Isolation and Characterization of Ethanol and Thermotolerant Yeast Isolates from Different Sources in Atbara Town – River Nile State - Sudan

Abstract

Thirty yeasts isolates were isolated from five fruits namely grapes (Vitis vinifera), apple (Malus domestica), date palm (Phoenix dactylifera), banana (Musa paradisiaca) and fermented sorghum dough (Ajeen) collected from Atbara market. The viable cell count of yeasts isolates was enumerated. All the yeast isolates were first screened for carbohydrate fermentation using Durham tube fermentation method in yeast extract peptone dextrose broth. Five isolates (SUDA, SUDV, SUDMU, SUDP and SUDDD) which were relatively high fermentative were selected for further study. All the selected isolates were identified morphologically, using macroscopic and microscopic features. The yeast isolates were also screened for ethanoland thermo - tolerance. Further, the optimum pH was determined. The results of this investigation revealed that the yeast colony forming unit was ranged from 99 x104 cfu/ml to 118 x104 cfu/ml. For the test of temperature, growth was detected up to 40°C with optimum temperature at 37°C for all isolates, for ethanol concentration 15% was optimum for all isolates except SUDMU and SUDP was at 20% and 25%, respectively. The optimum pH was ranged from 5-6. The aim of this study is to isolate and characterize ethanol, and thermo - tolerant yeast for industrial purposes.