Rizobactérias amazônicas produtoras de celulases: potencial para produção enzimática individual e em consórcios

Abstract

The rhizosphere represents a highly complex and biologically active environment in which interactions between host plants and soil microorganisms play a central role in the decomposition of organic matter and the maintenance of soil fertility. Among these processes, cellulose degradation stands out for its ecological and biotechnological relevance, as this polymer constitutes the main structural component of plant biomass. In this context, the present study aimed to evaluate the cellulolytic potential of Amazonian rhizobacteria associated with Pueraria phaseoloides and Inga edulis, to investigate the influence of the host plant on the functional selection of these microorganisms, and to analyze the production of cellulolytic enzymes under monoculture and co-culture systems. Bacterial isolates were initially reactivated and subjected to qualitative screening on carboxymethylcellulose (CMC) medium, with the enzymatic index (EI) used as a selection criterion. A marked heterogeneity among isolates was observed, with a predominance of rhizobacteria exhibiting EI values equal to or greater than 2.0, indicative of high biotechnological potential. Comparative analysis between host plants revealed a significant influence of plant identity on cellulolytic potential, with isolates from P. phaseoloides showing higher mean EI values than those from I. edulis. Isolates with the highest enzymatic indices were morphologically characterized, subjected to Gram staining, and identified through molecular analysis. The results indicated a predominance of species belonging to the genus Bacillus, particularly Bacillus sp. 1, Bacillus sp. 2 and Bacillus sp. 3. Based on these criteria, selected strains were further evaluated for the production of e total cellulases (FPase), endoglucanases (CMCase), and β-glucosidases. Enzymatic assays demonstrated that, although individual cultures exhibited limited and unstable cellulase production, co-culture systems promoted substantial increases in both the intensity and stability of enzymatic activity. The triple co-culture composed of Bacillus sp. 1 (INPA R-583), Bacillus sp. 2 (INPA R-774) and Bacillus sp. 3 (INPA R-762) emerged as the most efficient arrangement, evidencing synergistic interactions and functional complementarity among bacterial strains. The strategic use of Bacillus-based bacterial consortia represents an effective approach to enhance and stabilize cellulolytic enzyme production, contributing to advances in the understanding of rhizosphere functional ecology and providing a foundation for the development of lignocellulosic biomass degradation processes.