Résumé:
Facing the crucial issue of high production costs for cellulase, numerous studies have
focused on improving the efficiency of cellulase production by potential microorganisms
capable of secreting this enzyme using low-cost agricultural wastes as inducer substrates,
extremophilic cellulases, in particular, are crucial in the biorefinery process because they can
maintain activity under harsh environmental conditions. This study aims to investigate the
ability to produce a thermotolerant and halotolerant cellulase from untreated olive mill wastes
using the potential carboxymethylcellulose-hydrolyzing bacterial strain H1 that was newly
isolated from an Algerian saline soil and identified as Bacillus velezensis. The enzyme
produced under optimized conditions, was succefully purified and its molecular mass was
estimated to be 26 kDa by SDS-PAGE. Identification by LC-MS analysis and substrate
specificity revealed that the studied enzyme is an endo-1,4-β-glucanase. Physico-chemical
characterization showed that optimal enzymatic activity was at pH 6.0-6.5 and at 60-65 °C. It
was fairly thermotolerant, retaining 76.9% of the activity at 70 °C, and halotolerant, retaining
70% of its activity in the presence of 4 M NaCl. Kinetic analysis and the ability of the enzyme
to release cello-oligosaccharides were also investigated
