Identification of Natural Antimicrobial Extracts from Lignocellulosic Biomasses for contamination control in Bioethanol production from Organic Fraction of Municipal Solid Waste

Abstract

This project aims at developing alternate method for contamination control of lactic acid bacteria (LAB) during the bioethanol production from organic fraction of municipal solid waste (OFMSW), by using potential antimicrobial products from various natural plant sources in Abu Dhabi. The major challenge in bioethanol fermentation is overcoming the bacterial contamination particularly by LAB as it reduces the viability of yeast and hence ethanol yields. The current use of antibiotics for contamination control has given rise to development of antibiotic resistant bacterial strains, leading to environmental pollution as well as economic problem for bioethanol industries. Antimicrobial activity of water extracts and pretreated liquids from various native biomass like parts of date palm; parts of mangrove tree; and garden trimmings were analyzed to see if they could inhibit LAB but allowing the growth of the yeast, S.cereviasae, using plating techniques and inhibition zone study. Extracts or pretreated liquids which exhibits this property can be used as an alternative for the antibiotics in ethanol fermentation to inhibit lactic acid production. The pretreated liquids of the date palm rachis and that of the mangrove stem and leaf were the promising natural antimicrobial agents identified in this study. Detailed studies on the effect of inhibitors such as furfural and HMF on controlling the lactic acid contamination during fermentation of OFMSW was also carried out. Lactic acid production was observed even at higher inhibitor concentration of 4 g/l. This mechanism is attributed to the complex nature of OFMSW. Amylolytic strains of lactic acid bacteria were isolated from OFMSW. Economical evaluation of the biorefinery wherein MSW is converted to bioethanol has also been carried out using SuperPro Designer.

Date of Award	May 2015
Original language	American English
Supervisor	Mette H. Thomsen (Supervisor)