Evaluation of Lipid Production by The Yeast Strains Isolated From Beaches of Qeshm Island

BACKGROUND AND OBJECTIVESMicrobial lipids are of special importance in the food and pharmaceutical industries. Because thecomposition of their fatty acids is comparable to vegetable oils, they can be substituted by vital dietarylipids. Oleaginous yeast can be used to produce large quantities of valuable products at a low cost andis unaffected by weather and seasonal conditions. In general, yeasts are considered better than bacteria,molds, and algae due to their comparatively fast growth rate (in single cells), capacity to synthesizelipids in individual cells, and ability to absorb carbon sources from diverse industry byproducts .This study focused on isolating yeast strains from water, soil, and plant samples to investigate theirlipid biosynthesis ability and find a proper extraction method.MATERIALS AND METHODSsamples were cultured on YPD agar containing chloramphenicol at ۲۵ °C for at least ۷۲ hours, andsubsequently evaluated for colony formation at ۲۴hr intervals. Yeasts were isolated and Sudan BlackB staining of the cells was carried out to observe the intracellular lipid particles. The screened yeastswere incubated in media containing KH۲PO۴, MgSO۴, (NH۴)۲SO۴, yeast extract, and glucose at ۲۵ °Cfor ۴۸ hours. Different cell disruption techniques and two solvent extraction methods were examined.Eventually, Cell disruption of the biomass was carried out by appropriate methods and lipid extractionwas done using the proper solvent.RESULTS AND DISCUSSIONTen yeast strains were isolated and four of them were selected based on the presence of intracellularlipid particles. They were identified, registered, and received Access numbers in the Iranian ResearchOrganization for Science and Technology microbiological collection. Based on the results, freezethawing(repeated four times) followed by acid treatment at ۶۰ °C was selected for cell disruption, andhexane was selected for lipid extraction. maximum lipid production was observed in the identifiedstrains Cystobasidium benthicum PTCC۵۳۳۸ and Filobasidium magnum PTCC۵۳۳۹. Hortaeawerneckii PTCC۵۳۳۷ and Debaryomyces nepalensis PTCC۵۳۳۶ produced lipids less than ۲۰% drycell weight.CONCLUSIONThe Qeshm Island ecosystem has appropriate potential for the presence of oleaginous yeast strains.