The Influence of Temperature and Nitrogen Source on Cellulolytic Potential of Microbiota Isolated from Natural Environment

Bacteria from the genus Bacillus are a rich source of commercial enzymes, including amylases, proteases, cellulases, glucose isomerase, and pullulanase. Cellulases account for 15% of the global market of industrial enzymes; thus, new microorganisms producing cellulases in a higher concentration and new ingredients, which can enhance the level of enzyme synthesis, are still needed. Many of cellulose-degrading microorganisms have been isolated so far and characterized in various regions of the world. In this study, we were looking for the bacteria isolated from the natural environment with the high cellulolytic potential, which could be used as components of a biopreparation to accelerate decomposition of postharvest leftovers in agriculture. The 214 bacterial strains were isolated from environmental samples rich in cellulose and their ability to synthesize cellulases were examined using the diffusion method. Six strains, which have the highest diameter of clearing zone both for biomass and supernatant, were selected for identification. Optimization of biosynthesis of the cellulose-degrading enzymes indicated that optimal temperature of this process fluctuated in the range of 21–42°C (depending on the strain and carbon source). The highest cellulolytic activity was observed for the isolates designed as 4/7 (identified as Bacillus subtilis) and 4/18 (identified as Bacillus licheniformis) in a temperature of 32°C. With the use of a desirability function methodology, the optimal medium composition to achieve a simple, cost-efficient process of cellulases production was developed for both strains. These experiments show that microorganisms isolated from natural environmental samples have unique properties and potential for commercial applications (e.g. for biopreparations production).