Evaluation of Production, Stability and Activity of Biosurfactants from Yeasts with Application in Bioremediation of Oil-polluted Environment

作者：Csutak Ortansa; Stoica Ileana; Vassu Tatiana^*

来源：Revista de Chimie, 2012, 63(10): 973-977.

• yeasts
• biosurfactant
• bioremediation
• stability
• antimicrobial

Biosurfactant production and activity were evaluated for yeast strains Rhodotorula glutinis RG1, RG2, RG4 and RG5, Issatchenkia orientalis 103 and Candida rugosa CR6 isolated from oil-polluted soil from Ploiesti, Romania. Optimized biosurfactant yields were obtained on Yeast Peptone media with 1% n-alkanes after 48 h incubation for RG1 on n-tetradecane, RG2 and CR6 on n-hexadecane and after 72 h for IO3 on n-tetradecane, RG4 and RG5 on n-decane. Emulsification activity towards petroleum was monitored during stability studies. Biosurfactants showed good stability at 4 degrees C and pH values 6.0 to 10.0. An increase of environmental pH to 8.0 correlated with high emulsification index. Augmenting salinity had negative impact especially for strain CR6, indicating that surface tension might play an important role in hydrocarbon emulsification and assimilation. Biosurfactants were involved in interactions between RG1, RG4, RG5 cells and alkanes, while for RG2 an additional cell surface related mechanism seems to be involved. Dividing cells appeared in IO3 samples and alkanes were quickly assimilated into CR6 cells. Since the analyzed biosurfactants were active in petroleum and alkanes emulsification and assimilation into yeast cells, they present high potential for application in bioremediation of polluted environment. Moreover, antimicrobial assays against potential pathogen yeasts revealed halos with low growth rates. Microscopic examination showed cells with large vacuoles, emerging pseudohyphae or true hyphae due to changes of pH and nutritional sources.

• 出版日期2012-10