SCREENING AND CHARACTERIZATION OF POTENTIAL ETHANOL OXIDIZING YEAST ISOLATES FROM SUGAR-RICH ORGANIC WASTE RESOURCES USING SCHIFF’S-BASE REACTION

Abstract

Alcohol dehydrogenase is an oxidoreductase enzyme that carries both alcohol oxidation and aldehyde/ketone reduction activity. Alcohol dehydrogenase (ADH) activity of yeast cells were essential for industrial applications. Sugar-rich organic waste resources including spoiled fruits, fruit peel waste, spoiled vegetables, raw and composed sludge from the dairy industry, and cane molasses spill from the sugar industry, provide a favorable habitat for ethanol-oxidizing microorganisms with ADH activity. The total ethanol oxidizing microbial population of organic waste resources differs considerably from the overall microbial community. Yeast from the natural habitats has a great potential for developing novel enzymes for industrial uses. Under this backdrop, the present study was focused on screening and characterization of potential ethanol oxidizing yeast strains from sugar-rich organic waste resources. Totally seventeen ethanol oxidizing yeast strains belongs to Pichia sp. (9 strains), Candida sp. (2 strains) and Debaryomyces sp. (2 strains), Hanseniaspora sp, Lachancea sp, Torulaspora sp, and Magnusiomyces sp. have been identified. The ability of strains to oxidize ethanol into acetaldehyde was verified by the Schiff’s-base reaction through p-rosaniline assay. The selected five potential ethanol oxidizing strains were identified by 18S rRNA gene sequence as Pichia kluyveri FYES5, Pichia kudriavzevii FYES6, Pichia kudriavzevii VYES2, Candida mengyuniae CSYES1, and Magnusiomyces capitatus CSYES2 with the p-r index of 2.64±0.40, 3.79±0.54, 3.73±0.69, 2.28±0.24, and 2.87±0.58 respectively at 28°C. This is the first report to identify ethanol oxidizing yeast strains from sugar-rich organic waste resources and by this study found that the strain Candida mengyuniae has a better ability to oxidize ethanol.