Construction of a novel cold-adapted oleaginous yeast consortium valued for textile azo dye wastewater processing and biorefinery

A new lipid-accumulating and cold-adapted oleaginous yeast consortium MG-Y-SH which stands for molecularly identified species Meyerozyma guilliermondii, Yarrowia sp. and Sterigmatomyces halophilus was successfully constructed in this study. Its total saturated fatty acid content (34.64 +/- 0.95%) was higher than that of jatropha oil (21.52%). The oil obtained from oleaginous yeast consortium MG-Y-SH is advantageous for biodiesel production, since it contains low amount (21.48 +/- 1.1%) of polyunsaturated fatty acids (C18:2 and C18:3). Lipase, which is a biocatalyst for the production of biodiesel by oleaginous yeasts, reached its highest specific activity of 8.35 +/- 0.14 U/mg (extracellular) and 7.901 +/- 0.12 U/mg (intracellular) after 36 h of incubation compared to the individual strains. Seven dye mixtures, six dyes in each group, were constructed and the maximum decolorization efficiency ranged between 55.81% (mixture III) and 80.56% (mixture VI) within 24 h of treatment with MG-Y-SH at 18 degrees C and under static conditions. The maximum decolorization efficiency by MG-Y-SH reached 100% at 100 mg/L Reactive Red 120 (RR120) within 3 h. Based on our investigation and analysis on those metabolites drawn from the mass spectrum as well as various induced enzymes, a possible dye biodegradation pathway linked to fatty acid synthesis was proposed. The results of phytotoxicity indicate a capability of MG-Y-SH in converting the toxic azo dye RR120 into some non-toxic metabolites, suggesting MG-Y-SH as a promising multipurpose oleaginous yeast consortium suitable for biodiesel production in the future, while degrading recalcitrant dyes and lignin valorization in cold environments.

Automated summary

The lipid-accumulating and cold-adapted oleaginous yeast consortium MG-Y-SH showed higher saturated fatty acid content and lower polyunsaturated fatty acid content compared to jatropha oil. It demonstrated efficient decolorization of dyes and the capability to convert toxic compounds into non-toxic metabolites, making it a promising candidate for biodiesel production and environmental remediation in cold environments.