(582g) Proteome Analysis of Secretome From Thermophilic Lignocellulose Degrading Microbe Geobacillus Sp. WSUCF1
Second-generation feedstock, especially inedible lignocellulosic biomass is a potential source for sustainable biofuels production. Several microorganisms such as bacteria and fungi have been reported to produce cellulases and xylanases for effective breakdown of lignocellulosic biomass. It is important to identify novel enzyme from diverse microbes that can effectively hydrolyze biomass, improve sugar yields and reduce the processing cost. In this regard, Geobacillus sp. WSUCFI was cultivated on different substrates, namely xylan, avicel, untreated corn stover, Ammonia Fiber Expansion (AFEXTM) pretreated corn stover and Extractive Ammonia (EA) pretreated corn stover. Spectral counting method was used to determine the composition of secretome and relative abundance of cellulolytic and hemicellulolytic enzymes produced by the microbe. Our results showed that protein profiles in the secretome vary with different substrates and pretreatment conditions due to complexity of the structures and composition. Secretomes with high yields of enzymes were observed when Avicel and AFEX corn stover were used as substrates. These secreted enzymes were then selected to carry out enzymatic hydrolysis of lignocellulosic biomass. Different combinations of crude secreted enzymes were used and compared with the conversions obtained from commercial fungal enzymes mixtures. Purified commercial enzymes such as CBH I and CBH II were also doped to study the enzyme synergy. Hydrolysis experiments were carried out using enzyme loadings of 15 and 60 mg/g glucan at 55ºC for 24 hours. Promising results were obtained for glucan and xylan conversion using enzyme obtained from Geobacillus Sp. WSUCFI and found to be comparable to sugar conversions when commercial enzymes were used.