Adaptive laboratory evolution of Rhodococcus rhodochrous DSM6263 for chlorophenol degradation under hypersaline condition

Microbial Cell Factories

Research

Bo Yu¹  Yubin Xue¹  Juan An²  Jie Zheng²  Zhengzhi Zhang³ 

[1] CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China;CAS Key Laboratory of Microbial Physiological & Metabolic Engineering, State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, China;University of Chinese Academy of Sciences, 100049, Beijing, China;Linyi Municipal Ecology and Environment Bureau, 276000, Linyi, China;

关键词: Chlorophenols;    Rhodococcus rhodochrous;    Bioremediation;    Hypersaline;    Adaptive laboratory evolution;   

DOI  :  10.1186/s12934-023-02227-7

 received in 2023-08-29, accepted in 2023-10-08,  发布年份 2023

来源: Springer

【 摘 要 】

BackgroundNormally, a salt amount greater than 3.5% (w/v) is defined as hypersaline. Large amounts of hypersaline wastewater containing organic pollutants need to be treated before it can be discharged into the environment. The most critical aspect of the biological treatment of saline wastewater is the inhibitory/toxic effect exerted on bacterial metabolism by high salt concentrations. Although efforts have been dedicated to improving the performance through the use of salt-tolerant or halophilic bacteria, the diversities of the strains and the range of substrate spectrum remain limited, especially in chlorophenol wastewater treatment.ResultsIn this study, a salt-tolerant chlorophenol-degrading strain was generated from Rhodococcus rhodochrous DSM6263, an original aniline degrader, by adaptive laboratory evolution. The evolved strain R. rhodochrous CP-8 could tolerant 8% NaCl with 4-chlorophenol degradation capacity. The synonymous mutation in phosphodiesterase of strain CP-8 may retard the hydrolysis of cyclic adenosine monophosphate (cAMP), which is a key factor reported in the osmoregulation. The experimentally verified up-regulation of intracellular cAMP level in the evolved strain CP-8 contributes to the improvement of growth phenotype under high osmotic condition. Additionally, a point mutant of the catechol 1,2-dioxygenase, CatAN211S, was revealed to show the 1.9-fold increment on activity, which the mechanism was well explained by molecular docking analysis.ConclusionsThis study developed one chlorophenol-degrading strain with extraordinary capacity of salt tolerance, which showed great application potential in hypersaline chlorophenol wastewater treatment. The synonymous mutation in phosphodiesterase resulted in the change of intracellular cAMP concentration and then increase the osmotic tolerance in the evolved strain. The catechol 1,2-dioxygenase mutant with improved activity also facilitated chlorophenol removal since it is the key enzyme in the degradation pathway.

【 授权许可】

CC BY   
© BioMed Central Ltd., part of Springer Nature 2023

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