0.75–0.93) | (1.86–2.06) | (1.65–2.14) | (1.36–1.84) | (0.99–1.20) | (0.10–0.20) | (0.16–0.32) | (2.23–3.60) | (0.19–0.29) | (9.05–11.92) | |
| C18:2n-6 | 97.00 abcd | 42.57 d | 84.49 abcd | 62.56 cd | 53.64 d | 79.15 abcd | 101.68 abcd | 91.29 abcd | 74.14 bcd | 119.05 abcd | 132.41 abc | 128.61 abc | 145.59 ab | 154.74 a |
| (96.44–97.19) | (42.41–47.91) | (80.61–89.38) | (61.18–71.76) | (51.23–53.73) | (77.76–86.72) | (99.51–101.78) | (90.41–92.45) | (70.63–78.32) | (114.67–119.17) | (130.73–133.67) | (125.56–128.93) | (142.69–145.88) | (153.44–162.37) | |
| C18:3n-6 | 9.89 abc | 3.94 a | 6.99 abc | 5.76 abc | 9.12 abc | 16.65 abc | 6.29 ab | 21.50 c | 15.70 bc | 5.31 ab | 7.80 abc | 14.25 abc | 6.82 abc | 5.90 ab |
| (9.85–10.38) | (3.89–5.35) | (6.93–7.57) | (5.59–8.24) | (8.58–9.74) | (14.64–16.70) | (5.39–6.47) | (20.77–22.27) | (14.96–17.59) | (5.31–6.02) | (7.37–7.91) | (13.66–14.72) | (6.34–7.36) | (5.18–6.02) | |
| C20:2n-6 | 0.97 abcd | 0.42 d | 0.83 abcd | 0.69 bcd | 0.61 cd | 1.36 abcd | 0.82 abcd | 1.08 abcd | 0.91 abcd | 1.62 ab | 1.44 abc | 1.10 abcd | 2.42 c | 1.69 ab |
| (0.97–0.99) | (0.27–0.42) | (0.76–1.08) | (0.63–0.78) | (0.54–0.63) | (1.33–1.46) | (0.80–0.88) | (1.05–1.08) | (0.85–1.05) | (1.59–1.69) | (1.42–1.84) | (1.02–1.29) | (2.23–2.45) | (1.65–1.92) | |
| C20:3n-6 | 6.11 ab | 5.82 ab | 1.72 b | 6.77 ab | 3.54 b | 18.62 ab | 8.92 ab | 14.92 ab | 14.30 ab | 10.37 ab | 11.54 ab | 14.87 ab | 11.92 ab | 25.38 a |
| (5.97–6.45) | (5.42–9.11) | (1.46–4.20) | (6.21–12.76) | (2.77–3.65) | (14.87–18.94) | (6.81–10.08) | (14.04–15.74) | (12.11–15.44) | (9.84–10.49) | (10.79–11.97) | (13.74–16.87) | (10.96–14.15) | (23.96–26.38) | |
| C20:4n-6 | 40.84 abcd | 17.65 d | 25.81 cd | 30.99 cd | 35.04 bcd | 62.14 abcd | 55.63 abcd | 53.96 abcd | 26.41 cd | 156.67 ab | 141.23 ab | 76.24 abc | 188.04 a | 92.94 abc |
| (39.41–41.32) | (15.59–19.23) | (23.52–29.12) | (26.47–32.49) | (34.76–35.10) | (59.10–66.24) | (55.22–60.92) | (51.71–55.49) | (26.2–26.45) | (147.87–157.63) | (140.27–144.09) | (75.27–77.42) | (186.29–190.50) | (87.65–104.09) | |
