浮游球衣菌S9产铁氧化酶发酵条件优化及酶学特性研究

Optimization of fermentation conditions of Sphaerotilus natans S9 for ferroxidase production and its enzymatic properties

通过单因素及正交设计试验,研究了浮游球衣菌S9产铁氧化酶的发酵条件,并探讨了铁氧化酶的酶学性质。结果表明,菌株S9的最适产酶发酵培养基配方为柠檬酸铁铵1.0%,NH_4Cl 0.1%,K_2HPO_40.05%,Mg SO_4·7H_2O 0.05%,Ca Cl_2·6H_2O 0.01%;最佳发酵条件为:培养初始p H7.0,培养温度30℃,装液量50 m L/250 m L,转速150 r/min,培养时间84 h。在此优化发酵条件下,菌株S9的铁氧化率可达75.25%,与未优化前相比,提高了42.28%。所产铁氧化酶的最适温度为30℃,最适p H为7.5,Mg^(2+)、K^+、Na^+对酶的活性具有增强作用,Pb^(2+)、Ag^+会抑制酶的部分活性,且Mn^(2+)、Zn^(2+)对酶具有很强的抑制作用。对该菌最适培养基和产酶条件及酶学性质,对铁氧化酶在给排水工程及其分离纯化和活性保护具有一定的参考价值和指导意义。

Fermentation conditions of Sphaerotilus natans S9 for ferroxidase production were studied by single factor and orthogonal experiments, and the enzymatic properties of ferroxidase were studied. The results showed that the optimum fermentation medium of strain S9 was ferric ammonium citrate 1.0%, NH4Cl0.1%, K2HPO4 0.05%, MgSO 4·7H2O 0.05%, CaC l2·6H2O 0.01%. The optimum fermentation conditions were as follows： initial pH 7.0, culture temperature 30 ℃, liquid volume 50 ml/250 ml, rotational speed 150 r/min, culture time 84 h. Under the fermentation conditions, the ferro-oxidation rate of strain S9 can reach 75.25%, and ferro-oxidation rate increased 42.28% compared to that of before optimization. The optimum temperature and pH of ferroxidase were 30 ℃ and 7.5, respectively. Mg2＋, K＋, Na＋ had certain activation on ferroxidase, Pb2＋, Ag＋ had inhibitory effect on the enzyme activity, while Mn2＋, Zn2＋ had very strong inhibition on ferroxidase activity. The study on the optimum culture medium, enzyme pro-duction conditions and enzymatic properties was of certain reference value and guiding significance for the purification and protection of the enzyme in water supply and drainage engineering.