Isolation of alkali-thermotolerant cellulolytic bacteria from spent mushroom substrate

Abstract

In this study, the isolation of new alkali-thermophilic bacteria with enhanced cellulase producing ability from the spent mushroom substrate was conducted. Repeated streaking was performed on the Microcrystalline-cellulose (MCC) to obtain a pure culture. Two thermophiles bacteria isolates were used for subsequent experiment. Morphological characteristic by gram staining and endospore staining also genetic identification of 16S rDNA was performed and the growth profile had been generated using Polymath Software. Filter paper assay (determination of enzyme activity), Bradford protein concentration were used in plotting the growth associated product curve. Based on the 16S rDNA sequencing results, the bacterium strains of Anoxybacillus geothermalis, incubated at 50˚C, pH 7 and Aeribacillus pallidus, incubated at 60˚C, pH 8 was successfully isolated. Both strains are gram-positive and endospore-forming bacteria. Based on the growth curve, the doubling time for Anoxybacillus geothermalis was calculated to be 49.5 minutes. Whereas, doubling time of Aeribacillus pallidus was 56.7 minutes. Both strains represent the growth assosiated product curve in which, when product formation is growth associated the specific rate of the product formation increases with specific growth rate and vice versa.