Industrially Important Enzymes and Microbial Lipids for Biodiesel Synthesis from Organic Municipal Solid Wastes

A. Azad, Islam K, Ahmed J, Iqbal A, Sohag MMH, RakibuzzamanSM, Rana MM, Hakim A, Hasan M and Hossain S

Author address: 

Shahjalal Univ. of Sci. and Technology, Sylhet, Bangladesh


Municipal solid wastes (MSW) in the open dumping of developing countries result in environmental pollution, public health hazards and climate change. Organic MSW (OMSW) can be converted to bioresources through production of industrially and commercially important products, and thus the environmental pollution and climate change caused by MSW may be mitigated. We have isolated and identified proteolytic and cellulolytic bateria and fungi from MSW and cowdung. Based on the 16S rDNA sequence, the bacterial isolates were Bacillus cereus, Serratia marcescens and Pseudomonas aeroginosa, and based on the 18S rDNA sequence, the fungal isolates were Aspergillus oryzae, A. fumigatus and A. Flavus. Significant level of protease and cellulase were produced from bacterial and fungal isolates, respectively by using OMSW as raw materials in the shake flask and bioreactor. Physicochemical parameters such as temperature, pH, aeration, agitation, substrate concentrations etc were optimized for protease and cellulase production in the bioreactor. Protease production was scaled-up 2.5-3.0 fold in the bioreactor with reduction in fermentation period. The SDS-PAGE showed that the estimated molecular mass of the partially purified protease from S. marcescens was ~38 kDa and that from P. aeroginosa was ~25 kDa. Partially purified protease from both sources was characterized and enzyme kinetics were determined. Genome-wide analysis revealed that the genomes of A. oryzae, A. fumigatus and A. Flavus had 22, 25 and 23 cellulase genes, respectively. Some homologous cellulase genes were isolated from the three fungus isolates. Physicochemical parameters for microbial lipids production from oliagenous yeast Lipomyces starkeyi for biodiesel synthesis by using OMSW were optimized. Amount of accumulated lipids of L. starkeyi grown in OMSW hydrolysate media under optimal conditions was ~45% (v/w) of dry biomass of the yeast cells. Gas chromatographic analysis revealed that the fatty acid composition of this microbial lipid is similar to that of vegetable oils. Our study indicates that OMSW might be a valuable alternative feedstock for production of microbial lipids and industrially important enzymes.

abstract No: 


Full conference title: 

ASM Microbe 2016
    • ASM microbe 1st (2016)