Alkaline protease production from alkalophilic Bacillus sp. isolated from natural habitats

Abstract

Bacillus strains isolated under extreme alkaline conditions (Izmir, Turkey), were screened and identified for high alkaline protease activity. Strains with high protease yields were optimized with respect to inoculum concentration, temperature, agitation speed, initial medium pH and incubation time. Three Bacillus strains coded as I18, L18 and L21 showed high potential, for alkaline protease activity (160-222 U/ml) among 85 isolates. The specific growth rates were estimated from the growth curves as 0.49 h −1 for I18, as 0.6 and 0.7 h −1 for L18 and L21, respectively. The optimum temperatures were determined as 30 • C for strain I18 and 37 • C for the strains L18 and L21. Similarly, the optimum agitation speeds were 100 rpm for I18 and 180 rpm for L18 and L21. For all three strains, the optimum inoculation ratio and incubation time, were determined as 5% (v/v) and 96 h, respectively. The optimum initial media pH was found as pH 10 for strain L18 and L21. Bacillus sp. L21 with the highest specific protease activity (60 U/mg protein) and a broader pH range was chosen for further study. The biomass and product yield for this strain was determined as 0.023 g cell/g glucose and 0.021 U/g glucose, respectively. The crude enzyme of this strain was further characterized and was determined as a bleach stable, serine alkaline protease with an optimum temperature of 60 • C and a pH of 11, with a potential to be a candidate for the applications in the detergent industry.

Optimization of a growth medium using a statistical approach for the production of an alkaline protease from a newly isolated Bacillus sp. L21

“…It is highly important to discover new bacterial-strains that produce enzymes with novel properties that could be of industrial value [9]. Using response surface methodology, a low cost media formulation for alkaline protease production from the newly isolated Bacillus sp.…”

“…The phenotypic and genotypic study of this strain was completed and identified as a close homologue of Bacillus gibsonii and Bacillus pseudofirmus based on 16S-ITS rDNA RFPL analysis [8]. This organism showed higher proteolytic activity in the initial optimization study of the fermentation conditions as compared with the other two strains [9]. Therefore, taking this strain as a potential candidate for industrial use, a further detailed study on media optimization was proposed.…”

Concomitant production of protease and lipase by Bacillus licheniformis VSG1: production, purification and characterization

“…Proteases and lipases occur widely in microorganisms, plants and animals (15,21). Among the microbial sources, bacteria especially Bacillus sp have been exploited for production of proteases and lipases (6,17). There are many reports which have optimized the production of protease and lipase in separate media and very few reports on a mixed media.…”

Utilização de resíduos agroindustriais para a produção de proteases pelo termofílico Bacillus sp em fermentação submersa: otimização do meio de cultura usando a técnica de planejamento experimental

“…[1][2][3][4][5] Devido à promissora aplicabilidade das proteases e ao seu alto custo de obtenção, sua produção deve ser intensificada utilizandose para esse fim, meios de cultura de baixo custo, 6 levando em consideração que aproximadamente 30 a 40% do custo envolvido na sua produção está relacionado ao meio de cultura utilizado para o crescimento do micro-organismo. Nesse contexto, em escala industrial, exoenzimas como as proteases alcalinas são produzidas com meios de cultura complexos, contendo glicose e outros substratos de alto custo.…”