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Two cellulolytic thermophilic bacterial isolates CS-3-2 and CS-4-4 were isolated from decayed corn stalk by adding growth-supporting factors to the medium.According to the 16S rRNA gene sequencing results they belonged to the genus Clostridium with similarity of 98.87% and 98.86% to Clostridium stercorarium subsp.leptospartum ATCC 35414T and Clostridium cellulosi AS 1.1777T,respectively.They are complementing each other in lignocellulosedegradation.The endoglucanaseand exoglucanase activity of strain CS-4-4 is about 3-4 times of that of strain CS-3-2,while the β-glucosidase activity of strain CS-3-2 is 14 times higher.The xylanase activity of strain CS-3-2 is 9 times of that of strain CS-4-4 while the β-xylosidase activity of strain CS-4-4 is 25 times of that of strain CS-3-2.The enzyme activities in the spent cultures of a co-cultivation of the two strains with natural biomass as substrate were about 1.5-6 times ofthe pure cultures or a mixture of their enzyme products indicating synergism between the two strains.Liberative sugars and fermentation products of the co-cultivation sample were also superior to others.LC-MS analysis of protein band appearing in the native-zymogramsshowed that ORF3880 and ORF3883 from strain CS-4-4playedthe key role in the lignocellulose-degrading process.The two ORFs possessed similar characters except that ORF3880 was better in adhesion to insoluble substrates owing to its five CBM modules.