From the hindgut contents of Holotrichia parallela larvae,207 aerobic and facultatively anaerobic cellulolytic bacterial isolates were obtained.These bacterial isolates were assigned to 21 genotypes by amplified ribosomal DNA restriction analysis(ARDRA).A partial 16 S rDNA sequence analysis and standard biochemical and physiological tests were used for the assignment of the 21 representative isolates.Our results show that the cellulolytic bacterial community is dominated by the Proteobacteria(70.05%),followed by the Actinobacteria(24.15%),the Firmicutes(4.35%),and the Bacteroidetes(1.45%).And among the cellulolytic bacteria,some isolates,Siphonobacter aquaeclarae,Cellulosimicrobium funkei,Citrobacter freundii,Pseudomonas nitroreducens,and so on,are reported to be cellulolytic for the first time in this study.Among these isolates,a novel bacterium,designated Pseudomonas sp.HP207,with the highest endoglucanase productivity was selected for further study.The production of the endoglucanase was optimized by varying various physical culture conditions using a submerged fermentation method.Under the optimized fermentation conditions,the maximum endoglucanase activity of 1.432 U mL~(-1) in bacterial cultures was obtained,higher than those of the most widely studied bacteria and fungi,which are the attractive candidates for the commercial producer of cellulase.And the crude endoglucanase enzyme was also highly thermostable;approximately 55% of the original activity was maintained after pretreatment at 70°C for 1 h.Thus,from the present study,the bacterium can be added up to the database of cellulolytic bacteria,the scarab gut is an attractive source for the study of novel cellulolytic microorganisms and enzymes useful for cellulose degradation. From the hindgut contents of Holotrichia parallela larvae, 207 aerobic and facultatively anaerobic cellulolytic bacterial isolates were obtained. The bacterial isolates were assigned to 21 genotypes by amplified ribosomal DNA restriction analysis (ARDRA). A partial 16 S rDNA sequence analysis and standard biochemical and physiological tests were used for the assignment of the 21 representative isolates. Here results show that the cellulolytic bacterial community is dominated by the Proteobacteria (70.05%), followed by the Actinobacteria (24.15%), the Firmicutes (4.35%), and the Bacteroidetes 1.45%). And among the cellulolytic bacteria, some isolates, Siphonobacter aquaeclarae, Cellulosimicrobium funkei, Citrobacter freundii, Pseudomonas nitroreducens, and so on, are reported to be cellulolytic for the first time in this study. Am these isolates, a novel bacterium, designated Pseudomonas sp. HP207, with the highest endoglucanase productivity was selected for further study. The production of the endoglucanas The was optimized by varying various physical culture conditions using a submerged fermentation method. Under the optimized fermentation conditions, the maximum endoglucanase activity of 1.432 U mL ~ (-1) in bacterial cultures was obtained, higher than those of the most widely studied bacteria and fungi, which are the attractive candidates for the commercial producer of cellulase. And the crude endoglucanase enzyme also also highly thermostable; approximately 55% of the original activity was maintained after pretreatment at 70 ° C for 1 h. Thus, from the present study, the bacterium can be added up to the database of cellulolytic bacteria, the scarab gut is an attractive source for the study of novel cellulolytic microorganisms and enzymes useful for cellulose degradation.