Optimization of cellulase production using Bacillus thuringiensis strain TS-04-A halophilic bacterium.

Cellulose-hydrolyzing enzyme, cellulase, has a wide range of importance in many industries such as bioethanol, textiles, and food production. A novel isolate, Bacillus thuringiensis TS-04, from the salterns of Tuticorin, India, was identified through 16 S rDNA sequencing and selected for its superior cellulolytic activity (41.49 IU/mL) compared to other isolates. Optimization using Box-Behnken Design and Response Surface Methodology evaluated the effects of pH, incubation time, and inoculum percentage. The optimized conditions (pH 6.0, 72 h, 2.5% inoculum) yielded a maximum cellulase activity of 50.29 IU/mL, a 1.21-fold increase demonstrating model accuracy (R² = 0.9061) and significance (p < 0.05). The crude cellulolytic enzyme preparation exhibited thermal stability at 37 °C and retained high activity in the presence of 1 M NaCl, confirming its halo-stability. The crude cellulolytic enzyme preparation significantly clarified mixed fruit juice and improved stain removal in detergent formulations. These properties distinguish TS-04 from other Bacillus spp., which typically lack combined high-salt tolerance, high productivity, and a broad multifunctional application range. This study establishes B. thuringiensis TS-04 as a promising candidate for industrial enzyme production under extreme conditions, supporting its potential integration into the food and detergent sectors. Future work will focus on enzyme purification and the scale-up of bioprocesses.