Screening for glycosidases from yeast isolated from lake bogoria, Kenya

Abstract

Extreme environments are inhabited by diverse flora and fauna. These organisms are adapted to these extreme environments by producing extremozymes. Extremozymes are active and stable under these extreme harsh conditions. These enzymes are useful in biotechnological applications and industrial processes because they are capable of working outside the range of mesophilic enzymes. Although unique enzymes for biotechnological! industrial applications may be derived from any living organism, there is currently a paucity of information regarding availability of biotechnological enzymes from therrnohaloakaliphilic yeasts. The aim of this study was to isolate and identify yeast from Lake Bogoria, Kenya and screen them for production of glycosidases. Water and soil samples were collected and streaked on selective media to isolate yeasts. The isolates were screening for production of glycosidases using fluorigenic 4 - methyllumberiferyl glycosides as substrates. A unique yeast isolate was obtained and characterized morphologically, physiologically and biochemically. This isolate was further characterized by amplification and analysis of the Intemally Transcribed Spacer (ITS) DNA sequence. A brown yeast isolate, LBK 8 was isolated. The Isolate showed appreciable levels D galactosidase, P-D xylosidase or a-D Glucosidase and P-D Glucosidase enzymes. The ability of the isolate to grow on media having Beta-Glucan, Polylactic acid, pectin, carboxymethylcellulose and Raffinose as the sole carbon source is an indication of the presence of enzyme systems to break down the respective glycosidic bonds. The LBK 8 yeast isolate was found to grow best on alkaline media when incubated at higher ----~ temperature. Though phylogenetic relationship analysis groups the isolate together with Aspergillus species, the isolate shows significant distance from the known Aspergillus The study shows that Lake Bogoria, Kenya an extreme environment has potential being a source of new thermo alkaliphilic yeast. The isolate has potential of being a source of alkaliphilic thermo stable glycosidase enzymes for biotechnological application.