In this study, a novel thermophilic strain was isolated from soil and used for cellulase production in submerged fermentation using potato peel as sole carbon source. The bacterium was identified by 16S rRNA gene sequencing technology. Central composite design was applied for enhanced production using substrate concentration, inoculum size, yeast extract and pH as dependent variables. Highest enzyme titer of 3.50 ± 0.11 IU/ml was obtained at 2% substrate concentration, 2% inoculum size, 1% yeast extract, pH 5.0, incubation temperature of 50 °C for 24 h of fermentation period. The crude enzyme was characterized having optimum pH and temperature of 7.0 and 50 °C, respectively. The efficiency of enzyme was checked by enzymatic hydrolysis of acid/alkali treated pine needles which revealed that 54.389% saccharification was observed in acid treated pine needles. These results indicated that the cellulase produced by the Bacillus subtilis K-18 (KX881940) could be effectively used for industrial processes particularly for bioethanol production.

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.

Potato peel waste (PPW) was utilized as a bio-template for the production of valuable compounds such as reducing sugars (RS), total sugar (TS) and total phenolic compounds (TPC). Two methods of alkali treatments, i.e., chemical (NaOH) and thermochemical (NaOH assisted with autoclaving) processes, were employed for the deconstruction of PPW. Response surface methodology (RSM) was used to study the effects of alkali concentration (0.6–1.0 w/v), substrate concentration (5–15 g) and time (4–8 h) on the extraction of RS, TS and TP from PPW. The application of alkali plus steam treatment in Box-Behnken design (BBD) with three levels yielded the optimum releases of RS, TS and TP as 7.163, 28.971 and 4.064 mg/mL, respectively, corresponding to 10% substrate loading, in 0.6% NaOH for 8 h. However, the alkali treatment reported optimum extractions of RS, TS and TP as 4.061, 17.432 and 2.993 mg/mL, respectively. The thermochemical pretreatment was proven a beneficial process as it led to higher productions of TP. FTIR and SEM were used to analyze the deterioration levels of the substrate. The present work was used to explore the sustainable management of PPW, which is a highly neglected substrate bioresource but is excessively dumped in open environment, raising environmental concerns. The cost-effective methods for the breakdown of PPW starch into fermentable sugars might be utilized to extract valuable compounds.

The present work focuses on the utilization of potato peel waste for the production of bioethanol. In the present study, extensive screening was undertaken to isolate amylolytic and cellulolytic microbes using starchy biomass. After confirming the chemical composition of potato peel waste (PPW), several trials were performed to enhance the amylase and cellulase production from Bacillus subtilis to hydrolyze the PPW in submerged fermentation. Optimization of physical parameters was performed using both commercial and indigenous media from enzymatically hydrolyzed PPW. Different routes of various combinations were designed to enhance bioethanol production. The maximum ethanol titer of 0.50% and 0.41% was recorded in Route B and A, i.e., separate saccharification and ethanol fermentation and consolidated fermentation. Simultaneous saccharification and fermentation (SSF) also measured a good ethanol yield of 0.46%. The fermented residual cake was checked for nutritional components and showed a high content of protein and amino acids because of the addition of unicellular yeasts. This cake can be utilized as an animal feed supplement.