一株耐硝酸盐的巨大芽孢杆菌溶磷特性研究

以多种磷源培养基培养巨大芽孢杆菌(Bacillus megatherium)NCT-2,研究了该菌的溶磷特性.结果表明,在以磷酸钙为磷源时,溶磷效果随菌株的生长而发生变化,在第2 d菌株生长量最大,溶磷效果最好;不同碳氮源会影响菌株的溶磷效果,菌株优先利用葡萄糖,其次为麦芽糖和蔗糖,而对淀粉的利用能力较差;对氮源的利用顺序依次为(NH4)2SO4NH4Cl尿素Na NO2KNO3;磷酸钙的浓度会影响菌株溶磷效果,浓度过低或过高都会导致溶磷量过低.菌株对多种难溶性含磷物溶解效果的研究表明,菌株对植酸钙溶磷量最高,为98.1 mg·L-1,对Fe PO4、Al PO4的溶解能力稍弱,在30~40 mg·L-1之间,对卵磷脂溶磷量最小,为6.15 mg·L-1.通过对培养基中磷酸酶活性和有机酸进行分析,初步研究了NCT-2的溶磷机制,发现该菌通过产生酸性磷酸酶、碱性磷酸酶或产酸溶解难溶磷,不同磷源的溶磷机制有所不同.

Phosphate solubilizing characteristics of a nitrate-tolerating bacterium, Bacillus megaterium

To evaluate the phosphate solubilizing ability of Bacillus megatherium NCT-2, cells were incubated in the culturing medium with different insoluble phosphate compounds. When calcium phosphate was used as the phosphate source, the phosphate concentration in the medium changed with the growing of the strain, and reached the maximum on the second day. The effects of different carbon and nitrogen sources on the phosphate solubilizing ability were also investigated. The utilizing efficiency order of carbon sources was glucose>maltose>sucrose>starch, and for the nitrogen sources was ammonium sulfate>ammonium chloride>urea>sodium nitrite>potassium nitrate. The concentration of calcium phosphate also affected phosphate solubilizing ability, extreme high or low of the calcium phosphate concentration would both lead to a low dissolving phosphate content. This strain showed significant phosphate solubilizing ability with different insoluble phosphates, with the maximum dissolving phosphate content as 98.1 mg·L^-1, 30~40 mg·L^-1and 6.15 mg·L^-1, respectively, for different phosphate sources as phytin, FePO₄, AlPO₄ and lecithin. The mechanism of phosphate solubilizing was that the strain could produce phosphatase or organic acid to help to dissolve the insoluble phosphate.