Microbial proteases: A next generation green catalyst for industrial, environmental and biomedical sustainability

Proteases are among the most important classes of hydrolytic enzymes and occupy a key position due to their applicability in both physiological and commercial fields. They are essential constituents of all forms of life, including plants, animals, and microorganisms. However, microorganisms represent an attractive source for protease secretion due to their high productivity in a relatively short time and limited space requirements for cultivation, amongst others. Microbial proteases are produced by submerged or solid-state fermentation process during post-exponential or stationary growth phase. The production of these biocatalysts by microbes is influenced by nutritional and physicochemical parameters. Downstream recovery of high-value enzyme products from culture supernatant using suitable techniques is imperative prior to further use of the biocatalysts. Immobilization of these enzymes in appropriate matrices permits reusability, reclamation, enhanced stability and cost-effectiveness of the biocatalysts. The catalytic properties of microbial proteases help in the discovery of enzymes with high activity and stability, over extreme temperatures and pH for utilization in large-scale bioprocesses. This review provides insights into microbial proteases taking cognizance of the bioprocess parameters influencing microbial proteases production coupled with methods employed for protease purification as well as the immobilization and biochemical properties of the biocatalysts for potential biotechnological applications

Optimization of culture conditions for enhanced lipase production by an indigenous Bacillus aryabhattai SE3-PB using response surface methodology

Lipases are enzymes that hydrolyze fats into fatty acids and glycerol at the water–lipid interface and are also involved in a variety of bioconversion reactions in non-aqueous and micro-aqueous environments. In this study, we optimized the culture conditions for extracellular lipase production by an indigenous lipase-producing bacterial strain isolated from lipid-rich wastewater, using response surface methodology. The studied isolate was identified as Bacillus aryabhattai SE3-PB by polymerase chain reaction and analysis of 16S rDNA. Sunflower oil was found to induce maximum lipase production. Face centered central composite design revealed that temperature (40 °C), pH (7.6), inoculum volume (2.8%, v/v), agitation (193 rpm) and inducer oil concentration (2%, v/v) significantly influenced lipase production at the respective optimum conditions. The coincidence of observed lipase production (264.02 ± 1.94 U/mL) with predicted lipase yield (265.82 U/mL) coupled with a high correlation coefficient (R2 = 0.9919, P < 0.01) confirmed the validity of the model. A 7.2-fold increase in lipase production was obtained in the optimized medium compared to the basal medium. These findings provide the first report on lipase production and optimization by B. aryabhattai SE3-PB and suggest a rational choice of optimum processing conditions for commercial lipase production by B. aryabhattai SE3-PB

Biocatalytic Profiling of Free and Immobilized Partially Purified Alkaline Protease from an Autochthonous <i>Bacillus aryabhattai</i> Ab15-ES

Partially purified alkaline protease produced by an indigenous bacterial strain, Bacillus aryabhattai Ab15-ES, was insolubilized in alginate beads using an entrapment technique. Maximum entrapped enzyme activities of 68.76% and 71.06% were recorded at optimum conditions of 2% (w/v) sodium alginate and 0.3 M calcium chloride. Biochemical profiling of free and immobilized proteases was investigated by determining their activity and stability as well as kinetic properties. Both enzyme preparations exhibited maximum activity at the optimum pH and temperature of 8.0 and 50 °C, respectively. However, in comparison to the free enzyme, the immobilized protease showed improved pH stability at 8.0–9.0 and thermal stability at 40–50 °C. In addition, the entrapped protease exhibited a higher Vmax and increased affinity to the substrate (1.65-fold) than the soluble enzyme. The immobilized protease was found to be more stable than the free enzyme, retaining 80.88% and 38.37% of its initial activity when stored at 4 °C and 25 °C, respectively, for 30 d. After repeated use seven times, the protease entrapped in alginate beads maintained 32.93% of its original activity. These findings suggest the efficacy and sustainability of the developed immobilized catalytic system for various biotechnological applications