| C22:4n-6 | 0.10 ab | 0.05 b | 0.19 ab | 0.11 ab | 0.07 ab | 0.30 a | 0.15 ab | 0.11 ab | 0.08 ab | 0.05 ab | 0.05 ab | 0.23 ab | 0.13 ab | 0.38 a |
| (0.10–0.10) | (0.05–0.05) | (0.16–0.25) | (0.07–0.13) | (0.07–0.09) | (0.28–0.35) | (0.15–0.21) | (0.11–0.14) | (0.08–0.12) | (0.05–0.08) | (0.05–0.08) | (0.23–0.23) | (0.10–0.13) | (0.27–0.38) | |
| C18:3n-3 | 0.05 a | 0.02 a | 0.06 a | 0.07 a | 0.04 a | 0.20 a | 0.10 a | 0.00 a | 0.12 a | 0.05 a | 0.11 a | 0.16 a | 0.06 a | 0.38 a |
| (0.02–0.07) | (0.01–0.11) | (0.06–0.86) | (0.05–0.14) | (0.04–0.04) | (0.18–2.04) | (0.08–0.13) | (0.00–0.03) | (0.08–0.17) | (0.05–0.10) | (0.11–0.16) | (0.12–0.16) | (0.06–0.10) | (0.27–0.38) | |
| C20:4n-3 | 0.19 ab | 0.17 ab | 0.19 ab | 0.18 ab | 0.04 ab | 0.15 ab | 0.26 ab | 0.28 ab | 0.41 ab | 0.05 b | 0.05 ab | 0.39 ab | 0.06 ab | 0.69 a |
| (0.19–0.22) | (0.17–0.36) | (0.16–0.89) | (0.16–0.42) | (0.04–0.05) | (0.15–0.25) | (0.21–0.26) | (0.26–0.28) | (0.33–0.43) | (0.05–0.08) | (0.05–0.05) | (0.35–0.55) | (0.06–0.06) | (0.58–0.73) | |
| C20:5n-3 | 70.37 ab | 27.41 bcd | 51.18 abcd | 41.53 abcd | 51.60 abcd | 39.95 abcd | 67.23 abc | 54.75 abcd | 39.14 abcd | 0.15 cd | 0.05 d | 89.87 a | 0.19 cd | 96.08 a |
| (66.86–70.49) | (26.29–29.21) | (49.14–53.65) | (38.43–42.09) | (49.90–51.85) | (36.48–42.19) | (66.05–67.70) | (53.64–54.98) | (34.76–41.74) | (0.15–0.25) | (0.05–0.08) | (89.20–97.38) | (0.16–0.19) | (90.06–99.76) | |
| C22:5n-3 | 0.19 abc | 0.10 bc | 0.25 ab | 0.22 abc | 0.18 abc | 0.45 a | 0.15 abc | 0.17 abc | 0.12 abc | 0.10 bc | 0.05 c | 0.31 a | 0.13 abc | 0.31 abc |
| (0.17–0.24) | (0.09–0.11) | (0.25–0.32) | (0.20–0.24) | (0.14–0.18) | (0.38–0.45) | (0.15–0.18) | (0.17–0.20) | (0.10–0.17) | (0.08–0.10) | (0.05–0.05) | (0.31–0.35) | (0.13–0.13) | (0.23–0.35) | |
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Data are expressed as median (interquartile range). Values in the same row with the same superscript letter are not significantly different at p=0.05.
Fatty acid profiles of species of Halophytophthora and Salispina grown in different media based on mean percentage of total fatty acid.
