| Based on the literature have been reported and early experimental data in our laboratory show that the production of prodigiosin produced by Serratia marcescens in peanut medium will be significantly improved, so select different single factors to add in the medium1%peptone,3%Tween-80,0.2%KCl,then detect the number of bacteria and PG Yield. The aim is to find out a certain monomer significantly improve the production of prodigiosin from peanut. Besides that we have study the regulatory effect of the other factors which can affect the production of PG by Serratia marcescens (such as glucose, amino acids, inorganic salts, culture conditions), then analyze and discuss the regulatory mechanisms of these factors.The experimental results are as follows:1) The exploring of the key regulatory factors in peanut ingredients and its control mechanism Peanut oil can promote the growth of bacteria and PG synthesis. However, the free fatty acids are opposite. The monomer triolein is a key regulator of peanut medium increased PG production. Its regulation mechanism first as a high-quality carbon source to cause the massive growth of bacteria and PG production, the second is as a surfactant to change the permeability of the bacterial cell membrane, prompting PG release from intracellular to extracellular.2) The influence of glucose0.4%glucose can be used as a carbon source to promote growth of Serratia marcescens and PG production, compared with the no glucose group add to o.4%glucose can shorten the initial production of PG about12h,then it will appear Crabtree effect when the concentration is above2%.3) The influence of metal ions①0.1%NaCl plays a significant inhibitory effect on the number of bacteria and the production of PG;0.2%KCl provide a suitable osmolality to promote the growth of bacteria and the production of PG;②0.1%MgCl2as the enzyme agonists in PG synthesis process is up-regulation;0.05%CaCl2can completely inhibit the synthesis of PG.③the addition of Fe2+、Zn2+、Fe3+have no influence on the number of bacteria;0.1%Fe2+makes the production of PG sharply declined;0.05%Zn2+can completely inhibit the synthesis of PG;0.005%;Fe3+can decline the production of PG, but the PG decrease and the concentration of Fe3+is basically irrelevant.4) The influence of amino acids1%proline as the precursor substance of one of the pyrrole ring in prodigiosin biosynthesis pathway to increase the yield of PG;0.5%glycine and0.05%serine have significant downward effect5) The influence of culture conditions dark culture is conducive to bacterial growth and also to avoid the PG long light decomposition occurs to improve the PG production; The optimal pH is6.0, liquid volume is50ml (250ml).0.05%CaO2in aqueous solution can provide sustain oxygen for the bacteria in the fermentation broth,and its hydrolysis product Ca (OH)2can improve the pH of the fermentation broth, so it is conducive to the growth of bacteria and PG production.Through this experiment, not only find out the monomer triolein from the peanut is a key regulator of peanut medium increased PG production, but also expound its regulatory mechanism, first as a high-quality carbon source to cause the massive growth of bacteria and PG production, the second is as a surfactant to change the permeability of the bacterial cell membrane, prompting PG release from intracellular to extracellular. Combined with the analyze of the other regulatory factors, we consider that carbon source, a surfactant and dissolved oxygen in the medium have greater impact on PG production in Serratia marcescens ultimately... |
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