Transcriptome analysis of cadmium and mercury tolerant rhizobia and the impacts of tolerance on symbiosis with legumes

We have measured cadmium (Cd) and mercury (Hg) tolerance in a collection of Sinorhizobium medicae (recently changed to Ensifer medicae) and Rhizobium leguminosarum from the Almaden mine region in Central Spain. We have assembled and annotated the genomes of 16 strains from this collection using PacBio sequencing. Transcriptomics analysis was conducted on Cd and Hg tolerant and susceptible E. medicae strains to identify genome wide and single gene responses to these metals. The strains Amp08 and SMp01 both have a mercury reductase operon, which is not commonly found in alpha-proteobacteria.

本研究针对采自西班牙中部阿尔马登矿区的一组Sinorhizobium medicae（现已更名为Ensifer medicae）与豌豆根瘤菌（Rhizobium leguminosarum）菌株，测定了其对镉（Cd）与汞（Hg）的耐受性。本研究采用PacBio测序技术，对该菌株库中的16株菌完成了基因组组装与注释工作。针对镉、汞耐受型及敏感型的E. medicae菌株，本研究开展了转录组学分析，以解析其在全基因组水平与单基因层面对这两种金属的转录应答特征。菌株Amp08与SMp01均携带汞还原酶操纵子，这类操纵子在α-变形菌门（Alphaproteobacteria）中较为罕见。