Role of casein on induction and enhancement of production of a bacterial milk clotting protease from an indigenously isolated Bacillus subtilis

Abstract

Aims: To isolate and enhance the yield of a bacterial milk clotting protease (MCP) through process optimization and scale up. Materials and Results: Bacillus subtilis was isolated as MCP producer with good milk clotting activity (MCA) per proteolytic activity (PA) index. The enzyme production was inducible with casein and enhanced with fructose and ammonium nitrate resulting in 571·43 U ml−1 of enzyme. Conclusions: Medium containing 4% fructose, 0·75% casein, 0·3% NH4NO3 and 10 mmol l–1 CaCl2, pH 6·0, inoculated with 4% (v/v) inoculum, incubated at 37°C, 200 rev min−1 for 72 h gave maximum production. A 6·67‐fold increase in MCP yield with very high MCA per PA index was observed after final optimization indicating similarity to rennets. Significance and Impact of the Study: Mostly fungal MCPs have been reported. The MCA and MCA per PA index of this bacterium is comparable to that of many fungal reports and better than quite a few bacterial MCPs. Thus, this enzyme by B. subtilis has good probability of successful use in cheese production.

Production of Milk-Clotting Protease from Bacillus subtilis

“…A final yield of 571.43 U/ml was obtained after one at a time optimization under submerged conditions [5]. Therefore, in the present investigation, three strategies for production viz.…”

“…Production carried out with moistening agent supplemented with 0.25% casein yielded 215.0 U/g of MCA. There was no production of mcp in absence of casein (data not shown) [5].…”

“…Any change in their concentrations resulted in a drastic change; yet, these two are clearly synergistic in action. An increase in mcp yield with increase in [5]. Figure 3 indicates the negative effect of inoculum density on milk clotting protease production while the response varied as a function of agitation rate (Fig.…”

“…The organism, Bacillus subtilis obtained after extensive screening [5] was maintained on nutrient agar slants (pH 7.0) at 10±1°C in a bacteriological incubator with periodic subculturing.…”

Purification and characterization of Bacillus subtilis milk-clotting enzyme from Tibet Plateau and its potential use in yak dairy industry

“…Milk-clotting enzyme (MCE) is widely distributed in many organisms and tissues with different physiological properties and functions [2][3][4][5][6].…”