Production of Cellulases and Xylanase by Thermophilic and Alkaliphilic Bacterial Strains Isolated from Agricultural Wastes

Seven agricultural wastes named wheat bran (WB), rice straw (RS), wheat straw (WS), corn cob (CC), sugarcane bagasse (SCB), potato peal (PP) and banana peal (BP) were used for isolation of bacterial strains and as substrate for cellulases (CMCase, FPase and avicelase) and xylanase production. Five of the isolated strains were thermophilic and alkaliphilic. These bacterial isolates were tested to determine their abilities to produce cellulases and xylanase on the different agricultural wastes. The results revealed that isolate MAM-38 produced highest CMCase and avicelase (360 and 354 U/ml) on WB, while MAM-29 produced the highest FPase, xylanase and protein (54 and 294 U/ml and 894 μg/ml) respectively on the substrate. Bacterial isolate MAM-38 produced the highest CMCase, FPase, xylanase and extracellular protein (248, 38, 227 U/ml and 850 μg/ml), respectively on RS, while the highest avicelase produced (27 U/ml) was by MAM-29 on RS also. Isolate MAM-38 produced the highest CMCase (292, 561, 99 and 653 U/ml) on CC, SCB, PP and BP respectively. Isolate MAM-29 produced the highest FPase and avicelase (45 and 14 U/ml) on CC. The highest xylanase (503 U/ml) was produced by MAM-51 on SCB. So, the most potent isolates MAM-29 and MAM-38 were selected to determine their dose response curve. Gamma radiation (15 kGy) reduced the viable count of MAM-29 by 5.7 log cycles while reduced 4.7 log cycles for MAM-38. This means that MAM-38 was more resistant to gamma radiation than MAM-29.