Microbial precipitation of Pb(II) with wild strains of Paraclostridium bifermentans and Klebsiella pneumoniae isolated from an industrially obtained microbial consortium

Supplementary data for a paper titled 'Microbial precipitation of Pb(II) with wild strains of Paraclostridium bifermentans and Klebsiella pneumoniae isolated from an industrially obtained microbial consortium' published on International Journal of Molecular Sciences 2022, 23(20),12255.  
The study focused on the establishment of the microbial precipitation abilities of bacterial strains that were isolated from an industrially obtained Pb(II)-resistant microbial consortium. Previousresearch has demonstrated the effectiveness of the consortium on the bioprecipitation and adsorptionof Pb(II) from solution. The bioremediation of Pb(II) using microbial precipitation provides an alternative option for Pb(II) removal from wastewater. Both strains, Klebsiella pneumoniae and Paraclostridium bifermentans, were successfully isolated from the consortium obtained from a battery recycling plant in South Africa. 
The experiments were conducted over both 30 h and 5 d, providing insight into the short- and long-term precipitation abilities of the bacteria. Various initial concentrations of Pb(II) were investigated, and it was found that P. bifermentans was able to remove 83.8% of Pb(II) from solution with an initial Pb(II) concentration of 80 mg L−1, while K. pneumoniae was able to remove 100% of Pb(II) with the same initial Pb(II) concentration after approximately 5 d. With the same initial Pb(II) concentration, P. bifermentans was able to remove 86.1% of Pb(II) from solution, and K. pneumoniae was able to remove 91.1% of Pb(II) from solution after 30 h. The identities of the precipitates obtained for each strain vary, with PbS and Pb0 being the main species precipitated by P. bifermentans and PbO with either PbCl or Pb3(PO4)2 precipitated by K. pneumoniae. Various factors were investigated in each experiment, such as metabolic activity, nitrate concentration, residual Pb(II) concentration, extracellular and intracellular Pb(II) concentration and the precipitate identity. These factors provide a greater understanding of the mechanisms utilised by the bacteria in the bioprecipitation and adsorption of Pb(II). These results can be used as a step towards applying the process on an industrial scale.

本研究针对从工业获取的含铅(II)抗性微生物共生体中分离得到的细菌菌株的微生物沉淀能力进行探讨。前期研究已证实该共生体在从溶液中生物沉淀和吸附铅(II)方面的有效性。利用微生物沉淀技术进行铅(II)的生物修复，为废水中的铅(II)去除提供了一种替代方案。两种菌株，肺炎克雷伯菌（Klebsiella pneumoniae）和双歧梭菌（Paraclostridium bifermentans），均成功从南非某电池回收厂获取的共生体中分离得到。实验分别在30小时和5天内进行，以洞察细菌的短期和长期沉淀能力。研究了不同的铅(II)初始浓度，发现双歧梭菌在初始铅(II)浓度为80 mg L−1的条件下，能够从溶液中去除83.8%的铅(II)，而肺炎克雷伯菌在大约5天后，在同等的初始铅(II)浓度下，能够去除100%的铅(II)。在相同的初始铅(II)浓度下，双歧梭菌能够在30小时内从溶液中去除86.1%的铅(II)，肺炎克雷伯菌则能去除91.1%。每种菌株所获得的沉淀物身份各异，双歧梭菌主要通过沉淀PbS和Pb0，而肺炎克雷伯菌则通过沉淀PbO、PbCl或Pb3(PO4)2。每个实验中均研究了多种因素，例如代谢活性、硝酸盐浓度、残余铅(II)浓度、细胞外和细胞内铅(II)浓度以及沉淀物的身份。这些因素有助于深入理解细菌在生物沉淀和吸附铅(II)过程中所利用的机制。这些研究结果可作为向工业规模应用该过程迈进的一步。