Plant biomass is efficiency decomposed by a great number of different microbial enzymes. The enzyme systems in cellulolytic bacteria have been genetically improved via plasmid transfer and genome shortening. In this study six conjugations were done between six parental strains carrying the opposite genetic markers from which 18 transconjugants were evaluated for biodegradation of cellulose. Three strains of Rhizobium leguminosarum bv. trifolii were used as recipients against Bt and Serratia strains expressing cellulose activity as donors. The wild type strains of Bacillus thuringiensis and Rhizobium encoded significant cellulose biodegradation after genome shortening. In addition, all transconjugants resulted from the mating between Bt₁ and Rh₁₁ expressed significant cellulase activities after curing. In constrant, all transconjugants results from the mating between Bt₂ x Rh₆ and Bt₂ x Rh₁₁ appeared insignificant differences in cellulase activity before and after curing. Meanwhile, the parental strains Rh₆ and Rh₁₁ expressed significant cellulase activity after curing. Furthermore, all transconjugants resulted from the mating between Sm x Rh₆ and Sm x Rh₁₅ encoded significant cellulase activity after curing.  This work provides efficiently encoded cellulases in genome shortening mutants than in the wild type. The enzymes encoded in this study represented that cellulase expressing genes were located on the bacterial chromosome and plasmids. Though, plant infection of legumes was affected by Rhizobia cellulases which considered as important determinant in nodulation process.