Isolation and Characterization of Amylase-Producing Osmophilic Yeasts from Fruits

Amylases are key enzymes widely used in industries such as food processing, biofuel production, textiles, and pharmaceuticals due to their role in breaking down starch into simpler sugars. Bacterial and fungal sources are commonly employed for amylase production, osmophilic yeasts remain relatively underexplored despite their potential to withstand challenging industrial conditions. This study investigated the isolation and characterization of amylase-producing osmophilic yeasts from pineapple and banana fruits. The fruits were allowed to ferment naturally to enrich for osmophilic yeast populations. Following serial dilution and culturing on Potato Dextrose Agar, seven distinct yeast isolates were obtained. All isolates tested positive for catalase and amylase activity, confirmed by clear zones of starch hydrolysis on selective media. Microscopic and biochemical tests were conducted to identify yeast morphology, followed by molecular characterization. Amylase production was quantified using the 3,5-dinitrosalicylic acid (DNS) method, and fermentation parameters were optimized to improve enzyme production. The two yeasts characterized molecularly were identified to be Pichia kudriavzevii with 99.37 and 99.36% similarly with isolates in Gen bank with accession number PP565176. 1 and MT234388.1. The effects of various carbon and nitrogen sources, starch concentrations were evaluated. Among the substrates tested, sucrose and yeast extract supported the highest value growth and enzyme production. The findings indicate that osmophilic yeasts isolated from fruits can serve as promising producers of amylase, with potential applications in industrial processes that involve high sugar concentrations . These results contribute to the search for alternative microbial sources of enzymes and support the broader use of yeasts in industrial biotechnology.