Improved catalytic efficiency of a monomeric gamma-glutamyl transpeptidase from Bacillus licheniformis in presence of subtilisin

Newly isolated Bacillus sp. G51 from Patagonian wool produces an enzyme combination suitable for felt-resist treatments of organic wool

Bacteria from Patagonian Merino wool were isolated to assess their wool-keratinolytic activity and potential for felt-resist treatments. Strains from Bacillus, Exiguobacterium, Deinococcus, and Micrococcus produced wool-degrading enzymes. Bacillus sp. G51 showed the highest wool-keratinolytic activity. LC-MS/MS analysis revealed that G51 secreted two serine proteases belonging to the peptidase family S8 (MEROPS) and a metalloprotease associated with Bacillolysin, along with other enzymes (γ-glutamyltranspeptidase and dihydrolipoyl dehydrogenases) that could be involved in reduction of keratin disulfide bonds. Optimum pH and temperature of G51 proteolytic activity were 9 and 60 °C, respectively. More than 80% of activity was retained in H₂O₂, Triton X-100, Tween 20, Lipocol OXO650, Teridol B, and β-mercaptoethanol. Treatment of wool top with G51 enzyme extract caused a decrease in wool felting tendency without significant weight loss (<1.5%). Sparse work has so far been performed to investigate suitable keratinases for the organic wool sector. This eco-friendly treatment based on a new enzyme combination produced by a wild bacterium has potential for meeting the demands of organic wool processing which bans the use of hazardous chemicals and genetic engineering.

Proteomic analysis of enzyme production by Bacillus licheniformis using different feather wastes as the sole fermentation media

This study evaluates the use of different types of feathers as fermentation media for enzyme production. Bacillus licheniformis was grown on the feathers, which lead to total biodegradation due to bacterial enzymatic hydrolytic excretion. B. licheniformis excretes protease and lipase activity, with feather concentration being the main parameter controlling their generation. Using a proteomic approach, the proteins excreted during fermentation were identified, and the influence of the chemical composition of the feathers on protein secretion was tested. The identified proteins are hydrolytic enzymes such as keratinase, gamma-glutamyltranspeptidase, chitosanases, and glicosidases. The diversity of proteins is related to the chemical complexity of the feathers. Understanding the composition of a hydrolytic system, when B. licheniformis is cultured on different feathers, may assist in utilizing such a system for producing different hydrolytic enzymes. The data indicate that proteomics can be a valuable tool for describing the physiological state of B. licheniformis cell populations growing on different wastes.

γ-Glutamyltranspeptidases: sequence, structure, biochemical properties, and biotechnological applications

γ-Glutamyltranspeptidases (γ-GTs) are ubiquitous enzymes that catalyze the hydrolysis of γ-glutamyl bonds in glutathione and glutamine and the transfer of the released γ-glutamyl group to amino acids or short peptides. These enzymes are involved in glutathione metabolism and play critical roles in antioxidant defense, detoxification, and inflammation processes. Moreover, γ-GTs have been recently found to be involved in many physiological disorders, such as Parkinson's disease and diabetes. In this review, the main biochemical and structural properties of γ-GTs isolated from different sources, as well as their conformational stability and mechanism of catalysis, are described and examined with the aim of contributing to the discussion on their structure-function relationships. Possible applications of γ-glutamyltranspeptidases in different fields of biotechnology and medicine are also discussed.

Revisiting microbial keratinases: next generation proteases for sustainable biotechnology

Keratinases are special proteases which attack the highly recalcitrant keratin substrates. They stand apart from the conventional proteases due to their broad substrate specificity towards a variety of insoluble keratin rich substrates like feather, wool, nail, hair. Owing to this ability, keratinases find immense applications in various environmental and biotechnological sectors. The current boost in keratinase research has come up with the discovery of the ability of keratinases to address the challenging issue of prion decontamination. Here we present a comprehensive review on microbial keratinases giving an account of chronological progress of research along with the major milestones. Major focus has been on the key characteristics of keratinases, such as substrate specificity, keratin degradation mechanisms, molecular properties, and their role in prion decontamination along with other pharmaceutical applications. We conclude by critically evaluating the present state of the keratinases discussing their commercial status along with future research directions.