Two Bacillus Species Isolated from Rotting Wood Samples are Good Candidates for the Production of Bioethanol using Agave Biomass

Abstract

The biorefining of crop and plant organic matter represents a promising route to produce renewable fuels and bioproducts. The high contents of cellulose and hemicellulose make Agave americana an ideal candidate to produce value-added products. In this study, two different cellulase producing bacteria, isolated from rotting wood samples, were incubated and cultivated to examine their ability to decompose agave and produce ethanol. The results showed the transparent zones called halos on the plates containing Agave as the sole carbon source after iodine staining for these two isolates and positive control Cellulomonas xylanilytica; while, no halo was observed for negative control: Escherichia coli BL21. The Bacillus species K1 and A0 displayed hydrolysis ability greater than that of positive control based on halo diameter. Moreover, the quantitative ability to decompose agave was studied for the same two bacterial strains using minimal salt media containing 5% agave biomass. Dinitrosalicylic acid (DNS) method was used to detect cellulase and reducing sugars. Ethanol was detected by using micro-dichromate method. The results showed that strain K1 produced 0.435 g ethanol/g Agave biomass and the isolate A0 produced 0.397 g/g ethanol on the 4th day of incubation.