Production and characterization of extracellular protease from biocontrol strain Bacillus licheniformis TG116

Abstract:

[Background] Bacillus licheniformis TG116 isolated from Typhonium giganteum Engl is a biocontrol strain with broad-spectrum against plant pathogens. [Objective] In order to optimize the enzyme production conditions of TG116 and explore its enzymatic properties. [Methods] The optimization of enzyme production conditions and the enzymatic properties of proteases were investigated by Folin-Phenol chromogenic method and response surface methodology. [Results] The optimal enzyme conditions to produce strain TG116 were temperature 40.83 °C, pH 8.01, and fermentation time 53.74 h and increasing aeration could significantly enhance enzyme activity. After 48 hours of incubation under optimized conditions, the protease activity of the supernatant reached 254.07 U/mL from 57.46 U/mL. The protein was alkaline protease, with optimum pH 8.5, the optimum temperature 50 °C and it has good temperature and pH stability. EDTA had strong inhibitory effect on enzyme activity and metal ions Mg2+, Ca2+, Na+, Co2+, K+ also have showed a certain inhibitory effect. [Conclusion] Strain TG116 has great pH and temperature stability. The proteases are not easily inactivated in practical applications, which can decompose the cell wall protein components of fungi and destroy the cell wall structure, thus inhibiting and even killing pathogenic bacteria to achieve antibacterial effects.

Key words:Alkaline protease, enzyme production conditions, enzymatic properties