Optimization of Alkali Treatment for Production of Fermentable Sugars and Phenolic Compounds from Potato Peel Waste Using Topographical Characterization and FTIR Spectroscopy.

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.

Carboxymethyl cellulase production optimization from newly isolated thermophilic Bacillus subtilis K-18 for saccharification using response surface methodology.

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.