Characteristics Research Of Selenium-Containing Bacillus Subtilis And Antimicrobial Applications

This work aims to transform the inorganic which has a certain toxicity and inefficient, such as selenite and senate and so on, to non-toxicity and efficient organic form, slenocysteine, using bio transform by Bacillus subtilis. Therefore, it can advance the availability of selenium and improve the deficiency of selenium. The main research in this paper were as follows:1. Studying the effects of selenium addition on growth by Bacillus subtilis, found the best added condition of sodium selenium. The results showed, it had acceleration effect on the growth of Bacillus subtilis in 0~60μg/mL sodium selenite, whereas inhibiting effect was found in 90~120μg/mL sodium selenite. The best added concentration of sodium selenite was 45μg/mL, added time was 4h, additive amount of Bacillus subtilis was 2%, at this site the conversion rate of inorganic was 76.3±3.4%.2. The added of sodium selenite can influence the fermentation ability of Bacillus subtilis. With the increase of additive concentration by sodium selenite, the alkaline protease activities of Bacillus subtilis decreased except the optimum growth conditions had a slight increase, while the variation of neutral protease activity has no significant differences ranged in 1000~1100μg/ml. Added selenium had a positive impact on anti-microbial ability of strains.3. The effects of amino acid and sodium selenite addition on antimicrobial activities by Bacillus subtilis, it found the results as follows: the antimicrobial substance had shown at 28 th h of Bacillus subtilis, but added sodium selenite can improve the antimicrobial ability, in the other side, it could advance 4h in the produce of antimicrobial substance. The antimicrobial had the best effects when amino acid added at 24 h. After added sodium selenite, concentration of Glu was 100μg/ml, Asp was 200μg/ml, Pro was 200μg/ml can improve the growth of Bacillus subtilis obviously; Glu was 200μg/ml, Asp was 200μg/ml, Pro was 50μg/ml, the antimicrobial activities achieve the best.4. Using Matlab software to build the ANNs, the effects of temperature, pH, salt level and selenium concentration on growth, alkaline and organic conversion rate by Bacillus subtilis. Two ANNs models(BP network and RBF network), compared with response surface method(RSM), the results showed, BP network model can predict more accurately. Through optimized the ANNs by GAs can predict accurately and regulation variable, applied in production better.