Keratinases from Streptomyces netropsis and Bacillus subtilis and Their Potential Use in the Chicken Feather Degrading

Abstract

Feathers are the most prevalent agricultural waste generated by chicken farms, polluting the environment and wasting protein resources as a result of the accumulation of large amounts of feathers. Therefore, keratinase-producing microorganisms represent a promising potential technique for the degradation of feather waste. Streptomyces netropsis A-ICA and Bacillus subtilis ALICA, previously isolated from the rhizosphere of desert plants (Larrea tridentata and Prosopis juliflora) respectively, were assessed for their feather-degradation ability. Keratinase activity was optimized using various parameters, including incubation time, pH, temperature, and feather concentration. The maximum keratinase activity of S. netropsis A-ICA and B. subtilis ALICA (113.6 ± 5.1 and 135.6 ± 4.1 U/mL) was obtained at the 5th and 3rd day of incubation with initial pH of 7.0 and 7.5 at 25 and 30 °C, and 1% (w/v) of chicken feather, respectively. Under the optimized conditions, the concentration of soluble protein in the feather hydrolysate reached 423.3 ± 25 and 565.3 ± 7.7 µg/mL, with feathers weight loss of 84 ± 2 and 86± 1.5% by S. netropsis A-ICA and B. subtilis ALICA, respectively. The highest disulphide bond reductase activity reached 10.7 ± 0.4 and 1.96 ± 1.1 U/mL, after five and three days of inoculation with S. netropsis A-ICA and B. subtilis ALICA, respectively. Furthermore, the antioxidant activity of feather protein hydrolysate obtained by S. netropsis A-ICA and B. subtilis ALICA was evaluated using DPPH radical-scavenging activity, which exhibited a significant antioxidant potential with an IC50 value of 0.8 and 0.6 mg/mL. The 3D models of detected keratinases in both strains showed high similarity with subtilisin family. Further, the docking results clarified the importance of GSG and VVVFTP domains in B. subtilis and beta-keratin, respectively. The present study revealed the keratinolytic potential of S. netropsis A-ICA and B. subtilis ALICA in chicken feather degradation, which have potential application value and may be exploited as supplementary protein and antioxidant in animal feed formulations.

Molecular strategies to enhance the keratinase gene expression and its potential implications in poultry feed industry

“…Nowadays, Bacillus species are employed as effective commercial microbial platforms to generate a wide range of metabolites, including industrial compounds, surfactants, extracellular enzymes, and heterologous proteins. From a biological procedure & perspective, however, the pleiotropic effects resulting from the genetic alteration of particular genes that codify for global regulators (transcription factors) have not been widely implicated ( Jagadeesan et al, 2020 ; Abdelmoteleb et al, 2023 ). These tactics have gained prominence recently in Bacillus species due to their potential to boost the production efficiency of certain metabolites that are of industrial importance.…”

“…The use of genetic engineering (mutations, deletions, or overexpression) to global regulators like Spo0A, CcpA, CodY, and AbrB has been increasingly popular recently. This trend can be advantageous for the development or enhancement of biotechnology that uses Bacillus species as manufacturing platforms ( Abdelmoteleb et al, 2023 ). To link the relationships between these regulators—which are crucial to take into account for use in the improvement of metabolites of commercial interest—genetic networks, regulation pathways, and their relevance to the development of growth stages are also reported ( Xiang et al, 2020 ; Abdelmoteleb et al, 2023 ).…”

“…This trend can be advantageous for the development or enhancement of biotechnology that uses Bacillus species as manufacturing platforms ( Abdelmoteleb et al, 2023 ). To link the relationships between these regulators—which are crucial to take into account for use in the improvement of metabolites of commercial interest—genetic networks, regulation pathways, and their relevance to the development of growth stages are also reported ( Xiang et al, 2020 ; Abdelmoteleb et al, 2023 ). The reported yields from these products, which are presently produced primarily in laboratories and to a lesser extent in bioreactors, are also examined to provide insightful information about their possible applications and the developmental stage aimed at enormous-scale process improvement ( Tolibia et al, 2023 ).…”

Isolation, Identification, and Screening of Keratinase Producing Bacteria from Soil and Production Optimization Using Feather Waste as Substrate

“…Due to vast increase of poultry industry business, an enormous compost waste is being generated every day amongst which feathers are the most important ingredient factor which could be utilized. According to Abdelmoteleb et al (2023), 10% of the chicken's body weight is thought to be made up of keratin protein, which makes up 90% of the feather structure. Based on the amount of sulphur in its structure, keratins are divided into two type's hard and soft keratin (Zhang et al, 2009).…”