Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
College of Life Sciences, Nankai University, Tianjin 300071, China; State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300350, China.
J Hazard Mater. 2019 Mar 5;365:270-279. doi: 10.1016/j.jhazmat.2018.10.080. Epub 2018 Oct 29.
Two representative low nucleic acid-content (LNA) bacterial strains, Polynucleobacter sp. CB and Sphingopyxis sp. 15Y-HN, and two commonly used microbial indicators of drinking water disinfection efficiency, Escherichia coli and Pseudomonas aeruginosa, were used to investigate the effects of chlorine disinfection. LNA bacteria were found to be more tolerant than microbial indicator strains at the same free chlorine concentrations in batch experiments. Three-stage chlorination experiments were carried out for two strains (15Y-HN and E. coli K12) to compare their responses to long-term chlorine exposure. Results from the first stage (increasing chlorine exposure from 0.0 to 0.6 mg/L and 1.2 mg/L for strain K12 and strain 15Y-HN, respectively) showed the rate constants of 99% cell damage were 10-fold lower for strain 15Y-HN than for strain K12. A second regrowth stage at low free chlorine concentrations (<0.3 mg/L for 140 h) facilitated the regrowth of chlorine-resistant populations of strains 15Y-HN and K12 in the presence of assimilable organic carbon (AOC). In the third stage, during which bacteria were exposed to increasing chlorine from 0.0 to 0.5-0.6 mg/L, strain 15Y-HN was maintained at 80% and 10 cells/mL of intact cells whereas strain K12 was completely damaged. The overall results demonstrated that representative LNA bacteria exhibit strong resistance and resilience to chlorine under low AOC conditions, which should be taken into consideration in disinfection processes.
选取两种具有代表性的低核酸含量（LNA）细菌，即 Polynucleobacter sp. CB 和 Sphingopyxis sp. 15Y-HN，以及两种常用的饮用水消毒效率微生物指示剂，即大肠杆菌和铜绿假单胞菌，来研究氯消毒的效果。在批量实验中，发现 LNA 细菌在相同的游离氯浓度下比微生物指示剂菌株更能耐受。对两种菌株（15Y-HN 和大肠杆菌 K12）进行了三阶段氯化实验，以比较它们对长期氯暴露的反应。第一阶段（将氯暴露从 0.0 增加到 0.6 mg/L 和 1.2 mg/L，分别为 K12 和 15Y-HN 菌株）的结果表明，15Y-HN 菌株的 99%细胞损伤的速率常数比 K12 菌株低 10 倍。在低游离氯浓度（140 h 时<0.3 mg/L）的第二个再生长阶段，在可同化有机碳（AOC）存在的情况下，促进了 15Y-HN 和 K12 菌株的氯抗性种群的再生长。在第三阶段，当细菌从 0.0 增加到 0.5-0.6 mg/L 的氯时，15Y-HN 菌株保持 80%和 10 细胞/mL 的完整细胞，而 K12 菌株则完全受损。总体结果表明，代表性的 LNA 细菌在低 AOC 条件下对氯表现出很强的抗性和弹性，这在消毒过程中应加以考虑。
