Yu Wenhui, Wang Yitian, Han Jin, Hu Dan, Zhao Chenbing, Liu Zhenmin, Wu Zhengjun
State Key Laboratory of Dairy Biotechnology, Shanghai Engineering Research Center of Dairy Biotechnology, Dairy Research Institute, Bright Dairy & Food Co., Ltd, Shanghai, 201103, China.
College of Food Sciences & Technology, Shanghai Ocean University, Shanghai, 201306, China.
Biol Trace Elem Res. 2025 Apr 10. doi: 10.1007/s12011-025-04608-y.
Lead (Pb) is a widespread heavy metal pollutant that presents substantial risks to ecological systems and human health. The utilization of probiotic lactic acid bacteria (LAB) for the detoxification of Pb(II) in the host has aroused great interest. However, few studies had focused on the roles of capsular polysaccharide (CPS) in the bacteria adsorption of Pb(II). In the present study, L. fermentum B44 was selected out of nine lactobacilli for its superior absorption capacity of Pb(II) in vitro. The adsorbed Pb(II) ions by B44 cells were predominantly enriched on the capsule. Removal of the CPS from cells of strain B44 by 1 mol/L guanidine hydrochloride (GuHCl) would decrease the adsorption capacity of the host cells. The CPS showed a high capacity for Pb(II) adsorption, and its adsorption behaviour was more accurately described by the Langmuir isotherm model (R = 0.97) than by the Freundlich isotherm model (R = 0.907). Adsorption of Pb(II) ions would lead the CPS transforming from stacked, porous flakes to rough, condensed ones, with Pb(II) sediment on the CPS surface. Amide groups in B44 CPS were crucial in the adsorption of Pb(II). Our results provided intuitive evidence of the Pb(II) adsorption site on B44 cells and the protection of CPS to the bacterial cells.
铅（Pb）是一种广泛存在的重金属污染物，对生态系统和人类健康构成重大风险。利用益生菌乳酸菌（LAB）对宿主中的Pb（II）进行解毒已引起了极大的兴趣。然而，很少有研究关注荚膜多糖（CPS）在细菌吸附Pb（II）中的作用。在本研究中，从九种乳酸菌中筛选出发酵乳杆菌B44，因为其在体外对Pb（II）具有优异的吸收能力。B44细胞吸附的Pb（II）离子主要富集在荚膜上。用1 mol/L盐酸胍（GuHCl）去除B44菌株细胞中的CPS会降低宿主细胞的吸附能力。CPS对Pb（II）具有高吸附能力，其吸附行为用Langmuir等温线模型（R = 0.97）比用Freundlich等温线模型（R = 0.907）描述得更准确。Pb（II）离子的吸附会导致CPS从堆叠的多孔薄片转变为粗糙的凝聚薄片，Pb（II）沉积在CPS表面。B44 CPS中的酰胺基团在吸附Pb（II）中起关键作用。我们的结果为B44细胞上Pb（II）的吸附位点以及CPS对细菌细胞的保护提供了直观证据。
