Culturable Diversity and Lipid Production Profile of Labyrinthulomycete Protists Isolated from Coastal Mangrove Habitats of China.

Yaodong He,Guangyi Wang,Qiuzhen Wang,Yunxuan Xie,Huike Ye,Biswarup Sen

doi:10.3390/md17050268

Yaodong He, Guangyi Wang + Show 4 more

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https://doi.org/10.3390/md17050268

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Journal: Marine drugs	Publication Date: May 6, 2019
Citations: 27	License type: CC BY 4.0

Affiliation: Tianjin University, Hebei Agricultural University

Abstract

Labyrinthulomycete protists have gained significant attention in the recent past for their biotechnological importance. Yet, their lipid profiles are poorly described because only a few large-scale isolation attempts have been made so far. Here, we isolated more than 200 strains from mangrove habitats of China and characterized the molecular phylogeny and lipid accumulation potential of 71 strains. These strains were the closest relatives of six genera namely Aurantiochytrium, Botryochytrium, Parietichytrium, Schizochytrium, Thraustochytrium, and Labyrinthula. Docosahexaenoic acid (DHA) production of the top 15 strains ranged from 0.23 g/L to 1.14 g/L. Two labyrinthulid strains, GXBH-107 and GXBH-215, exhibited unprecedented high DHA production potential with content >10% of biomass. Among all strains, ZJWZ-7, identified as an Aurantiochytrium strain, exhibited the highest DHA production. Further optimization of culture conditions for strain ZJWZ-7 showed improved lipid production (1.66 g/L DHA and 1.68 g/L saturated fatty acids (SFAs)) with glycerol-malic-acid, peptone-yeast-extract, initial pH 7, 28 °C, and rotation rate 150 rpm. Besides, nitrogen source, initial pH, temperature, and rotation rate had significant effects on the cell biomass, DHA, and SFAs production. This study provides the identification and characterization of nearly six dozen thraustochytrids and labyrinthulids with high potential for lipid accumulation.

Highlights

Labyrinthulomycete protists are a group of marine fungus-like organisms classified within the kingdom Straminipila and are characterized by their ability to produce heterokont biflagellate zoospores and ectoplasmic networks [1]
The closest relatives of the 71 strains belonged to six different genera namely Aurantiochytrium, Botryochytrium, Parietichytrium, Schizochytrium, Thraustochytrium, and Labyrinthula (Table 2)
Aurantiochytrium, Schizochytrium, and Labyrinthula were the three most dominant genera that accounted for ca. 61%, 21.7%, and 13.2% of the total isolates, respectively (Table 2)

Summary

Introduction

Labyrinthulomycete protists are a group of marine fungus-like organisms classified within the kingdom Straminipila and are characterized by their ability to produce heterokont biflagellate zoospores and ectoplasmic networks [1] Based on their morphological and molecular characteristics, these osmoheterotrophic protists are grouped into three distinct groups namely thraustochytrids, labyrinthulids, and aplanochytrids [2,3,4,5]. These protists live as commensals or mutualists within the guts and tissues of marine invertebrates, and as saprobes on mollusk shells and their feces [5].

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