Liu Yuanyuan, Yang Hongying, Zhang Xian, Xiao Yunhua, Guo Xue, Liu Xueduan
School of Materials and Metallurgy, Northeastern University, Shenyang, China; CNMC Luanshya Copper Mines Plc. (CLM), Luanshya, Zambia.
School of Materials and Metallurgy, Northeastern University, Shenyang, China.
Biomed Res Int. 2016;2016:8137012. doi: 10.1155/2016/8137012. Epub 2016 Apr 28.
Although reduced inorganic sulfur compound (RISC) oxidation in many chemolithoautotrophic sulfur oxidizers has been investigated in recent years, there is little information about RISC oxidation in heterotrophic acidophiles. In this study, Acidicaldus sp. strain DX-1, a heterotrophic sulfur-oxidizing acidophile, was isolated. Its genome was sequenced and then used for comparative genomics. Furthermore, real-time quantitative PCR was performed to identify the expression of genes involved in the RISC oxidation. Gene encoding thiosulfate: quinone oxidoreductase was present in Acidicaldus sp. strain DX-1, while no candidate genes with significant similarity to tetrathionate hydrolase were found. Additionally, there were genes encoding heterodisulfide reductase complex, which was proposed to play a crucial role in oxidizing cytoplasmic sulfur. Like many heterotrophic sulfur oxidizers, Acidicaldus sp. strain DX-1 had no genes encoding enzymes essential for the direct oxidation of sulfite. An indirect oxidation of sulfite via adenosine-5'-phosphosulfate was proposed in Acidicaldus strain DX-1. However, compared to other closely related bacteria Acidiphilium cryptum and Acidiphilium multivorum, which harbored the genes encoding Sox system, almost all of these genes were not detected in Acidicaldus sp. strain DX-1. This study might provide some references for the future study of RISC oxidation in heterotrophic sulfur-oxidizing acidophiles.
尽管近年来对许多化能自养型硫氧化菌中还原态无机硫化合物（RISC）的氧化进行了研究，但关于异养嗜酸菌中RISC氧化的信息却很少。在本研究中，分离出了一株异养硫氧化嗜酸菌——酸热硫化叶菌属菌株DX-1。对其基因组进行了测序，然后用于比较基因组学研究。此外，还进行了实时定量PCR以鉴定参与RISC氧化的基因的表达。酸热硫化叶菌属菌株DX-1中存在编码硫代硫酸盐：醌氧化还原酶的基因，而未发现与连四硫酸盐水解酶具有显著相似性的候选基因。此外，还存在编码异二硫还原酶复合物的基因，该复合物被认为在氧化细胞质硫中起关键作用。与许多异养硫氧化菌一样，酸热硫化叶菌属菌株DX-1没有编码亚硫酸盐直接氧化所必需酶的基因。酸热硫化叶菌属菌株DX-1中提出了通过腺苷-5'-磷酸硫酸酯对亚硫酸盐进行间接氧化的途径。然而，与其他携带编码Sox系统基因的密切相关细菌嗜酸栖热嗜酸菌和多嗜酸栖热嗜酸菌相比，在酸热硫化叶菌属菌株DX-1中几乎未检测到所有这些基因。本研究可能为未来异养硫氧化嗜酸菌中RISC氧化的研究提供一些参考。
