The Oleaginous Yeast Meyerozyma guilliermondii BI281A as a New Potential Biodiesel Feedstock: Selection and Lipid Production Optimization

Abstract

A high throughput screening (HTS) methodology for evaluation of cellular lipid content based on Nile red fluorescence reads using black background 96-wells test plates and a plate reader equipment allowed the rapid intracellular lipid estimation of strains from a Brazilian phylloplane yeast collection. A new oleaginous yeast, Meyerozyma guilliermondii BI281A, was selected, for which the gravimetric determination of total lipids relative to dry weight was 52.38% for glucose or 34.97% for pure glycerol. The lipid production was optimized obtaining 108 mg/L of neutral lipids using pure glycerol as carbon source, and the strain proved capable of accumulating oil using raw glycerol from a biodiesel refinery. The lipid profile showed monounsaturated fatty acids (MUFA) varying between 56 or 74% in pure or raw glycerol, respectively. M. guilliermondii BI281A bears potential as a new biodiesel feedstock.

Oleaginous yeast Meyerozyma guilliermondii shows fermentative metabolism of sugars in the biosynthesis of ethanol and converts raw glycerol and cheese whey permeate into polyunsaturated fatty acids

“…Shake flask cultivations were performed using different carbon sources and C/N ratios to test the ability of M. guilliermondii BI281A to convert the substrates into biomass and to produce lipids or other metabolites and to define ideal growth conditions that could be used to run experiments in bioreactors. The ability of M. guilliermondii BI281A cells to produce lipids was first reported using fluorescence intensity using Nile Red dye by high throughput screening (HTS) methodology . The yeast M. guilliermondii BI281A showed higher Relative Fluorescence Units (RFU) than Y. lipolytica , the positive control, proving that this yeast is able to accumulate oil intracellularly .…”

“…The ability of M. guilliermondii BI281A cells to produce lipids was first reported using fluorescence intensity using Nile Red dye by high throughput screening (HTS) methodology . The yeast M. guilliermondii BI281A showed higher Relative Fluorescence Units (RFU) than Y. lipolytica , the positive control, proving that this yeast is able to accumulate oil intracellularly . Other authors used fluorescence staining and observed lipid particles using Nile Red dye in M. guilliermondii Pcla22 and demonstrated that this yeast can synthetize intracellular lipids .…”

“…This strain was isolated from bromeliads of the Itapuã State Reserve (Viamão, RS, Brazil, 30° 04′ 52″ S, 51° 01′ 24″ W). The strain identification was performed using molecular biology tools and details of this identification can be found in a previous work . Certified stocks of this yeast are kept in the Department of Microbiology of Federal University of Rio Grande do Sul (Porto Alegre, Brazil), which kindly supplied the stock used in this work.…”

“…However, several other yeast species have been researched in order to expand the possibilities of PUFA production, such as strains of Lipomyces starkeyi , Rhodosporidium toruloides , Rhodotorula glutinis , Candida curvatus , and Cryptococcus curvatus , which have been intensively studied regarding the optimization of their cultivation conditions and genetic modifications . The nonpathogenic, ascomycete yeast Meyerozyma guilliermondii , previously known as Pichia guilliermondii , has been reported as an oleaginous strain . However, only a few studies focused on its metabolism, whereas its ability to produce PUFA (and their fatty acid characteristics) and other biotechnologically‐important metabolites, such as ethanol, are little known.…”

“…Furthermore, the metabolism of ethanol synthesis by M. guilliermondii is still unknown. The production of this biofuel is a relevant technology that can be used as fossil fuels substitute and has been extensively studied using Saccharomyces cerevisiae as a biological model …”