ISOLATION OF CELLULOLYTIC BACTERIA FROM SOIL AND VALORIZATION OF DIFFERENT LIGNOCELLULOSIC WASTES FOR CELLULASE PRODUCTION BY SUBMERGED FERMENTATION

Abstract

Cellulases are known to convert cellulose into monomeric or dimeric structures, hence playing an important role in bioethanol production, along with their applications in textile and paper industries. This study was directed towards the isolation and screening of cellulase producing bacteria from different soil samples on CMC (carboxymethyl cellulose) agar plates, followed by Gram’s iodine staining. Six strains showed clear zones of hydrolysis on CMC agar plates. Isolates were identified as Bacillus megaterium, Pseudomonas stutzeri, Bacillus aerius, Bacillus paralichniformis, Bacillus flexus, and Bacillus wiedmanni by 16S rRNA gene sequencing. These strains were cultivated by submerged fermentation for cellulase production using various lignocellulosic wastes, such as corn cob, rice husk, wheat straw, seed pods of Bombax ceiba and eucalyptus leaves. Results showed that Pseudomonas stutzeri is the best cellulase producer among these strains. It offered the highest cellulase activity of 170.9±4.1 (IU/mL/min) in media containing eucalyptus leaves after 24 h of incubation at 37 °C, followed by Bacillus paralichniformis, Bacillus wiedmanni, Bacillus flexus, Bacillus aerius and Bacillus megaterium. These bacterial strains and lignocellulosic wastes could be potentially used for industrial exploitation, particularly in biofuels and textiles.