Bacillus mucilaginosus and high-density fermentation method and use thereof

A two-stage fermentation process of producing Bacillus mucilaginosus, comprising the following steps:

• (1) Inoculating Bacillus mucilaginosus HSCUP-76-8 on a slanting culture medium for activation, with temperature controlled at 29-33° C., culturing for 24-48 hours to obtain an original slanting inoculum, then inoculating the original slanting inoculum on the slant medium and culturing under the same condition to obtain a slanting inoculum;
• (2) Inoculating said slanting inoculum in a liquid culture medium with 50-100 ml medium per 250 ml shake flake, culturing at temperature 29-33° C., rpm 160-220 r/min, for 8-12 hours on a shake bed, to obtain a mother inoculum;
• then inoculating the mother inoculum in a shake-flask medium, and culturing under the same condition, to obtain a liquid of shake-flask inoculum;
• (3) Culturing using a seed fermentation medium, with charging coefficient of 0.7-0.8, steam sterilization under 121° C. for 20 minutes, inoculum size of 5%-10%, culturing temperature of 29˜33° C., air flow of 1:0.8˜1.0 (v/v·min), controlling the dissolved oxygen saturation DO value at 10%˜30% using a speed agitator, pH value controlled in the range of 7.2±0.2, culturing for 8-12 hours, to obtain a liquid inoculum of fermentation seed at log phase;
• (4) First stage fermentation culturing, using basal fermentation medium, with charging coefficient of 0.7-0.8, steam sterilization under 121° C. for 20 minutes, inoculum size of 5%-10%;
• temperature at 29˜33° C., pH value controlled in the range of 7.0-7.2, air flow 1:0.8˜1.2 (v/v·min), controlling the dissolved oxygen saturation DO value at 20%˜30% using a speed agitator, and using vegetable oil as antifoam agent for the controlling of the foam;
• sampling in every 4 hours, then examining the number and morphologies of bacteria under a microscope, and conducting chemical analysis of sugar and ammoniacal nitrogen;
• ensuring appropriate feeding according to the examination result to control sugar dose at 2 g/L˜3 g/L, and controlling nitrogen source with NH4Cl at 0.5 g/L˜0.1 g/L, then stopping the nitrogen supply towards the end of the log phase;
• (5) Second stage fermentation culturing at temperature 33-37° C., pH value in the range of 7.2-8.9, airflow 1:1.0˜0.8 (v/v·min), controlling the dissolved oxygen saturation DO value as 5%˜10% using a speed agitator, then adding calcium carbonate to promote sporulation;
• terminating fermentation when endospores occupy the entire visual field under microscopic examination, and storing for later usage.