Saccharomyces cerevisiae: A Facultative Anaerobe for Ethanol Fermentation Using Organic Waste

The excessive exploitation of natural resources such as fossil fuels by humans has led to significant environmental changes, the greenhouse effect, and the depletion of the ozone layer. Hence, there is a need to reduce the dependency on fossil fuels and look for alternative and renewable energy sources. Bioethanol produced from the fermentation of organic wastes is a promising solution to the growing energy needs the world over. For the industrial production of bioethanol from organic substrates, it is found that Saccharomyces cerevisiae is the most suitable microorganism due to its versatile characteristics, such as ease of growing and maintaining its cultures, effective sugar utilization, high ethanol fermentation capability, increased tolerance to ethanol in the fermentation medium, ease of genetic manipulation to increase ethanol yields, and ability to survive in low oxygen concentrations. However, a few challenges could be encountered during the industrial production of ethanol using S. cerevisiae as the fermenting microbe, such as the formation of inhibitory compounds in the fermentation medium, the complex composition of the organic substrate employed, product inhibition, and contamination of the fermentation medium by other microbes. A few ways in which bioethanol fermentation from organic waste can be increased include strain selection and genetic manipulation of the S. cerevisiae strains with increased ethanol fermentation ability and high ethanol tolerance, enzymatic pretreatment of lignocellulosic biomass prior to the commencement of the fermentation process, and addition of antimicrobial agents, antibiotics, or bacteriocins into the medium.