Wu Huiqing, Wu Qingping, Wu Guojie, Gu Qihui, Wei Linting
State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangzhou, Guangdong, China.
Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangzhou, Guangdong, China.
PLoS One. 2016 Apr 14;11(4):e0151479. doi: 10.1371/journal.pone.0151479. eCollection 2016.
The goal of this study was to identify Cd-resistant bacterial strains with endurance capacity and to evaluate their ability to remove cadmium ions from cadmium-polluted water. The Bacillus cereusS5 strain identified in this study had the closest genetic relationship with B. cereus sp. Cp1 and performed well in the removal of Cd2+ions from solution. The results showed that both the live and dead biomasses of the Cd2+-tolerant B. cereus S5 strain could absorb Cd2+ ions in solution but that the live biomass of the B. cereus S5 strain outperformed the dead biomass at lower Cd2+concentrations. An analysis of the cadmium tolerance genes of B. cereus S5 identified ATPase genes that were associated with cadmium tolerance and involved in the ATP pumping mechanism. The FTIR spectra revealed the presence of amino, carboxyl and hydroxyl groups on the pristine biomass and indicated that the cadmium ion removal ability was related to the structure of the strain. The maximum absorption capacity of the B. cereus S5 strain in viable spore biomass was 70.16 mg/g (dry weight) based on a pseudo-second-order kinetic model fit to the experimental data. The Langmuir and Langmuir-Freundlich isotherm adsorption models fit the cadmium ion adsorption data well, and the kinetic curves indicated that the adsorption rate was second-order. For Cd2+ concentrations (mg/L) of 1-109 mg/L, good removal efficiency (>80%) was achieved using approximately 3.48-10.3 g/L of active spore biomass of the B. cereus S5 strain. A cadmium-tolerant bacteria-activated carbon-immobilized column could be used for a longer duration and exhibited greater treatment efficacy than the control column in the treatment of cadmium-polluted water. In addition, a toxicity assessment using mice demonstrated that the biomass of the B. cereus S5 strain and its fermentation products were non-toxic. Thus, the isolated B. cereus S5 strain can be considered an alternative biological adsorbent for use in emergency responses to severe cadmium pollution and in the routine treatment of trace cadmium pollution.
本研究的目的是鉴定具有耐受能力的耐镉细菌菌株，并评估其从镉污染水中去除镉离子的能力。本研究中鉴定出的蜡样芽孢杆菌S5菌株与蜡样芽孢杆菌Cp1的亲缘关系最近，并且在从溶液中去除Cd2+离子方面表现良好。结果表明，耐Cd2+的蜡样芽孢杆菌S5菌株的活生物质和死生物质都能吸收溶液中的Cd2+离子，但在较低的Cd2+浓度下，蜡样芽孢杆菌S5菌株的活生物质比死生物质表现更优。对蜡样芽孢杆菌S5的耐镉基因分析确定了与耐镉相关且参与ATP泵机制的ATPase基因。傅里叶变换红外光谱（FTIR）显示原始生物质上存在氨基、羧基和羟基基团，并表明镉离子去除能力与菌株结构有关。基于对实验数据拟合的伪二级动力学模型，蜡样芽孢杆菌S5菌株在活孢子生物质中的最大吸附容量为70.16 mg/g（干重）。朗缪尔（Langmuir）和朗缪尔-弗伦德利希（Langmuir-Freundlich）等温吸附模型很好地拟合了镉离子吸附数据，动力学曲线表明吸附速率为二级。对于1 - 109 mg/L的Cd2+浓度，使用约3.48 - 10.3 g/L的蜡样芽孢杆菌S5菌株活性孢子生物质可实现良好的去除效率（>80%）。耐镉细菌活性炭固定柱在处理镉污染水时可使用更长时间，且比对照柱表现出更高的处理效果。此外，使用小鼠进行的毒性评估表明，蜡样芽孢杆菌S5菌株的生物质及其发酵产物无毒。因此，分离出的蜡样芽孢杆菌S5菌株可被视为一种替代生物吸附剂，用于应对严重镉污染的应急响应以及微量镉污染的常规处理。
