葡萄糖酸促进氧化亚铁硫杆菌磁小体合成的发酵动力学

Fermentation kinetics of Acidithiobacillus ferrooxidans for magnetosome synthesis improved by gluconic acid addition

【目的】明确不同种类有机物对氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)BYM磁小体形成的促进作用,为安全有效提升细菌磁小体产量提供新思路。【方法】以A.ferrooxidans BYM为目的菌株,采用单因素试验分析10种有机物对A.ferrooxidans BYM亚铁氧化的影响,通过4 L发酵体系进一步筛选促进磁小体合成的有机物;通过分批发酵实验基于经典发酵动力学模型(Logistic、Luedeking-Piret、底物消耗动力学方程)分别构建A.ferrooxidans BYM菌体生长、磁小体合成以及亚铁消耗动力学模型。【结果】筛选得到10 mmol/L葡萄糖酸能使磁小体产量最高达到2.00×10^(-3)g/L,葡萄糖酸使A.ferrooxidans BYM细胞呈椭圆形,表面光滑;在葡萄糖酸作用下,A.ferrooxidans BYM的发酵符合Logistic、Luedeking-Piret、底物消耗动力学方程。【结论】添加10 mmol/L葡萄糖酸能够使A.ferrooxidans BYM磁小体产量提升8倍,葡萄糖酸通过改变细胞形态和表面结构促进磁小体合成,菌体生长、产物生成以及底物消耗动力学模型可以阐明A.ferrooxidans BYM在葡萄糖酸存在下的分批发酵过程。

[Objective]To clarify the promotion effects of different organic compounds on the formation of magnetosomes in Acidithiobacillus ferrooxidans BYM,so as to provide a new idea for safely and effectively improving the magnetosome yield.[Methods]Single-factor experiments were conducted to measure the effects of ten organic compounds on the ferrous oxidation of A.ferrooxidans BYM,and the organic compounds promoting the synthesis of magnetosomes were further screened by a 4 L fermentation system.The classical kinetic models(Logistic,Luedeking-Piret,and substrate consumption kinetic equations)were employed to build the kinetic models for the growth,magnetosome synthesis,and ferrous consumption of A.ferrooxidans BYM by batch fermentation experiments.[Results]The maximum magnetosome yield(2.00×10^(−3) g/L)was achieved with the addition of 10 mmol/L gluconic acid,in the presence of which the bacterial cells were oval and had a smooth surface.With the addition of gluconic acid,the fermentation kinetics of A.ferrooxidans BYM was in accordance with Logistic,Luedeking-Piret,and substrate consumption kinetic equations.[Conclusion]The addition of 10 mmol/L gluconic acid increases the magnetosome yield of A.ferrooxidans BYM by eight times.Gluconic acid changes the cell morphology and surface of A.ferrooxidans BYM.The kinetics models of cell growth,product formation,and substrate consumption can illustrate the batch fermentation of A.ferrooxidans BYM in the presence of gluconic acid.