| Species | Halophytophthora avicenniae IMB212 | Halophytophthora avicenniae IMB213 | Halophytophthora avicenniae IMB215 | Halophytophthora avicenniae IMB219 | Halophytophthora avicenniae IMB225 | Halophytophthora batemanensis IMB216 | Halophytophthora batemanensis IMB217 | Halophytophthora batemanensis IMB220 | Halophytophthora batemanensis IMB221 | Halophytophthora exoprolifera IMB214 | Halophytophthora polymorphica IMB227 | Salispina spinosa IMB222 | Salispina spinosa IMB224 | Salispina spinosa IMB226 | Halophytophthora avicenniae IMB144 | Halophytophthora avicenniae IMB145 | Halophytophthora avicenniae IMB157 | Halophytophthora avicenniae IMB158 | Halophytophthora avicenniae IMB159 | Halophytophthora avicenniae IMB160 | Halophytophthora avicenniae IMB164 | Halophytophthora polymorphica IMB146 | Halophytophthora vesicula IMB147 | Salispina spinosa IMB162 | Halophytophthora vesicula AK1YB2 | Halophytophthora vesicula PQ1YB3 | Salispina spinosa ST1YB3 | Halophytophthora vesicula AK1YB2 | Halophytophthora vesicula PQ1YB3 | Salispina spinosa ST1YB3 | Halophytophthora sp. T12GP1 | Halophytophthora sp. T12YBP2 | Salispina hoi | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Medium | 4 g l−1 glucose, 4 g l−1 yeast extract, 4 g l−1 peptone, 3% artificial sea salt | 4 g l−1 glucose, 4 g l−1 yeast extract, 4 g l−1 peptone, 2.5 % seawater | 10 g l−1 glucose, 4 g l−1 yeast extract, 4 g l−1 peptone, 50% sterile seawater or 25 g l−1 marine salt | 20% (v/v) V8 juice Campbell, 3 g l−1 calcium carbonate, 50% sterile seawater or 25 g l−1 marine salt | 5% (v/v) clarified vegetable juice, 4 g l−1 glucose, 4 g l−1 yeast extract, 4 g l−1 peptone, 10 g l−1 marine salt | |||||||||||||||||||||||||||||
| Fatty acid profile (% in total fatty acid) | C10:0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 0.42 | 0.38 | 0.00 | 0.05 | 0.00 | 0.00 | 0.05 | 0.13 | 0.06 | 0.00 | NA | NA | NA | NA | NA | NA | – | – | 0.29 |
| C12:0 | 0.06 | 0.11 | 0.03 | 0.01 | 0.03 | 0.04 | 0.03 | 0.03 | 0.07 | 0.03 | 0.02 | 0.04 | 0.02 | 0.02 | 1.08 | 1.00 | 0.17 | 0.29 | 0.19 | 0.20 | 0.32 | 0.70 | 1.09 | 0.06 | NA | NA | NA | NA | NA | NA | 2.13 | 0.81 | 0.69 | |
| C14:0 | 8.70 | 9.02 | 6.83 | 5.22 | 6.52 | 7.80 | 8.19 | 9.28 | 9.92 | 6.33 | 4.44 | 0.65 | 0.55 | 0.50 | 13.89 | 13.75 | 12.27 | 15.20 | 12.14 | 12.88 | 16.89 | 19.51 | 9.34 | 1.30 | 5.89 | 3.53 | 2.66 | 0.73 | 0.39 | 0.80 | 8.64 | 5.90 | 1.32 | |
| C15:0 | 0.52 | 0.31 | 0.78 | 0.73 | 0.71 | 0.26 | 0.14 | 0.16 | 0.15 | 0.30 | 0.40 | 0.08 | 0.07 | 0.09 | 0.67 | 0.74 | 0.40 | 0.34 | 0.89 | 0.76 | 1.20 | 3.45 | 0.79 | 0.11 | NA | NA | NA | NA | NA | NA | 0.79 | 0.59 | – | |
