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Abstract：
Significant microbial removal of highly chlorinated polychlorinated biphenyls (PCBs) requires the cooperation of anaerobic and aerobic bacteria. During the sequencing process of anaerobic dechlorination and aerobic degradation of PCBs, aerobic degrading bacteria have to undergo anaerobic stress. However, the survival strategy of aerobic degrading bacteria under anaerobic condition is not well-understood. In this study, the culturable cells of Rhodococcus biphenylivorans TG9 decreased from 108 CFU/mL to values below the detection limit after 60 days of anaerobic stress while the viable cells remained 105-106 cells/mL, indicating that anaerobic condition induced TG9 entering into the viable but nonculturable (VBNC) state. Cell resuscitation was observed when oxygen was supplied further confirming the VBNC state of TG9. The results of single-cell Raman spectroscopy combined with heavy water indicated the significant decrease of metabolic activity after TG9 entering into the VBNC state. Additionally, the degradation ability of TG9 in the VBNC state was also significantly reduced, while it recovered after resuscitation. Our research proved that entering into the VBNC state is a survival strategy of TG9 under anaerobic conditions, and the limited culturability and degrading capacity could be overcome by resuscitation. The present study provides new insights for improving the remediation efficiency of PCBs contamination.
摘要：
高度氯化的多氯联苯（PCB）的大量微生物去除需要厌氧和好氧细菌的合作。在多氯联苯厌氧脱氯和好氧降解的测序过程中，需氧降解细菌必须经历厌氧应激。然而,需氧降解菌在厌氧条件下的生存策略尚不清楚。在这项研究中,在60天的厌氧应激后，联苯红球菌TG9的可培养细胞从108CFU/mL下降到低于检测极限的值，而活细胞保持105-106细胞/mL，表明厌氧条件诱导TG9进入可行但不可培养(VBNC)状态。当供应氧气时观察到细胞复苏,进一步证实TG9的VBNC状态。单细胞拉曼光谱结合重水的结果表明，TG9进入VBNC状态后，代谢活性显着降低。此外,TG9在VBNC状态下的降解能力也显著降低,复苏后恢复了。我们的研究证明，进入VBNC状态是TG9在厌氧条件下的生存策略，有限的可培养性和退化能力可以通过复苏来克服。本研究为提高多氯联苯污染的修复效率提供了新的见解。
