镁离子浓度对氧化亚铁硫杆菌生长动力学的影响

在氧化亚铁硫杆菌(T.f)培养过程中其他营养物质足量的情况下,通过考察不同初始Mg2+浓度对氧化亚铁硫杆菌(T.f)生长活性的影响,得到在不同Mg2+浓度下细菌的生长曲线。结果表明:T.f对Mg2+具有一定的耐受能力;当培养基中ρ(Mg2+)≤10 g/L时,Mg2+对细菌生长活性影响很小;其ρ(Mg2+)为15 g/L时,Mg2+开始产生延迟效应,抑制细菌生长;ρ(Mg2+)为20 g/L时,细菌生长完全受到抑制。同时利用基于存在非竞争性抑制的Monod方程,建立了T.f在高Mg2+浓度下的生长动力学方程模型,确定在不同条件下细菌生长动力学参数,包括最大比生长速率μmax、Monod常数Km及镁离子抑制常数KI。利用correl系数工具分析细菌比生长速率的实验值和模拟值之间的相关系数为0.973,表明该动力学方程能较好地描述Mg2+浓度对氧化亚铁硫杆菌生长的影响。

Effect of magnesium ion concentration on growth kinetics of Thiobacillus ferroxidans

When the other nutrients were sufficient in the culture of Thiobacillus ferrooxidans,the impact of the different initial Mg2+concentration on the activity of the growth of Thiobacillus ferrooxidans was studied,and the bacterial growth curves were obtained at different magnesium ion concentrations.The results of the experiment show that Thiobacillus ferrooxidans is tolerant to Mg2+ some extent.No bad effect on the growth and activity of Thiobacillus ferrooxidans by Mg2+ is brought when cultured in 9K medium containing ρ(Mg2+)≤10 g/L.The growth and activity of Thiobacillus ferrooxidans are obviously influenced by Mg2+when ρ(Mg2+) is 15 g/L.When the concentration of Mg2+is around 20 g/L,the growth and activity of Thiobacillus ferrooxidans are completely inhibited.Simultaneously the kinetic model for the growth of Thiobacillus ferrooxidans at high magnesium ion concentrations is deduced on the basis of the non-competitive inhibition of the Monod equation.The values of kinetic parameters(i.e.maximum growth rate μmax,Monod constant Km and magnesium ion inhibition constant KI) under different initial experiment conditions are determined.The correlation coefficient between the simulated and experiment specific growth rates is 0.973,which shows that the kinetics equation can well describe the effect of magnesium ion concentration on the growth of Thiobacillus ferrooxidans.