| C16:0 | 25.30 | 24.45 | 24.99 | 21.79 | 26.03 | 19.76 | 23.47 | 22.24 | 22.27 | 35.35 | 21.98 | 28.10 | 26.92 | 28.12 | 21.34 | 21.97 | 29.28 | 26.63 | 26.34 | 26.26 | 25.72 | 13.40 | 29.07 | 30.14 | 25.20 | 9.47 | 28.31 | 9.45 | 14.40 | 13.41 | 32.62 | 30.00 | 38.56 | |
| C17:0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 0.54 | 0.59 | 0.52 | 0.45 | 0.85 | 0.77 | 0.90 | 3.50 | 1.14 | 1.38 | NA | NA | NA | NA | NA | NA | 0.82 | 0.56 | – | |
| C18:0 | 1.91 | 3.01 | 3.22 | 1.62 | 2.28 | 3.05 | 3.38 | 4.04 | 4.93 | 2.29 | 3.95 | 2.80 | 2.54 | 2.48 | 1.06 | 1.10 | 1.47 | 1.73 | 1.81 | 1.41 | 0.89 | 1.72 | 4.84 | 1.36 | 2.54 | 0.68 | 7.54 | 1.91 | 1.89 | 2.58 | 6.82 | 8.08 | 4.93 | |
| C20:0 | 0.12 | 0.25 | 0.23 | 0.17 | 0.18 | 0.31 | 0.28 | 0.44 | 0.53 | 0.14 | 0.28 | 0.17 | 0.21 | 0.20 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 1.46 | 1.87 | – | |
| C22:0 | 0.07 | 0.12 | 0.11 | 0.12 | 0.09 | 0.17 | 0.14 | 0.13 | 0.22 | 0.28 | 0.37 | 1.46 | 2.25 | 1.75 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 1.77 | 2.20 | 0.57 | |
| C23:0 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 3.08 | 4.61 | 0.41 | |
| C24:0 | 0.06 | 0.03 | 0.08 | 0.04 | 0.05 | 0.06 | 0.11 | 0.04 | 0.04 | 0.06 | 0.04 | 0.37 | 0.65 | 0.49 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | – | 0.89 | 0.25 | |
| C16:1 | 1.89 | 2.93 | 2.68 | 2.74 | 2.62 | 1.62 | 2.40 | 2.07 | 2.42 | 6.94 | 1.24 | 2.31 | 2.68 | 2.65 | 2.43 | 2.39 | 2.79 | 3.14 | 3.08 | 3.24 | 3.21 | 7.63 | 2.25 | 3.25 | 3.56 | 3.87 | 3.06 | 1.30 | 1.48 | 0.92 | 2.71 | 2.50 | 0.90 | |
| C16:2 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 0.21 | 0.23 | 0.21 | 0.17 | 0.36 | 0.37 | 0.41 | 0.90 | 0.53 | 0.04 | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| C18:1n-9c | 11.90 | 13.68 | 14.00 | 16.65 | 16.33 | 19.91 | 13.50 | 15.19 | 13.84 | 16.94 | 11.15 | 7.11 | 8.22 | 7.52 | 9.75 | 10.11 | 13.46 | 14.68 | 12.55 | 12.74 | 10.40 | 6.61 | 14.18 | 4.11 | 14.85 | 8.45 | 14.89 | 8.03 | 8.22 | 10.27 | 17.43 | 15.56 | 32.12 | |
| C18:1n-9t | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 0.32 | 0.34 | 0.24 | 0.27 | 0.23 | 0.27 | 0.22 | 1.21 | 0.56 | 0.02 | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| C18:1n-7 | 0.23 | 0.38 | 0.38 | 0.28 | 0.24 | 0.64 | 0.66 | 0.57 | 0.81 | 0.56 | 0.43 | 0.05 | 0.07 | 0.05 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| C20:1 | 0.57 | 0.29 | 0.36 | 0.32 | 0.27 | 0.89 | 0.99 | 0.81 | 0.59 | 0.43 | 0.52 | 0.07 | 0.10 | 0.09 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| C22:1 | 2.40 | 2.59 | 2.88 | 3.06 | 2.20 | 3.08 | 2.45 | 2.93 | 2.69 | 2.07 | 3.67 | 0.27 | 0.35 | 0.32 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 3.23 | 2.09 | – | |
