Statistical Optimization of Cellulase Production by Thermomyces dupontii

Amylase and Cellulase Production from Newly Isolated Bacillus subtilis Using Acid Treated Potato Peel Waste

Species belonging to the genus Bacillus produce many advantageous extracellular enzymes that have tremendous applications on a commercial scale for the textile, detergent, feed, food, and beverage industries. This study aimed to isolate potent thermo-tolerant amylolytic and cellulolytic bacterium from the local environment. Using the Box-Behnken design of response surface methodology, we further optimized the amylase and cellulase activity. The isolate was identified by 16S rRNA gene sequencing as Bacillus subtilis QY4. This study utilized potato peel waste (PPW) as the biomaterial, which is excessively being dumped in an open environment. Nutritional status of the dried PPW was determined by proximate analysis. All experimental runs were carried out in 250 mL Erlenmeyer flasks containing acid treated PPW as a substrate by the thermos-tolerant Bacillus subtilis QY4 incubated at 37 °C for 72 h of submerged fermentation. Results revealed that the dilute H2SO4 assisted autoclaved treatment favored more amylase production (0.601 IU/mL/min) compared to the acid treatment whereas high cellulase production (1.269 IU/mL/min) was observed in the dilute acid treatment and was found to be very effective compared to the acid assisted autoclaved treatment. The p-value, F-value, and coefficient of determination proved the significance of the model. These results suggest that PPW could be sustainably used to produce enzymes, which offer tremendous applications in various industrial arrays, particularly in biofuel production.

Optimization of Cellulase Production by Cohnella xylanilytica RU-14 Using Statistical Methods

In this study, the cellulase activity by bacterial strain Cohnella xylanilytica RU-14 was enhanced by optimizing the medium components using statistical methods of Plackett-Burman design (PBD) and response surface methodology-central composite design (RSM-CCD). The cellulase assay was performed using NS enzyme assay method for reducing sugars. By PBD, the most significant factors (CMC, pH, and yeast extract) in an enzyme production medium that influence cellulase production by RU-14 were identified. These identified significant variables were further optimized using RSM by CCD. It was found that under optimized conditions of the medium components, the cellulase activity increased three times up to 14.5 U/mL as compared to un-optimized conditions (5.2 U/mL) of the enzyme production medium. The optimized levels of the significant factors determined by the CCD were found to be CMC, 2.3% w/v, and yeast extract, 0.75% w/v, at pH 7.5. The most adequate temperature for cellulase production by the bacterial strain was found to be 37 °C using the one-factor-at-a-time method. Thus, statistical methods to optimize medium conditions to enhance cellulase production by Cohnella xylanilytica RU-14 were found successful.

Thermostable cellulose saccharifying microbial enzymes: Characteristics, recent advances and biotechnological applications

Cellulases play a promising role in the bioconversion of renewable lignocellulosic biomass into fermentable sugars which are subsequently fermented to biofuels and other value-added chemicals. Besides biofuel industries, they are also in huge demand in textile, detergent, and paper and pulp industries. Low titres of cellulase production and processing are the main issues that contribute to high enzyme cost. The success of ethanol-based biorefinery depends on high production titres and the catalytic efficiency of cellulases functional at elevated temperatures with acid/alkali tolerance and the low cost. In view of their wider application in various industrial processes, stable cellulases that are active at elevated temperatures in the acidic-alkaline pH ranges, and organic solvents and salt tolerance would be useful. This review provides a recent update on the advances made in thermostable cellulases. Developments in their sources, characteristics and mechanisms are updated. Various methods such as rational design, directed evolution, synthetic & system biology and immobilization techniques adopted in evolving cellulases with ameliorated thermostability and characteristics are also discussed. The wide range of applications of thermostable cellulases in various industrial sectors is described.