Termite gut microbiome being a rich source of potential lignocellulolytic bacterial strains

Abstract

A study was carried out to identify prospective cellulose degrading bacteria isolated from termite gut collected from various agriculture sites. Eight of the bacterial isolates displayed a very distinct zone of clearing on CMC (Carboxylmethyl cellulose) agar media after staining with 1% Congo red, indicating that they may have cellulose degrading ability. On a CMC agar plate, CRDB6 had the largest colony diameter (3.08 cm) as well as clear zone diameter (0.96 cm), however CRDB 1 has maximum cellulolytic activity (1.45 cm) followed by CRDB5 and CRDB6 (1.33 cm and 1.28 cm) respectively. CRDB3, CRDB4 and CRDB9 showed Gram negative reaction among crop residue degrading bacterial isolates, while the remainder showed Gram positive reaction. The morphological characteristics of the bacteria isolates, such as colony shape, elevation, margin, colour and opacity, differed. Isolates CRDB6 produced highest β-glucosidase activity (12.66 m L-1) followed by CRDB1 (12.20 mg m L-1) and CRDB5 (10.21 m L-1) in Luria broth culture. Indole acetic acid production (with tryptophan) was greater in CRDB1 (389.33 mg/ml), CRDB6 (356.9 m L-1) and CRDB3 (315.96 m L-1) while as P-solubilization potential was peaked in CRDB6 (2.41 m L-1) followed by CRDB4 (1.76 m L-1) and CRDB3. Overall, isolate CRDB6 exhibited the highest cellulolytic activity as compared to rest of the bacterial isolates. These results will help in preparing bacterial consortia for the management of crop residues.