Production, optimization, purification, kinetic analysis, and applications of alkaline proteases produced from Bacillus subtilis through solid-state fermentation of agricultural byproducts

الملخص EN

Proteases have gained commercial value due to multiple applications in different industrial sectors.

the current research aimed to use cheaper agricultural waste for optimal protease production.

the maximum level of protease production was achieved at 37 °C, an incubation period of 24 h, pH 9.0, inoculum size 3%, 1.5 g sucrose as a carbon source, and 30% moisture content by using solid-state fermentation.

Ammonium nitrate and yeast extract tremendously increased protease production among the various inorganic and organic nitrogen sources.

Ca²+ ions and Tween 40 showed optimal protease production among the tested metal ions and surfactants.

protease purification was carried out by ammonium sulphate precipitation followed by Sephadex G-100 gel filtration chromatography.

the purification resulted in 1.3-fold of purified protease with 51.5U/mg specific activity and a total yield of 37.5 %.

the molecular weight of purified protease was confirmed upon SDS PAGE with a single band of -36 kDa.

the protease was stable over a temperature range of 35-45 °C and pH 7-9, with maximal activity at 40 °C and pH 9.

the kinetic parameters Vmax (maximum rate) and Km (Michaelis-Menten constant) were calculated as 0.307 U/g and 11.2 mg/mL, respectively.

the alkaline protease significantly dehair the goat skin and successfully removed the animal blood stain from cotton cloth.