2-KGA混菌发酵大小菌耦合关系研究及建模

研究了维生素C前体2-酮基-L-古龙酸(2-KGA)混菌发酵巨大芽孢杆菌(俗称大菌)与普通生酮古龙酸菌(俗称小菌)的耦合关系。经研究发现:(1)大菌通过群体感应调整自身生长行为;(2)大菌活菌代谢物及其自溶物质弥补小菌代谢缺陷促进小菌生长;(3)小菌可能通过释放溶菌酶促使大菌自溶;(4)大菌自溶释放一些蛋白酶类物质提高小菌山梨糖脱氢酶(SDH)活性从而加速产物形成。基于以上研究建立了2-KGA混菌发酵的动力学模型,并用实验数据证明了模型的有效性。

Modeling on interaction of different strains in 2-KGA mixed culture fermentation

The interaction between Bacillus megaterium(also called big bacterium)and Ketogulonicigenium vulgare (also called small bacterium)was studied for 2-keto-L-gulonic acid (2-KGA)mixed culture fermentation.The following mechanisms were found.(1)Big bacterium might adjust its growth behavior by quorum sensing.(2)Metabolites and autolysis substances of big bacterium were beneficial to overcoming the metabolic defects of small bacterium and therefore accelerating the latter's growth.(3)Small bacterium released lysozyme to promote big bacterium's autolysis.(4)Big bacterium autolysis released specific protease substances to enhance sorbitol dehydrogenase (SDH)which might increase the synthesis rate of 2-KGA.Based on such mechanisms,a kinetic model of 2-KGA mixed fermentation was established.Model validation was carried out with four sets of experimental data under different cultivation conditions.The results demonstrated that the proposed model was able to well describe the growth of two bacteria and 2-KGA production.