Biotechnological production of polyols through conversions of crude glycerol by newly isolated strains of the yeast Yarrowia lipolytica

The purpose of this study is to investigate the ability of newly isolated Yarrowia lipolytica strains to grow on crude glycerol, the main by-product of the industrial production of biodiesel. In particular, the ability of the yeasts to metabolize glycerol and produce dry cell weight (DCW) and secondary metabolites such as lipid, endopolysaccharides and polyols (e.g. mannitol, arabitol, erythritol) was assessed. Two newly isolated strains (LMBF Y-46 and LMBF Y-47) were used, while trials were performed in different initial glycerol concentrations (Glol0=40-120 g/L) and various initial pH values (3.0-7.0) in shake-flasks. It has been seen that polyols production increased with decrease of pH value into the medium. At low Glol0 concentrations (=40 g/L), almost exclusively mannitol was synthesized (i.e. the strain LMBF Y-46 produced ~20 g/L of mannitol at pH=3.0). When Glol0 increased, other polyols (i.e. erythritol and arabitol) were also produced in appreciable quantities. At a pH=3.5 and for Glol0~120 g/L, a total quantity of polyols ~57 g/L was synthesized for the strain LMBF Y-46. Cellular lipids in restricted quantities (8-14% in DCW) were produced, while cellular polysaccharides increased with the time reaching to values of c. 35-42% w/w in DCW at the stationary phase of growth. Acknowledgement The current investigation was financially supported by the project entitled “Adding value to biodiesel-derived crude glycerol with the use of Chemical and Microbial Technology” (Acronym: Addvalue2glycerol, project code Τ1ΕΔΚ-03002) financed by the Ministry of National Education and Religious Affairs, Greece (project action: “Investigate – Create – Innovate 2014-2020, Intervention II”).