Primary Structure of the Carbohydrate-Binding Modules in Various Cellulolytic, Thermophilic, Anaerobic, Ethanol-Producing Isolates

In the present study, the carbohydrate-binding module (CBM) coding sequences of the cellulosomes of 13 thermophilic,cellulolytic, anaerobic, ethanol-producing bacterial isolates having some variations in their growth and cellulose degradation capacities were amplified by PCR and then sequenced. The sequence analysis of the amplicons revealed that CBMs of 7 of the isolates including the isolate 7-9-1 with the highest capacity of cellulose degradation in solid medium have 100% identity in both nucleotide and aminoacid sequences to CipB of Clostridium thermocellum in the compared regions. On the other hand, CBM of the isolate 7-1-2, alsohaving a high cellulolytic activity, was found to differ for as much as 66 amino acid residues out of 100 (66%). The isolate 7-9-4with a relatively low cellulose-degrading capacity also displayed amino acid variation for this protein, but only for 4 out of 118 residues.