Microbial arsenic transformation is important in As biogeochemical cycles in the environment. In this study, a new As-resistant bacterial strain Leclercia adecarboxylata As3-1 was isolated and its associated mechanisms in As resistance and detoxification were evaluated based on genome sequencing and gene annotations. After subjecting strain As3-1 to media containing arsenate (AsV), AsV reduction occurred and an AsV-enhanced bacterial growth was observed. Strain As3-1 lacked arsenite (AsIII) oxidation ability and displayed lower AsIII resistance than AsV, probably due to its higher AsIII accumulation. Polymerase chain reaction and phylogenetic analysis showed that strain As3-1 harbored a typical AsV reductase gene (arsC) on the plasmids. Genome sequencing and gene annotations identified four operons phoUpstBACS, arsHRBC, arsCRDABC and ttrRSBCA, with 8 additional genes outside the operons that might have involved in As resistance and detoxification in strain As3-1. These included 5 arsC genes explaining why strain As3-1 tolerated high AsV concentrations. Besides ArsC, TtrB, TtrC and TtrA proteins could also be involved in AsV reduction and consequent energy acquisition for bacterial growth. Our data provided a new example of diverse As-regulating systems and AsV-enhanced growth without ArrA in bacteria. The information helps to understand the role of As in selecting microbial systems that can transform and utilize As.

微生物砷的转化对于环境中的生物地球化学循环很重要。在这项研究中，分离出了一种新的抗As抗性菌株Leclercia adecarboxylata As3-1，并基于基因组测序和基因注释评估了其抗As和解毒的相关机制。将菌株As3-1置于含砷酸盐（AsV）的培养基中后，AsV降低，并且观察到AsV增强的细菌生长。As3-1菌株缺乏砷（AsIII）的氧化能力，并且比AsV表现出较低的AsIII抵抗力，这可能是由于其较高的AsIII积累。聚合酶链反应和系统发育分析表明，菌株As3-1带有一个典型的AsV还原酶基因（arsC。）。基因组测序和基因注释识别了四个操纵子phoUpstBACS，arsHRBC，arsCRDABC和ttrRSBCA，另外8个操纵子之外的基因可能与As3-1菌株的As抗性和解毒有关。这些包括5个arsC基因，解释了为什么As3-1菌株能够耐受高AsV浓度。除ArsC外，TtrB，TtrC和TtrA蛋白也可能参与AsV的减少并因此获得了细菌生长所需的能量。我们的数据为细菌中无ArrA的多种As调节系统和AsV增强的生长提供了新的例子。这些信息有助于了解砷在选择可以转化和利用砷的微生物系统中的作用。