Sustainable arabitol production by a newly isolated Debaryomyces prosopidis strain cultivated on biodiesel-derived glycerol

The purpose of this research was the bioconversion of biodiesel-derived glycerol to arabitol through the adoption of sustainable bioprocessing.Arabitol production by Debaryomyces prosopidis FMCC Y69 was significantly affected by initial glycerol concentrations.The highest arabitol concentration of 45.5 g/L was achieved in the case of 120 g/L initial glycerol combined with the highest yield(0.379 g arabitol/g initial glycerol).The yeast strain showed a non-typical oleaginous behavior with low accumulation of lipids(up to 20.9%w/w)despite nitrogen-limited condition that prevailed in the fermentation media.Endopolysaccharides(IPs)were considerably high with a yield on the produced dry cell weight(YIPs/X)(=40.9%w/w)when 85 g/L of glycerol was utilized as the starting material.The fermentation efficiency was further improved when the optimal carbon to nitrogen(C/N)ratio was applied.More specifically,arabitol production was maximized(reaching 56.5 g/L)at a C/N ratio of 158 moles/moles while yield and productivity were also enhanced with respective values of 0.48 g arabitol/g consumed glycerol and 0.112 g/L.h.The increase in C/N ratios led to a decrease in cell dry weight(DCW)concentrations,which is rationally associated with decreased nitrogen availability in the growth medium.YIPs/X values were remarkably high(23.1–26.1%w/w)at the end of each fermentation with the highest concentration in absolute values of 7.3 g/L achieved at the lowest C/N ratio employed(i.e.,79 moles/moles).This study demonstrated the efficient arabitol production along with other value-added metabolites,such as IPs and cellular lipids,implementing biotechnology and renewable resources and thus contributing to the development of circular economy technologies.