Abstract：
Phosphate-solubilizing bacteria (PSB) promotes the formation of mineralized precipitation through phosphorous dissolution and mineralization, forming stable lead (Pb(II)) minerals and reducing the migration of Pb(II) in the environment. In this study, a Pb-tolerant strain Ochrobactrum sp. J023 from a contaminated soil around a battery factory in Jiangsu Province, China, was screened for experiments to investigate the phosphate solubilization and mineralization mechanism of this strain. The organic acids and the acid phosphatase produced by the bacteria have a synergistic effect on phosphate dissolution. When the pH of the culture medium decreased to the lowest 4.55, the amount of soluble phosphate and the activity of acid phosphatase reached the maximum 161.29 mg L-1 and 61.98 U mL-1, and there was a significant correlation between the concentration of soluble phosphate and the activity of acid phosphatase (R = 0.832**, P < 0.05). It was found that acetic acid played the most important role in the secreted organic acids. During the mineralization reaction, the extracellular polymeric substances (EPS) chelates part of the Pb(II) on the surface of the cell wall, preventing the metal Pb from penetrating into the cell, thus providing protection to the strain. Meanwhile, due to the nucleation sites provided by cell surface groups (carboxyl and phosphate groups), a large number of metal ions are absorbed to promote the formation of crystallization. The final mineralized product of Pb(II) by strain J023 was pyroxite (Pb5(PO4)3X, where X = Cl, OH). The mechanism of phosphate dissolution and mineralization proposed by us is that the organic acids and acid phosphatases secreted by phosphate-solubilizing bacteria promote the increase of PO43- concentration in the solution, the complexation of metal cations and cell surface groups will induce the formation of mineralized precipitation under the catalysis of enzyme. Therefore, it is a promising strategy for bioremediation of lead pollution by screening functional strains with strong abilities of phosphate solubility and mineralization.
摘要：
增磷细菌（PSB）通过磷的溶解和矿化促进矿化沉淀的形成，形成稳定的铅（Pb（II））矿物并减少Pb（II）在环境中的迁移。在这项研究中,一种耐铅的嗜铬杆菌属菌株。J023来自江苏省一家电池工厂周围的污染土壤，中国,筛选了该菌株的磷酸盐溶解和矿化机理。细菌产生的有机酸和酸性磷酸酶对磷酸盐溶解具有协同作用。当培养基的pH下降到最低4.55时，可溶性磷酸盐的量和酸性磷酸酶的活性达到最大161.29mgL-1和61.98UmL-1，可溶性磷酸盐的浓度与酸性磷酸酶的活性之间存在显着相关性（R=0.832**，P<0.05)。发现乙酸在分泌的有机酸中起着最重要的作用。在矿化反应过程中,胞外聚合物（EPS）在细胞壁表面螯合部分Pb（II），防止金属铅渗入细胞，从而为菌株提供保护。同时,由于细胞表面基团（羧基和磷酸基团）提供的成核位点，大量的金属离子被吸收以促进结晶的形成。应变J023的Pb（II）的最终矿化产物是辉铁矿（Pb5（PO4）3X，其中X=Cl，OH).我们提出的磷酸盐溶解和矿化的机理是，溶磷菌分泌的有机酸和酸性磷酸酶促进溶液中PO43-浓度的增加，在酶的催化下，金属阳离子与细胞表面基团的络合会诱导矿化沉淀的形成。因此,通过筛选具有较强磷酸盐溶解性和矿化能力的功能菌株，是一种有前途的铅污染生物修复策略。
