Antarctic thraustochytrids: Producers of long‐chain omega‐3 polyunsaturated fatty acids

Abstract

Thraustochytrids have been isolated from different aquatic systems; however, few studies have reported their occurrence in Antarctica. In this study, 13 strains close to strains belonging to the genera Oblongichytrium, Thraustochytrium, and Aurantiochytrium were isolated from seawater samples collected near the Antarctic Base Professor Julio Escudero (S 62°12′57′ E 58°57′35″). Docosahexaenoic acid (DHA) was found in the total lipids of all the isolates; DHA content of the biomass (dry weight) varied between 3.3 and 33 mg/g under the growth conditions for isolation. Five of the Antarctic thraustochytrids were able to accumulate lipids at levels higher than 20% w/w. Two strains, RT2316-7 and RT2316-13, were selected to test the effect of the incubation temperature (at 5°C for 14 days and at 15°C for 5 days).Incubation temperature had little effect on the lipid content and biomass yield; however, its effect on the fatty acid composition was significant (p < .05). The low incubation temperature favored the accumulation of eicosapentaenoic acid (EPA), palmitic acid and stearic acid in the total lipids of RT2316-7. Percentage of EPA, DHA and the omega-6 fatty acid dihomo-γ-linolenic acid of total fatty acids of RT2316-13 was higher at the low incubation temperature. RT2316-13 accumulated the highest lipid content (30.0 ± 0.5%) with a carbon to nitrogen mass ratio equal to 16.9. On the contrary, lipid accumulation in RT2316-7 occurred at high concentration of the nitrogen sources (monosodium glutamate or yeast extract). The capability to accumulate lipids with a fatty acid profile that can be tuned through cultivation temperature make the Antarctic thraustochytrid RT2316-13 a candidate for the production of lipids with different uses.

Physicochemical Characteristics of Protein Isolated from Thraustochytrid Oilcake

“…Thraustochytrids, marine unicellular, heterotrophic protists, are abundant in marine habitats of tropical, temperate and Antarctic waters [10][11][12]. They are important components of mangrove forest microbial ecosystems, recycling marine nutrients into a broad variety of biomolecules used as nutrients for both marine and terrestrial species.…”

Dynamic flux balance analysis of biomass and lipid production by Antarctic thraustochytrid Oblongichytrium sp. RT2316‐13

“…RT2316-13 was used. Details of isolation and identification of this marine microorganism were previously published (Shene et al, 2019). The stock cultures were kept frozen at −80°C in 50% glycerol (vol/vol).…”

“…Total lipids in the freeze-dried biomass (50 mg) were extracted and methylated as described previously (Shene et al, 2019). Fatty acid composition of the methylated lipid extract was determined using a gas chromatograph (GC-2010 Plus; Shimadzu, Kyoto, Japan; Shene et al, 2013).…”

“…This study reports on biomass and lipid production in batch culture of a newly isolated Antarctic thraustochytrid Oblongichytrium sp. RT2316-13 (Shene et al, 2019), with a particular focus on synthesis of DHA and EPA. A GEM was used to interpret experimental observations.…”

Cultivation and diversity analysis of novel marine thraustochytrids

“…Thraustochytrids may be adapted to diverse habitats, such as coastal, offshore and estuarine waters (Liu et al 2013;Ueda et al 2015), sediments (Wong et al 2005), algae (Damare 2014) and mangrove litter debris (Bremer 1995). Several new thraustochytrid strains with the capability to produce abundant valuable metabolites were isolated from Antarctica (Shene et al 2020), the deep sea (Raghukumar et al 2001) and invertebrates (Rabinowitz et al Fig. 1 A phylogenetic tree of culturable thraustochytrids using Neighbor-Joining method with Rhodotorula mucilaginosa TJUWZ7 and Crypthecodinium cohnii as outgroups based on 18S rRNA gene sequences.…”