Optimization and validation of keratinase production by Bacillus aerius NSMk2 in a stirred tank reactor using response surface methodology

Abstract

Keratinase is a robust enzyme that is produced in the presence of keratin substrates. This enzyme has been recognized for its applications in waste management, leather and detergent industries. Our group has isolated a potential keratinase producing strain of Bacillus aerius NSMk2 from poultry dump soil, and its hide dehairing and stain removal applications have been studied. Considering commercial applicability of keratinase, the present study reports the keratinase production in a stirred tank reactor (5 l). Central composite rotatable design of response surface methodology (RSM) was employed to study the effect of most influencing process variables, i.e., aeration (0.5–1.5 vvm), agitation (150–350 rpm) and incubation period (24–48 h) on keratinase production. The quadratic model predicted 15 experimental runs, and the influence of independent variables and their interaction on keratinase production were interpreted using analysis of variance (ANOVA) and t-test statistics. Coefficient of determination (R2) value close to 1 and Fisher F-value of 3743.77 showed good fit of experimental data to second-order polynomial equation. A reasonable agreement between experimental and predicted values showed the accuracy of deduced model. Applying the desirability function, aeration rate of 1.0 vvm, agitation rate of 276.88 rpm and incubation period of 33.68 h supported maximum keratinase production (318.38 U/ml). Confirmatory experiments were performed to evaluate the accuracy of desirability function. Maximum keratinase activity of 318.11 U/ml close to predicted value (318.38 U/ml) validates the model. The present study provides useful guidelines for large-scale production of keratinase that can be used for various commercial applications. Article highlights Keratinase production was optimized in a stirred tank reactor by RSM. The influence of aeration, agitation and incubation period on keratinase production was studied. A significant increase in keratinase production was observed at 1.0 vvm aeration and 276.88 rpm agitation after 33.68 h.

Innovative Artificial-Intelligence- Based Approach for the Biodegradation of Feather Keratin by Bacillus paramycoides, and Cytotoxicity of the Resulting Amino Acids

“…Generally, keratin-degrading efficiency is well reported in several bacteria, especially Bacillus spp., that can thrive on the keratinous biomass as the sole source of nitrogen, and carbon, indicating the secretion of protein-and keratin-degrading enzymes (Nnolim et al, 2020;Bhari et al, 2021;Cavello et al, 2021;Li, 2021). Bacillus spp.…”

“…The species include B. subtilis, B. aerius, B. pumilus, B. cytotoxicus, B. cereus, and B. lichenifomis (Cavello et al, 2021;Li, 2021). The latter is the first commercial keratinase preparation source (Bhari et al, 2021). The current B. paramycoides ZW-5 is another new candidate in this respect.…”

Effect of pre-treatment of chicken feather on the degradation potential of Glutamicibacter arilaitensis

“…Keratinase production from G. arilaitensis has been proved that the bacterium has higher keratinolytic ability to degrade large biomass. Bhari et al (2021) studies, maximum protein (1.81mg ml ) and amino acids (1.54 mg ml ) were produced at pH 10.5 at 37°C after 72 hrs of incubation in 0.1 N NaOH pre-treated feather. Amuthavalli and Ravi (2023) reported that growth of G. arilaitensis and protein production was higher at alkaline pH 8 and 40°C.…”