Optimizing the fermentation conditions and enhanced production of keratinase from Bacillus cereus isolated from halophilic environment

Abstract

Keratinase degrading Bacillus cereus was isolated from the halophilic environment in Tamilnadu, India and keratinase production was optimized using wheat bran substrate. Of the screened bacterial isolates, four were found to have the ability to produce keratinolytic enzyme. The process parameters were optimized using one-variable-at-a-time approach and response surface methodology. Supplementation of 1% lactose supported more keratinase production (120 U/g). Among the selected nitrogen sources, addition of casein significantly enhanced maximum keratinase production (132.5 U/g). Among the ions, manganese chloride significantly enhanced keratinsase production (102.6 U/g), however addition of zinc sulphate and copper sulphate decreased keratinase production. The maximum keratinase production was obtained in the wheat bran medium containing 1% lactose, 0.5% manganese with 80% moisture (292 U/g). Statistics based contour plots were generated to explore the variations in the response surface and to find the relationship between the keratinase yield and the bioprocess conditions.

Response Surface Methodology for the Optimization of Keratinase Production in Culture Medium Containing Feathers by Bacillus sp. UPM-AAG1

“…Many of the major commercial keratinolytic bacteria come from the genus Bacillus spp. [28,35], chiefly due to its generally regards as safe (GRAS) property [36]. The keratinolytic bacteria in this study were isolated from a poultry farm environment, and numerous keratinolytic bacteria have been isolated from poultry farm soils, such as Bacillus subtilis DP [25] and five keratinolytic strains of Bacillus spp.…”

Microbial Keratinase: Next Generation Green Catalyst and Prospective Applications

“…Inherent cell precursors, culture conditions, and nutrient availability are among the significant factors that influence microbial metabolites production (Parra et al, 2005). The genetic diversity of keratinolytic microorganisms affects the arbitrary selection of the physico-chemical fermentation conditions (Arokiyaraj et al, 2019). Additionally, the prolonged fermentation period for the keratinase production by most wild microbial producers affects keratinase yield and sustainability (Fang et al, 2019).…”

Structure, Application, and Biochemistry of Microbial Keratinases

“…Second, a medium for the microorganism growth needs to be set up. As the media for enriching bacteria or fungi are different, a suitable medium is important in the screening ( De Azeredo et al, 2006 ; Fakhfakh et al, 2011 ; Mazotto et al, 2013 ; Parrado et al, 2014 ; Arokiyaraj et al, 2019 ). In addition, other parameters such as cultural time and temperature should be considered based on the experimental objectives.…”

“…The species include Bacillus subtilis , Bacillus pumilus , Bacillus lichenifomis , and Bacillus cereus ( Zaraî Jaouadi et al, 2015 ; Bhari et al, 2018 ; Gegeckas et al, 2018 ). Some other bacteria are able to degrade feathers with a high efficiency ( Kim et al, 2005 ; Zaraî Jaouadi et al, 2015 ; Abdel-Naby et al, 2017 ; Arokiyaraj et al, 2019 ; Hamiche et al, 2019 ). Keratin-degrading fungi can be isolated from some tissues of human and animals as the produced keratinase might be important for the fungal infection ( Friedrich et al, 1999 ; Bohacz and Korniłłowicz-Kowalska, 2019 ; Zhang et al, 2019 ).…”

“…Based on the identified enzymes and the sequences deposited in databases, the molecular weights of keratinase range from 20 to 130 kDa ( Kanoksilapatham and Intagun, 2017 ; Sharma and Devi, 2018 ; Pinski et al, 2020 ; Qiu et al, 2020 ). The optimal conditions for enzymatic activity are diverse as different enzymes prefer different pH values, temperatures, and substrates ( Tatineni et al, 2007 ; Tiwary and Gupta, 2010b ; Rai and Mukherjee, 2011 ; Khodayari and Kafilzadeh, 2018 ; Arokiyaraj et al, 2019 ; Nnolim et al, 2020a ). The classification of keratinases based on the amino acid sequence provides a unique and clear view toward the function and mechanism of keratinases ( Qiu et al, 2020 ), which suggests that obtaining the amino acid sequence of the newly identified keratinases is an important task.…”