Statistical optimisation of protease production using a freshwater bacterium Chryseobacterium cucumeris SARJS-2 for multiple industrial applications.

Feathers, rich in keratin, are usually the unused by-products of poultry industries. In addition, the cast-off X-ray films serve as secondary sources of silver, and the traditional method of silver extraction from this source is costly and not eco-friendly. Therefore, the current study focuses on protease production using a freshwater bacterium Chryseobacterium cucumeris SARJS-2, aiming to convert these wastes into useful products. The protease production was optimized by one-factor-at-a-time (OFAT), followed by Plackett Burman design (PBD) and response surface methodology (RSM). The protease production got enhanced by more than two folds after the statistical optimisation. Upon partial purification, the enzyme activity increased by approximately three folds. The protease was active in the range of temperatures from 25 to 75 °C, but the optimum temperature was recorded as 35 °C. The protease exhibited detergent compatibility and organic solvent stability. The detergent compatibility suggests the protease could be a detergent additive. It was also found that the presence of Fe+2 enhanced protease activity. The protease was tested for stain removal, feather degradation and silver recovery applications. It was found that the protease could efficiently remove stains of blood and tomato sauce. In addition, the protease was found to be a successful candidate for feather degradation, thereby feather-hydrolysate production which has prominent roles as nature-friendly fertilizer and animal feed ingredient. The protease also degraded gelatin from the X-ray films to release the silver-halides for silver recovery. The results recommend that the SARJS-2 protease is a potential candidate for use in eco-friendly applications in various industrial sectors.

Statistical optimization and characterization of bacterial cellulose produced by isolated thermophilic Bacillus licheniformis strain ZBT2.

Bacterial cellulose (BC) is an excellent natural biopolymer with wide range of applications. The present study reports a potential BC producing thermophile, identified as Bacillus licheniformis strain ZBT2. The thermophile produced pellicle form of BC (3.0 g/l) under static conditions. Statistical optimization of BC was carried out by Plackett-Burman and central composite design. Results suggest that BC yield (9.2 g/l) was enhanced with 6.6-fold after optimization. BC-gelatin hydrogels composites were developed to assess various properties. The water retention capability and moisture content properties of BC and composites were promising and also exhibited negligible protein adsorption. The composites also demonstrated to be consistent during controlled drug delivery profiling. Furthermore, the composites also demonstrated antibacterial efficiency against Escherichia coli and Micrococcus luteus. The structural, morphological and thermal properties were assessed by analytical techniques such as, fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray analysis, thermogravimetric analysis and differential scanning calorimetry analysis. The study reflects the exploitation of a thermophile for development of BC which can be a preferred choice as a scaffold for tissue engineering and drug-delivery systems.