Microbial Synthesis of Polyhydric Alcohol by Saccharomyces cerevisiae

Aim: Synthesis of polyhydric alcohol from agricultural residue using Saccharomyces cerevisiae.

Study of Design: Submerged fermentation process, biomass yield and reducing sugar analysis, non-reducing sugar analysis, extraction and quantification of sugar monomers and polyhydric alcohols.

Place and Duration of Study: Microbiology Unit, Department of Biological Sciences, College of Natural and Applied Sciences, Fountain University Osogbo, Osun State, Nigeria between October 2015 and July 2016.

Methodology: Synthetic route for the production of polyhydric alcohol through sugar reduction under submerged fermentation using Saccharomyces cerevisiae MP2 isolated from fermented beverages was investigated. Biomass yield, reducing sugar concentration (DNS method) and non-reducing sugar (Anthrone method) were analysed. The crude extract obtained after fermentation period was subjected to derivatisation; thus sugars (reducing and non-reducing sugars) and polyhydric alcohol were quantified using Gas Chromatography Flame Ionization Detector.

Results: Biomass yield and reducing sugar concentration decreased as fermentation period increased. Sugar monomers (ribose, sucrose, xylose, rhamnose, lactose, maltose, glucose, arabinose and fructose) and polyhydric alcohol (glycerol, erythritol, arabitol, sorbitol, xylitol, galactitol, ribitol, maltitol and mannitol) with varying concentrations were obtained. The total sugar monomer concentrations obtained from pineapple peel, banana peel and orange peel media were 1612.25, 1534.79 and 1475.56 mg/100 g with corresponding polyhydric alcohol concentrations of 286.42, 250.71 and 247.94 mg/100 g respectively.

Conclusion: Based on the sugar monomers and polyhydric alcohol profile obtained in the research, Saccharomyces cerevisiae MP2 was able to overcome the challenging biological processes such as; delignification in order to release free cellulose and hemicellulose from the lignocellulosic material, depolymerization of the carbohydrate polymers from the cellulose and hemicellulose to generate free sugars, and fermentation of mixed hexose and pentose sugars to finally produce polyhydric alcohol.