Genomic and bioreactor evaluation of newly isolated cellulase-producing bacteria

Cellulose is a renewable resource with broad biotechnological potential, and its hydrolysis by cellulases underpins applications such as biofuel production and biowaste valorization. This study combined isolation, screening, molecular identification, enzyme assays, genome sequencing, and bioreactor evaluation to characterize novel cellulase-producing bacteria. Preliminary screening identified and selected bacterial isolates by hydrolysis halo formation, with strains showing halos ≥ 20 mm selected for further quantitative assays. Streptomyces olivaceus C1_7A, Bacillus thuringiensis FBB7BB, and Bacillus licheniformis strains AT081C and AT082C showed the highest endoglucanase activities (from 0.11 to 0.26 U mL−1). Further testing on Arundo donax and Avicel led to the selection of B. thuringiensis FBB7BB and S. olivaceus C1_7A as the most promising strains for biotechnological application. Whole genome sequencing confirmed the presence of genes involved in polysaccharide degradation. Finally, lab-scale fermentation trials using 1–2% CMC showed that B. thuringiensis FBB7BB reached a maximum endo-1,4-β-glucanase activity of 0.30 ± 0.04 U mL−1 after 8 h at 37 °C, whereas S. olivaceus C1_7A achieved 0.36 ± 0.03 U mL−1 after 216 h at 30 °C.