The Effect of ARTP Mutation on the Degradation Capacity of Citrobacter sp. D03.

To address the issues of low degradation efficiency in anaerobic bacteria targeting microcystin-LR (MC-LR) and the limitations of traditional genetic modification methods, this study applied ARTP mutagenesis technology for the first time to genetically engineer anaerobic MC-LR-degrading bacteria using the Citrobacter sp. D03 isolated from Lake Taihu sediments as the parental strain. Through three rounds of ARTP-induced mutagenesis and directed screening, a highly efficient mutant, C29, was obtained. The results indicate that the optimal mutagenesis conditions are 60 s, with a lethality rate of 90.15%; the anaerobic degradation efficiency of MC-LR by mutant strain C29 was 14% higher than that of the wild-type strain, and the genetic efficiency remained stable after consecutive passages. Whole-genome resequencing of the new strain C29 revealed 10 mutation sites, involving key genes such as toxD, cheA, murI, and mobB. qRT-PCR validation showed that the expression of genes related to sulfur metabolism, cell wall synthesis, molybdenum cofactor synthesis, and environmental adaptation was significantly upregulated. The study confirms that ARTP mutagenesis can effectively enhance the degradation capacity of anaerobic degrading bacteria toward MC-LR through polygenic synergistic regulation, providing both microbial resources and a theoretical basis for in situ anaerobic bioremediation of MC-LR pollution in eutrophic water bodies.