College of Geography and Environmental Science, Zhejiang Normal University, Jinhua, 321004, China.
Department of Civil and Environmental Engineering, Shantou University, Shantou, Guangdong, 515063, China.
Chemosphere. 2019 Oct;232:76-86. doi: 10.1016/j.chemosphere.2019.05.195. Epub 2019 May 24.
The goal of this work was to investigate the genetics of an acidophilic phenol-degrading yeast strain using whole-genome sequencing (WGS), characterize the growth of the strain and phenol degradation capability as well as degradation pathway under extremely acidic conditions. The result showed that the strain ZM1 isolated from an acid mine drainage (AMD) belongs to basidiomycetous yeast Rhodotorula sp., which possesses some unique genes compared to other four closely related Rhodotorula species. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis suggested that ZM1 possessed the degradation potentials for aromatic compounds. ZM1 was acidophilic with the optimum growth at the initial pH of 3.0. It could adjust pH to desired levels probably by acid production during the cultivation. Notably, at pH 3.0, the strain ZM1 showed a high phenol-degrading capability that almost completely degraded 1100 mg/L of phenol in 120 h with the highest degradation rate of 0.074 g/(g cell dry weight h). Under the same pH, the strain could completely degrade 500 mg/L phenol within 48 h at NaCl concentration up to 10 g/L. The identification of the gene catA by the KEGG analysis, together with the presence of metabolic intermediate of cis, cis-muconic acid detected by gas chromatography-mass spectrometry, confirmed that the strain ZM1 degraded phenol via ortho-cleavage pathway. These findings suggest that the indigenous yeasts strain ZM1 could be exploited as an important member for in-situ biodegradation of aromatic compounds in the extremely acidic environments.
本工作旨在利用全基因组测序(WGS)研究一株嗜酸苯酚降解酵母的遗传学特性,表征该菌株在极端酸性条件下的生长特性和苯酚降解能力及降解途径。结果表明,从酸性矿山排水(AMD)中分离到的菌株 ZM1 属于担子菌酵母属 Rhodotorula sp.,与其他四种密切相关的 Rhodotorula 种相比,它具有一些独特的基因。京都基因与基因组百科全书(KEGG)分析表明,ZM1 具有降解芳香族化合物的潜力。ZM1 是嗜酸的,最适生长初始 pH 为 3.0。它可能通过在培养过程中产生酸来调节所需的 pH 值。值得注意的是,在 pH 3.0 时,该菌株 ZM1 表现出很高的苯酚降解能力,在 120 h 内几乎完全降解 1100mg/L 的苯酚,最高降解速率为 0.074g/(g 细胞干重 h)。在相同的 pH 值下,该菌株在 10g/L NaCl 浓度下可在 48h 内完全降解 500mg/L 的苯酚。KEGG 分析鉴定的 catA 基因,以及气相色谱-质谱检测到的顺式,顺式-粘康酸代谢中间产物的存在,证实了菌株 ZM1 通过邻位裂解途径降解苯酚。这些发现表明,土著酵母菌株 ZM1 可以作为极端酸性环境中芳香族化合物原位生物降解的重要成员。