Ethanol production from kitchen waste by wild type yeast isolated from natural sources

Abstract

It is time we think about changing to alternate fuel and make energy production procedures greener. Bioethanol production by microbes is one step towards it. In this study, yeast from easily available food sources was used to produce bioethanol by using domestic food waste as substrate. This work was designed to bioconvert the lignocellulosic biomass to ethanol by the action of yeast and bacteria. Grapes, cow dung, rice water, vegetable peels and soil were chosen to isolate wild-type yeast for it to be the ethanol producing organism. The strain found went through isolation, identification, stress tolerance tests and detailed characterization and optimization before being used on inexpensive substrates to produce low cost ethanol. Considering all the characteristics it was assumed that the strains isolated belonged to Saccharomyces spp. The principal goal of this study was to produce ethanol at a low cost by the integration of highly efficient yeast strain into the substrate that is considered as lignocellulosic household waste. Optimization of fermentation was done at various temperature, pH, rotation per minute, substrate size and the optimum fermentation condition was found to be at pH 6, 30°C, 120 rpm having small cut substrates. An increase in the production was seen after the substrates were treated with starch hydrolyzing and cellulolytic bacteria where the highest increase of ethanol production was from 2.93 %v/v to 6.99 %v/v. These bacteria converted the complex carbohydrates to simpler ones which the yeast utilized to produce the maximum amount of ethanol. The maximum ethanol produced by yeast using vegetable peels was 6.99 %v/v after 48 hours of incubation at 30°C, 120 rpm after bacterial treatment. This ethanol formed can be used as biofuel as well as disinfectant which will reduce our dependence on fossil fuel which are polluting our environment in a dangerous way.