title: Culturable diversity and biochemical features of thraustochytrids from coastal waters of Southern China.
abstract: Thraustochytrids are ubiquitous marine osmo-heterotrophic fungi-like microorganisms with only about 40 identified species till now. In this study, a total of 60 thraustochytrid strains were isolated from marine coastal habitats. Analysis of 18S rRNA gene sequences revealed that they belonged to three genera, i.e., Schizochytrium, Aurantiochytrium, and Thraustochytrium. All of the isolates were found to show considerable cellulolytic and lipolytic activities. Strains of Aurantiochytrium sp. and Thraustochytrium sp. were found to produce the highest levels of extracellular polysaccharides (EPS), which reached 345 μg ml(-1) in the growth media. Fourier transform infrared (FTIR) spectra of the EPS samples derived from two thraustochytrids (PKU#Sed1 and #SW1) displayed peaks for carbohydrates, proteins, lipids, uronic acids, and nucleic acids. Fatty acid profiles of four thraustochytrids comprised of palmitic acid (C16:0) and docosahexaenoic acid (DHA) as their major constituents. Schizochytrium sp. demonstrated the highest DHA production at 44 % of total fatty acids (TFA) with biomass and DHA yield of 7.1 and 1.6 g l(-1), respectively, on the fourth day of growth. All the four isolates exhibited considerable production of palmitic acid (16:0) in their fatty acid profiles ranging from 35 to 50 % TFA. This is the first report on extracellular enzymes, EPS, and DHA production from thraustochytrids isolated from the coastal habitats of China.
authors.affiliation: School of Environment and Energy, Peking University Shenzhen Graduate School, Shenzhen, 518055, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Purnima
authors.initials: P
authors.lastname: Singh
authors.forename: Yuan
authors.initials: Y
authors.lastname: Sun
authors.forename: Shengji
authors.initials: S
authors.lastname: Luan
authors.forename: Guangyi
authors.initials: G
authors.lastname: Wang
mesh_terms: D044822:Biodiversity; D002681:China; D008055:Lipids / Q000032:analysis; D008969:Molecular Sequence Data; D009696:Nucleic Acids / Q000032:analysis; D011134:Polysaccharides / Q000032:analysis; D011506:Proteins / Q000032:analysis; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D058009:Stramenopiles / Q000737:chemistry / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D014574:Uronic Acids / Q000032:analysis
chemical_list: D008055:Lipids; D009696:Nucleic Acids; D011134:Polysaccharides; D011506:Proteins; D012337:RNA, Ribosomal, 18S; D014574:Uronic Acids