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.

Production Optimization and Biochemical Characterization of Cellulase from Geobacillus sp. KP43 Isolated from Hot Spring Water of Nepal

“…Regarding substrates, many studies frequently use raw (ligno-)cellulosic substrates as C-source instead of synthetic substrates, which can be preferable in the sense that these raw substrates are more representative of the inherent complexity of natural lignocellulosic materials. For instance, five species of Bacillus and Pseudomonas stutzeri showed maximum cellulase production using eucalyptus leaves as C-source among others such as corncob, sugarcane bagasse, rice husk, wheat straw, and seed pod of Bombax ceiba [ 60 ]. Similarly, the order of enzyme production using Bacillus subtilis strain with various substrates was sugarcane bagasse>wheat straw>rice husk, wheat bran>soybean meal>corncobs [ 61 ].…”

The Succession of the Cellulolytic Microbial Community from the Soil during Oat Straw Decomposition

“…In this cluster, major representatives also belonged to Bacteroidota (Ohtaekwangia and Microscillaceae). Many representatives of Acidobacteriota (4), Actinobacteriota (Conexibacter, Galbitalea, Dactylosporangium, Iamia, and Solirubrobacter), Verrucomicrobiota (9), Myxococcota (9), Cyanobacteria (3), Chloroflexi (6), Bdellovibrionota (4), Spirochaeota (3), Planctomycetota (12), Crenarchaeota (4), Gemmatimonadota (1) and others appeared at this stage.…”

“…Soil from different environments can serve as a source of cellulolytic microorganisms. A number of studies focused on the isolation of single strains from various soil types [8][9][10][11][12], but this approach has several flaws. It was reported that cellulolytic bacteria may take up to a fifth part of the total soil community [13].…”

The Succession of the Cellulolytic Microbial Community from the Soil during Oat Straw Decomposition

“…Soil from different environments can serve as a source of cellulolytic microorganisms. A number of studies focused on the isolation of single strains from various soil types [ 14 , 15 , 16 , 17 , 18 ], but this approach has several flaws. It was reported that cellulolytic bacteria may take up to a fifth of the total soil community [ 19 ].…”