The Isolation and Identification of Stress Tolerance Ethanol-fermenting Yeasts from Mozzarella Cheese Whey

Bioethanol conversions has long been considered as a possible solution for whey utilization. The existence of wild ethanol-fermenting yeasts that able to hydrolyze lactose become an important thing. Aims of the research was to isolate and identified the potential ethanol-fermenting yeasts from mozzarella cheese whey. Research done experimentally and analyzed descriptively. Yeast candidates isolated from mozarella cheese whey with pour plate method and purified on Potato Dextrose Agar (PDA) with the addition of 3% Yeast Extract and 10 ppm of Amoxycillin. The candidates were tested to stress tolerance towards various sugar and ethanol contents. Ethanol-fermenting yeast candidates tested in converting whey into bioethanol by inoculating 2% isolates into mozzarella cheese whey and incubated in room temperature (26-28°C) for 48 hours, then the ethanol contents tested by Gas Chromatography. The isolate that gave the highest ethanol contents identified using RapID Yeast Plus System. Results showed that there are 5.8 x 105 cfu/ml yeasts population in mozzarella cheese whey with four isolates that has different macroscopic character. Four candidate showed endurance towards 30% sugar and 20% ethanol contents and isolate W2 chosen as best isolate that produce the highest ethanol contents of 1,515.973 ppm. RapID Yeast Plus System has identified the isolate W2 has 96.43% similarity with Candida lambica .