| C24:1 | 0.28 | 0.38 | 0.42 | 0.38 | 0.34 | 0.23 | 0.39 | 0.28 | 0.26 | 0.57 | 1.40 | 0.03 | 0.05 | 0.04 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| C18:2n-6 | 19.95 | 18.67 | 18.72 | 19.45 | 16.20 | 14.57 | 16.55 | 16.12 | 18.05 | 13.40 | 20.73 | 22.98 | 24.73 | 22.57 | 18.87 | 19.21 | 16.63 | 16.45 | 16.82 | 17.08 | 17.82 | 16.90 | 13.21 | 33.19 | 24.65 | 15.46 | 30.70 | 14.44 | 12.58 | 21.60 | 13.86 | 16.12 | 18.59 | |
| C18:3n-6 | 2.10 | 1.97 | 2.02 | 1.13 | 1.81 | 2.57 | 3.05 | 3.79 | 3.98 | 1.15 | 0.72 | 1.14 | 1.42 | 1.08 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 1.13 | 1.98 | – | |
| C20:2n-6 | 0.20 | 0.13 | 0.20 | 0.16 | 0.15 | 0.16 | 0.28 | 0.19 | 0.23 | 0.15 | 0.24 | 0.33 | 0.32 | 0.36 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| C20:3n-6 | 1.29 | 3.14 | 2.87 | 1.61 | 1.97 | 0.87 | 3.25 | 2.62 | 3.29 | 0.50 | 3.27 | 2.00 | 2.12 | 2.00 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | 2.11 | 3.25 | – | |
| C20:4n-6 | 8.29 | 7.03 | 8.00 | 11.42 | 9.76 | 9.76 | 12.49 | 9.43 | 6.36 | 4.17 | 12.63 | 29.95 | 26.67 | 29.57 | 11.00 | 10.69 | 7.53 | 7.16 | 10.84 | 8.42 | 7.47 | 11.10 | 14.72 | 25.02 | 20.79 | 16.06 | 19.95 | 2.96 | 1.82 | 4.13 | NA | NA | NA | |
| C22:4n-6 | 0.02 | 0.02 | 0.03 | 0.04 | 0.03 | 0.02 | 0.06 | 0.02 | 0.03 | 0.03 | 0.04 | 0.01 | 0.01 | 0.02 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| C18:3n-3 | 0.01 | 0.03 | 0.03 | 0.02 | 0.02 | 0.01 | 0.28 | 0.00 | 0.03 | 0.09 | 0.04 | 0.02 | 0.03 | 0.01 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | – | 0.93 | 1.38 | |
| C20:4n-3 | 0.04 | 0.12 | 0.09 | 0.04 | 0.06 | 0.01 | 0.04 | 0.05 | 0.09 | 0.10 | 0.08 | 0.01 | 0.01 | 0.01 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| C20:5n-3 | 14.04 | 11.30 | 11.00 | 12.95 | 12.06 | 14.16 | 7.78 | 9.55 | 9.18 | 8.10 | 12.33 | 0.04 | 0.01 | 0.03 | 18.42 | 17.50 | 15.05 | 13.43 | 13.91 | 15.61 | 14.49 | 13.24 | 8.21 | 0.01 | – | – | – | – | – | – | 1.40 | 2.07 | – | |
| C22:5n-3 | 0.04 | 0.04 | 0.06 | 0.03 | 0.04 | 0.04 | 0.08 | 0.03 | 0.03 | 0.05 | 0.04 | 0.02 | 0.01 | 0.02 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
| Reference | This study | Pang et al. (2016) | Caguimbal et al. (2019) | Devanadera et al. (2019) | ||||||||||||||||||||||||||||||
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NA, not available.
Concerning the essential arachidonic (ARA) and eicosapentaenoic (EPA) acids, S. spinosa isolates produced the highest amount of ARA (26–31% of TFA, 141–188 mg l−1 yield) of all the isolates, but produced only low levels of EPA (0.01–0.03% of TFA, 0.05–1.19 mg l−1 yield; Figure 1). Halophytophthora spp. generally produced slightly higher quantities of EPA (8–15% of TFA, 27–96 mg l−1) than ARA (4–12% of TFA, 18–93 mg l−1). For EPA, H. avicenniae IMB212 produced the highest percentage of TFA (15%) while H. polymorphica IMB227 produced the highest yield (96 mg l−1) of EPA.
