Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, China.
Laboratory for Marine Biology and Biotechnology, Qingdao Pilot National Laboratory for Marine Science and Technology, Qingdao, China.
Genome Biol Evol. 2021 Aug 3;13(8). doi: 10.1093/gbe/evab148.
Microbial strains with high genomic stability are particularly sought after for testing the quality of commercial microbiological products, such as biological media and antibiotics. Yet, using mutation-accumulation experiments and de novo assembled complete genomes based on Nanopore long-read sequencing, we find that the widely used quality-control strain Shewanella putrefaciens ATCC-8071, also a facultative pathogen, is a hypermutator, with a base-pair substitution mutation rate of 2.42 × 10-8 per nucleotide site per cell division, ∼146-fold greater than that of the wild-type strain CGMCC-1.6515. Using complementation experiments, we confirm that mutL dysfunction, which was a recent evolutionary event, is the cause for the high mutation rate of ATCC-8071. Further analyses also give insight into possible relationships between mutation and genome evolution in this important bacterium. This discovery of a well-known strain being a hypermutator necessitates screening the mutation rate of bacterial strains before any quality control or experiments.
具有高基因组稳定性的微生物菌株特别受到关注，可用于测试商业微生物产品（如生物培养基和抗生素）的质量。然而，我们通过突变积累实验和基于纳米孔长读测序从头组装的完整基因组发现，广泛用于质量控制的兼性病原体希瓦氏菌 Shewanella putrefaciens ATCC-8071 也是一个超突变体，其碱基对替换突变率为每细胞分裂每核苷酸位点 2.42×10-8，比野生型菌株 CGMCC-1.6515 高约 146 倍。通过互补实验，我们证实了 mutL 功能障碍是最近发生的进化事件，这是 ATCC-8071 高突变率的原因。进一步的分析还深入了解了在这个重要细菌中突变和基因组进化之间可能存在的关系。这一发现表明，一个著名的菌株是一个超突变体，这就需要在进行任何质量控制或实验之前，筛选细菌菌株的突变率。
