Isolation, screening, and optimization of CMCase production from Bacillus pumilus A5 isolated from the fecal sample of Bos indicus

Bacterial cellulase plays a vital role in industries, such as bioethanol, textiles, paper and pulp, etc. Although numerous cellulolytic bacteria have already been isolated from diverse ecological niches, for the exploration of more potential bacteria, a fecal sample of Bos indicus was collected from Godhra, Gujarat, India. The serially diluted fecal sample was cultured on Bushnell Haas carboxymethyl cellulase (CMC) agar using the spreading technique, resulting in the isolation of five morphologically different bacterial colonies. Among these, isolate A5 was selected for further characterization, as it showed the best result in both qualitative and quantitative tests. The comprehensive investigation, which included colony morphology, biochemical profiling, and 16S Ribosomal RNA gene sequencing, identified isolate A5 as Bacillus pumilus. Optimal cellulase synthesis occurred at neutral pH (7.0) and 40°C after 72 h of incubation in a 2% (w/v) CMC-enriched production medium. Crude extract of this strain possessed activity against multiple substrates, including CMC, pectin, starch, 4-nitrophenyl β-D-glucopyranoside, and xylan, which highlights its potential for many industries, including bioethanol, textile, paper and pulp, etc.