Production of arachidonic (ARA) and eicosapentaenoic (EPA) acids in mycelia of the 14 isolates of Halophytophthora spp. (H. avicenniae: IMB212, IMB213, IMB215, IMB219, IMB225; H. batemanensis: IMB216, IMB217, IMB220, IMB221; H. exoprolifera IMB214; H. polymorphica IMB227) and Salispina spinosa (IMB222, IMB224, IMB226): (a) percentage of total fatty acids based on median and interquartile range and (b) yield (mg l−1).
The cluster analysis based on the fatty acid profile is shown in Figure 2. The fatty acid profiles of H. avicenniae, H. batemanensis and H. polymorphica were similar, while H. exoprolifera and S. spinosa formed different clusters based on percentage of TFA (Figure 2a). However, the clusters were more dispersed based on fatty acid yield (Figure 2b); H. exoprolifera, S. spinosa, H. avicenniae (IMB213, IMB225) and H. polymorphica formed a separate cluster from the main cluster consisting of H. avicenniae (IMB212, IMB215, IMB219) and H. batemanensis (IMB216, IMB217, IMB220, IMB221).
Multidimensional scaling (MDS) plot using Bray-Curtis distances based on fatty acid profile in mycelia of the 14 isolates of Halophytophthora spp. (H. avicenniae: IMB212, IMB213, IMB215, IMB219, IMB225; H. batemanensis: IMB216, IMB217, IMB220, IMB221; H. exoprolifera IMB214; H. polymorphica IMB227) and Salispina spinosa (IMB222, IMB224, IMB226): (a) percentage of total fatty acids and (b) yield (mg l−1).
4 Discussion
DHA and EPA have been suggested to benefit fetal development, cardiovascular function, and Alzheimer’s disease in humans (Swanson et al. 2012). The marine Labyrinthulomycetes are prolific producers of DHA, but poor producers of EPA (Ou et al. 2016). Oomycota and Mucoromycota, on the other hand, produce EPA, in particular, species of Mortierella with high yields of EPA (Cheng et al. 1999; Jang et al. 2005). Halophytophthora species, in comparison, produce a lower yield of EPA but they produce comparatively high levels of palmitic, oleic and linoleic acids, which may be of industrial value (Table 5).
The results of the fatty acid analysis confirm that C16:0 palmitic acid, C18:1n-9 oleic acid, C18:2n-6 linoleic acid, C20:4n-6 arachidonic acid and C20:5n-3 eicosapentaenoic acid were dominant fatty acids in mycelia of the studied Halophytophthora and Salispina species. Some of these fatty acids are beneficial to human health; oleic acids in lowering LDL-cholesterol levels which can lead to cardiovascular diseases (Pérez-Jiménez et al. 2007), linoleic acid as a structural component of cell membranes, an energy source (Whelan and Fritsche 2013) and a precursor of longer chain PUFAs, ARA and EPA in the prevention of coronary heart diseases, obesity and hypertension (Ye and Ghosh 2018). This highlights the potential of Halophytophthora and Salispina species as alternative sources of this fatty acids.
This study is the first to analyse C18:1n-7 vaccenic acid, C20:1 eicosenoic acid, C24:1 nervonic acid, C20:2n-6 eicosadienoic acid, C22:4n-6 adrenic acid, C20:4n-3 eicosatetraenoic acid and C22:5n-3 docosapentaenoic acid in mycelia of selected Halophytophthora species and Salispina spinosa. Yields of these fatty acids were low (<1.28% of TFA, <9.82 mg l−1 yield), but some might be beneficial to human health, for example, vaccenic acid in suppressing tumor growth and coronary heart disease (Field et al. 2009), and nervonic acid in improving oligodendrocyte function (Lewkowicz et al. 2019).
