L-asparaginase and Biosurfactants Produced by Extremophile Yeasts from Antarctic Environments

Abstract

In this study, L-asparaginase and biosurfactants production by yeasts isolated from marine and terrestrial Antarctic environments was investigated. L-asparaginase production was determined by assessing enzyme activity and biosurfactants production was evaluated according to fermentation parameters and biosurfactant characteristics, including those determined by FTIR. Biosurfactant analysis results revealed all 14 yeast tested presented at least one characteristic of biosurfactant or bioemulsification activity. The yeasts Meyerozyma guilliermondii L21, Candida glaebosa L75, Cryptococcus victoriae L92 and Leucosporidium scotti L120 presented the greatest potential to produce biosurfactant and were selected for additional testing related to biosurfactants production and evaluation of L-asparaginase production. Additional tests found critical micellar concentration (CMC) values of 500-700 mg/L and high stability (pH 2-12, salinity of 0.5-10% and temperature of 20-100°C); the highest productivity was 0.17 and 0.28 g/L·h, respectively, for Candida glaebosa L75 and Leucosporidium scotti L120. Also, the use of polyurethane as solid-state fermentation (SSF) support proved to be useful in L-asparaginase production; all selected yeasts yielded at least 0.9 U/g of inert support and Leucosporidium scotti L120 was the most efficient, providing 1.4 U/g support. The evaluation of Antarctic yeast confirmed their potential to produce L-asparaginase and biosurfactants, demonstrated L-asparaginase production by yeasts via SSF and revealed satisfactory production of biosurfactants by yeasts from poorly explored cold environments.