Regulation Of Production Process Of Aminopeptidase Fermentated By Bacillus Cereus CZ

Aminopeptidase is a kind of hydrolytic enzymes, freeing the amino acids from the N-ter-minal sequence of the proteins or peptides, mainly used in the food industry. In order to und-erstand the basic conditions for production control, the thesis, with Bacillus cereus CZ, werecarried out sereval experiments, including carbon source and nitrogen source’s effect on theproduction of aminopeptidases, the optimization of medium and regulation in2L fermentati-on fermentor.The research about carbon source’s effect on the production of aminopeptidases includedthe test of carbon sources’ selection, sample measureed every8h, comparison of different ca-rbon source concentrations and measurement of the accumulation curve. At the same time, theby-product enzymes were detected. Results show that the greatest impact on the production ofaminopeptidases by the strain is L-arabinose, best point is40g·L^-1. Enzyme accumulation cu-rve showed that at72h, enzymes reached the highest. With the detection of the by-product e-nzyme, Results indicate that L-arabinose isomerase and aminopeptidase have the same variat-ion tendency, so, presumably, aminopeptidase and L-arabinose have certain coordinateon rel-ationnship.Nitrogen source’s effect on the production of aminopeptidases by the strain was studiedfrom the following sides, including selection of nitrogen source, concentration identified, am-ino acids supplied and inorganic nitrogen sources added. Results show that the yeast powderis the best nitrogen source, the best concentration10g·L^-1. Among the amino acids, serine, tr-yptophan, lysine, glycine and glutamine have greater impact, the best added time is the initialfermentation time （0h）, the best added concentrations were2g·L^-1,4g·L^-1,8g·L^-1,8g·L^-1,4g·L^-1respectively. When amino acids blended, combination of tryptophan, lysine, glycine andglutamine has greater impact. When ammonium sulphate, ammonium chloride and urea wereadded, the best concentration5g·L^-1,3g·L^-1,10g·L^-1, the best added time12h, and ammoni-um sulphate’s effect is the most remarkable.Bsaed on the above experiments, PB design experiment and RSM experiment were usedto optimize culture conditions of the production of aminopeptidases. The results of single fac- tor experiments display that the best rotation speed is200r·min^-1, temperature37℃, pH8.0,metal Zn²⁺0.5g·L^-1. PB experiment shows that L-arabinose, yeast powder and Zn²⁺are the m-ost remarkable influence factors. The steep test and RSM experiment show the best combinat-ion is L-arabinose30.84g·L^-1, yeast extraction powder25.76g·L^-1, Zn²⁺0.3920g·L^-1, the pr-edicted result of the production of aminopeptidases is96.57U·mL^-1. The validated result was94.48U·mL^-1, as a result, the models developped were considered to be accurate and reliablefor predicting the production of LAP by B. cereus CZ. Through fermention in2L fermenter,the best condition for LAP production is rotation speed500r·min^-1, pH8.0and temperature37℃. The production curve indicates that the max production of LAP is94.28U·mL^-1.This research has carried out more comprehensive studies on the production regulationof LAP by Bacillus cereus CZ, helpful to improve the yield of LAP and build high-yieldingstrains, and useful for regulating industrial production...