Table 5 summarises the fatty acid profiles of Halophytophthora and Salispina species based on results of this study and those from the literature (Caguimbal et al. 2019; Devanadera et al. 2019; Pang et al. 2016). This is also the first study to screen the fatty acid profiles of H. batemanensis and H. exoprolifera. In particular, H. exoprolifera produced a different fatty acid profile from other Halophytophthora spp. and S. spinosa. The proportion of fatty acids, i.e. percentage of total fatty acid, produced by the different Halophytophthora and Salispina species and isolates of the same species varied; 10%–17% oleic acid was produced by H. avicenniae, 8–15% by H. vesicula and 4–15% by S. spinosa. For linoleic acid, H. avicenniae produced 16–20%, H. vesicula 13–25% and S. spinosa 22–33%. ARA and EPA yields varied between Halophytophthora species, and within different isolates of H. avicenniae and S. spinosa analysed in this study and those in Pang et al. (2016). This may be attributed to the media (nutrient concentration, salinity) used in the different studies. Say et al. (2017) showed that nutrient composition, salinity and pH of the fermentation medium affected the type and quantity of fatty acids produced by a Halophytophthora isolate S13005YL1-3.1: 8, 10 and 13 fatty acids were produced in V8 SWD-A (pH 8, salinity 30), V8 SWD-B (pH 6, salinity 10) (V8 SWD: 20% clarified V8 juice, 80% sterile distilled water) and PYG (4 g l−1 peptone, 4 g l−1 yeast extract, 10 g l−1 glucose, 50% sterile seawater or 25 g l−1 sea salt) media, respectively. These variations in fatty acid profiles suggest that further studies are required to determine the best conditions and isolates for greater yields of these essential fatty acids.
In conclusion, Halophytophthora spp. and S. spinosa produced a wide range of saturated and unsaturated fatty acids in their mycelia and with varying yields. The dominant fatty acids were C16:0 palmitic acid, C18:1n-9 oleic acid, C18:2n-6 linoleic acid, C20:4n-6 arachidonic acid and C20:5n-3 eicosapentaenoic acid, the latter two being essential fatty acids for human diet may be of great industrial value. In thraustochytrids, lipids were found to be possible energy sources for their motile cells (i.e. amoeboid cells) and during starvation (Jain et al. 2007), and a similar function may also apply to Halophytophthora and Salipina species. Marine thraustochytrids have been successfully used to replace dietary fish oil in feed of Atlantic salmon (Chang et al. 2020; Tibbetts et al. 2020). Thus, the results presented here show the potential for applications of Halophytophthora and Salispina in aquaculture feed, an area that requires further study and investment.
Funding source: Ministry of Science and Technology, Taiwan
Award Identifier / Grant number: MOST 104-2621-B-019-004-
About the authors
Chun-Jui Su obtained his MSc at National Taiwan Ocean University studying fatty acids of marine Oomycota under the supervision of Prof. Ka-Lai Pang.
Wen-Ting Ju obtained his MSc at National Taiwan Ocean University studying fatty acids of marine Oomycota under the supervision of Prof. Ka-Lai Pang.
Michael W.L. Chiang obtained his MPhil degree from the City University of Hong Kong in 2002 and is currently a technical officer in the Department of Chemistry of the same university. His technical expertise lies in biological electron microscopy and ecotoxicology.
E.B. Gareth Jones devoted 60 years to the study of marine fungi, obtained his PhD from the University of Leeds, UK and was awarded the DSc from the University of Wales. Has worked extensively in Asia and supervised circa 100 PhD/MSc students by research and published 600 research articles. Besides marine mycology he has studied marine biofouling, biodeterioration of materials, and wood decay by fungi. Recently he initiated the website www.marinefungi.org which documents our current knowledge of marine fungi.
Ka-Lai Pang obtained his BSc and PhD degrees from the City University of Hong Kong in 1998 and 2001, respectively. Prof. Pang studies the biology of marine fungi and fungus-like organisms and endophytic fungi associated with mangrove plants and macroalgae.
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Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
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Research funding: Ka-Lai Pang thanks for the financial support provided by the Ministry of Science and Technology, Taiwan (MOST 104−2621−B−019-004−).
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Conflict of interest statement: The authors declare no conflicts of interest regarding this article.
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© 2021 Chun-Jui Su et al., published by De Gruyter, Berlin/Boston
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