Characterization of an alkaline active – thiol forming extracellular serine keratinase by the newly isolated Bacillus pumilus

Abstract

Aims: The aim of the study was to optimize microbial degradation of keratinous waste and to characterize the alkaline active keratinase showing its biotechnological importance. Method and Results: An extracellular keratinase enzyme was purified from the culture medium of a bacterial isolate and the conditions were optimized. The molecular weight of DEAE‐Sepharose‐purified keratinase was determined by SDS‐PAGE. Instrumental analyses were investigated to study the mechanism of bovine hair hydrolysis. Isolate was identified as Bacillus pumilus based on phenotypic characteristics and 16S rDNA sequence. The optimized condition for its growth was pH 8 and 35°C. The molecular weight of the keratinase was estimated as 65 kDa. Activity inhibition by phenyl methyl sulphonyl fluoride confirmed keratinase as serine protease type. Instrumental analysis revealed the sulphitolysis and proteolysis involved mechanism in bovine hair hydrolysis. Conclusion: This study indicates that the isolated keratinase is an alkaline active serine protease with a high degree of activity towards bovine hair. Significance and Impact of the Study: This study examines a serine protease with high keratinolytic activity and degradation mechanism for bovine hair. The keratinolytic activity of the isolated strain and its reaction mechanism on bovine hair could show biotechnological potential in the leather industry.

Production and properties of keratinolytic proteases from three novel Gram-negative feather-degrading bacteria isolated from Brazilian soils

“…The breakdown of disulfide bonds leads to the release of thiol groups and, thus, the concentration of thiol groups tends to increase during cultivation (Riffel et al 2003b;Kumar et al 2008), which was not clearly observed in this work. A. hydrophila K12 had a peak of 5.6 lg ml -1 after 168 h, C. indologenes A22 reached 5.0 lg ml -1 in 28 h, and the isolate S. marcescens P3 produced 3.5 lg ml -1 in 120 h of cultivation, all strains showing a high variability of thiol formation.…”

Biosynthesis and Control of Keratinase in Recalcitrant Feather-Degrading Bacillus megaterium F7-1

“…Since keratin has a very rigid structure through the formation of cystine disulfide bridges, feather degradation is likely to require reduction of the disulfide bonds. In other words, free SH group formation indicates the presence of disulfide reductase activity (Kumar et al, 2008;Sangali and Brandelli, 2000). Thus, our results suggest that B. megaterium F7-1 possesses disulfide reductase activity along with keratinase activity.…”

Wool-degrading Bacillus isolates: extracellular protease production for microbial processing of fabrics

“…Many efforts have been made to optimize protein overproduction and secretion by this genus, and several patents have resulted (Nijland and Kuipers 2008). Among potential substrates for proteases, keratin-rich products and by-products from different industries can be efficiently hydrolyzed by keratinolytic enzymes (Kumar et al 2008;Macedo et al 2005;Manczinger et al 2003) and the production of such enzymes is generally induced by keratinous substrates (Gupta and Ramnani 2006). In this work, we report the isolation of wool-degrading Bacillus strains, and the partial characterization of the extracellular proteases produced in a keratinous recalcitrant substrate (wool-fabric).…”