一株肉葡萄球菌的降镉特性与机制研究

Cadmium-lowing properties and mechanism of a strain of Staphylococcus carnosus

该文对从实验室筛选出的具有强耐镉能力的肉葡萄球菌(Staphylococcus carnosus)846进行了降镉特性和降镉机制的研究。分析了pH值、Cd^(2+)浓度、菌体浓度和其他金属离子等因素对其降镉能力的影响,并通过扫描电镜,能谱和傅里叶光谱探究了该菌的降镉机制。结果表明,当pH值为5,Cd^(2+)质量浓度为50 mg/L和菌体质量浓度为1 g/L时,菌体的降Cd^(2+)效率最高;Mg^(2+)、Pb^(2+)和Zn^(2+)等金属离子的存在会对菌体的降Cd^(2+)效果产生负面影响,而Cr^(^(6+))的存在提高了菌体的降Cd^(2+)能力。Cd^(2+)的存在主要会使细胞表面发生褶皱,变得粗糙,甚至使细胞破裂。能谱结果证明Cd^(2+)在细胞表面的积累。细胞表面的—OH、—CH_(2)—、CH_(2)/CH_(3)、—C—OH和P=O等基团参与了菌体的降Cd^(2+)过程。因此,肉葡萄球菌846具有一定的降镉潜力,为降镉乳酸菌的开发提供了依据。

This paper aimed to investigate the cadmium-lowering properties and mechanisms of Staphylococcus carnosus 846 with high cadmium tolerance.The effects of pH,Cd^(2+)concentration,bacterial concentration and other metal ions on its cadmium-lowering ability were analyzed,and the mechanism of cadmium-decrease was investigated by scanning electron microscopy,energy dispersive spectrometer(EDS)and mid-infrared Fourier spectroscopy.The results showed that the cadmium-lowering efficiency of the strain reached the maximum at pH 5,with the Cd^(2+)concentration for 50 mg/L and the concentration of the bacterium for 1 g/L.The presence of other metal ions such as Mg^(2+),Pb^(2+)and Zn^(2+)reduced the Cd^(2+)lowering effect of the strain,while the presence of Cr^(6+)enhanced its Cd^(2+)lowering ability.The presence of Cd^(2+)mainly caused the cell surface wrinkling,rough and even cell rupture.The EDS results demonstrated the Cd^(2+)accumulated mainly on the cell surface.The—OH,—CH_(2)—,CH_(2)/CH_(3),—C—OH and P O groups on the cell surface were involved in the Cd^(2+)lowering process of S.carnosus 846.Therefore,S.carnosus 846 were demonstrated having cadmium reduction potential,which provided a basis for the development of cadmium-lowering lactic acid bacteria.