An alkali-thermotolerant extracellular protease from a newly isolated Streptomyces sp. DP2

Abstract

Of six alkalitolerant, extracellular protease producing bacterial strains isolated, DP2 displayed maximum activity. This organism was designated as Streptomyces sp. DP2 and identified as Streptomyces ambofaciens. Maximum protease yield was observed after 48hours of submerged fermentation using various carbon and nitrogen sources. Fructose was found to be the best substrate for protease production, followed by maltose, lactose and wheat bran. Mustard cake is reported for the first time as the most ideal nitrogen source although soybean meal also gave comparable yield. The protease produced by Streptomyces sp. DP2 exhibited extensive activity over a broad pH range (4-12) with maximum activity at pH 8, and was active over a broad range of elevated temperatures (50-100°C), and possessed thermostability at 60-90°C for up to 1 hour. Enzyme activity was reduced by EDTA (25%), SDS (16%), and PMSF (6%). This novel alkaline protease has both alkali- and thermostability that may have industrial significance.

Optimization of fibrinolytic protease production from Bacillus subtilis I-2 using agro-residues

“…Substrate cost substantially influences the economy of bulk production of industrial enzymes. Agricultural residues, available in abundance in India, may serve as lowcost substrates for economical production of enzymes including proteases (Bajaj and Sharma 2011;Bajaj et al 2012;Bajaj et al 2013). Extracellular protease production by the microorganisms is strongly influenced by the cultural and environmental variables (Bajaj and Sharma 2011).…”

“…Agricultural residues, available in abundance in India, may serve as lowcost substrates for economical production of enzymes including proteases (Bajaj and Sharma 2011;Bajaj et al 2012;Bajaj et al 2013). Extracellular protease production by the microorganisms is strongly influenced by the cultural and environmental variables (Bajaj and Sharma 2011). Generally, the moderately complex substrates serve as conditioned carbon sources for microbial enzyme production realizing the slow release of carbon and obviating the catabolite repression (Bajaj and Singh 2010).…”

“…(Wang et al 2009;Agrebi et al 2010;Bajaj et al 2013). The type and availability of nitrogenous precursors in the medium influence the production of extracellular enzymes (Bajaj and Sharma 2011). Besides, nitrogen source can significantly affect the medium pH during the course of fermentation, which in turn may influence enzyme activity and stability.…”

“…Screening of the bacterial isolates was accomplished at primary and secondary levels. In the primary screening, each isolate was examined for proteolytic activity on skimmed milk agar (SKMA) plates containing skimmed milk powder (0.5%, w/v) and agar (2%, w/v) by spot and well assay (Bajaj and Sharma 2011). Bacterial isolates, which exhibited proteolytic activity, were subjected to secondary screening on fibrin plate to ascertain their fibrinolytic activity.…”

Optimization of the xylanase production with the newly isolated Bacillus aerophilus KGJ2

“…The molecular characterization was done by using 16S rRNA sequencing technique [15]. The genomic DNA was extracted from the given organism using standard procedures [16].…”