Evaluation of cell disruption methods in the oleaginous yeasts Yarrowia lipolytica QU21 and Meyerozyma guilliermondii BI281A for microbial oil extraction.

The interest for oleaginous yeasts has grown significantly in the last three decades, mainly due to their potential use as a renewable source of microbial oil or single cell oils (SCOs). However, the methodologies for cell disruption to obtain the microbial oil are considered critical and determinant for a large-scale production. Therefore, this work aimed to evaluate different methods for cell wall disruption for the lipid extraction of Yarrowia lipolytica QU21 and Meyerozyma guilliermondii BI281A. The two strains were separately cultivated in 5 L batch fermenters for 120 hours, at 26 ºC and 400 rpm. Three different lipid extraction processes using Turrax homogenizer, Ultrasonicator and Braun homogenizer combined with bead milling were applied in wet, oven-dried, and freeze-dried biomass of both strains. The treatment with the highest percentage of disrupted cells and highest oil yield was the ultrasonication of oven-dried biomass (37-40% lipid content for both strains). The fact that our results point to one best extraction strategy for two different yeast strains, belonging to different species, is a great news towards the development of a unified technique that could be applied at industrial plants.

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

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.