Isolation and Characterization of Indigenous Yeast Species from Yoghurt and Sugarcane Juice for Production of Bio-ethanol

Abstract

The yeast strains possess appreciable characteristics for ethanol production. Moreover, Bio-ethanol production from renewable sources to be used is now an increasing demand worldwide due to continuous depletion of fossil fuels, economic and political crises, and growing concern for environmental safety. The main objective of this study was to isolate indigenous yeast strains from yoghurt and sugarcane juice samples which may further be utilized in bio-ethanol production. A total of 20 samples were collected randomly from local markets of different localities of Karachi. These samples were screened using selective medium Yeast Extract Peptone Dextrose Agar (YEPD), from where fifteen yeast strains were isolated. Differential tests were applied, including morphological, cultural and biochemical characteristics, which facilitate the opportunity for identification of the yeast strains. More yeast strains were isolated from sugar cane samples as compared to yoghurt. These strains have shown the potential to efficiently utilization of the Glucose, Fructose, Sucrose, Maltose and Urea as the carbon source. A yeast strain able to produce a good yield of fermentation of sugars into ethanol was identified. The isolation of these fermenting yeasts could attract widespread interest worldwide, as they can be used in the cost-effective production of bio-ethanol. These isolates could be used at the industrial level for fermentation of various raw materials in order to obtain an increased production of bio-ethanol.