The aim of this study was to examine four strains of two yeast species in relation to their capability for assimilating alkanes in the presence of heavy metals (HMs). The four strains tested were Candida pseudoglaebosa ENCB-7 and Kodamaea ohmeri ENCB-8R, ENCB-23, and ENCB-VIK. Determination was made of the expression of CYP52 genes involved in alkane hydroxylation. When exposed to Cu2+ , Zn2+ , Pb2+ , Cd2+ , and As3+ at pH 3 and 5, all four strains could assimilate several n-alkanes having at least six carbon atoms. The three K. ohmeri strains could also utilize branched alkanes, cycloalkanes, and n-octanol as sole carbon sources. Kinetic assays demonstrated greater biomass production and specific growth of the yeasts exposed to long-chain n-alkanes. Fragments of paralogous CYP52 genes of C. pseudoglaebosa ENCB-7 and K. ohmeri ENCB-23 were amplified, sequenced, and phylogenetically evaluated. Reverse-transcription polymerase chain reaction revealed that n-nonane and n-decane induced to CpCYP52-G3, CpCYP52-G9, and CpCYP52-G10. KoCYP52-G3 was induced with n-decane and n-octanol. Also, CpCYP52-G3 and CpCYP52-G9 were induced by glucose. In conclusion, C. pseudoglaebosa and K. ohmeri were able to degrade several alkanes in the presence of HMs and under acidic conditions. These yeasts harbor paralogous alkane-induced CYP52 genes, which display different profiles of transcriptional expression.

中文翻译：

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拟釉假丝酵母和 Kodamaea ohmeri 能够在重金属存在的情况下降解烷烃


本研究的目的是检查两种酵母的四种菌株在重金属 (HM) 存在下同化烷烃的能力。测试的四种菌株是拟釉假丝酵母 ENCB-7 和 Kodamaea ohmeri ENCB-8R、ENCB-23 和 ENCB-VIK。测定了参与烷烃羟基化的CYP52基因的表达。当在 pH 3 和 5 下暴露于 Cu2+、Zn2+、Pb2+、Cd2+ 和 As3+ 时，所有四种菌株都可以同化几种具有至少 6 个碳原子的正烷烃。三种 K. ohmeri 菌株还可以利用支链烷烃、环烷烃和正辛醇作为唯一碳源。动力学测定表明，暴露于长链正烷烃的酵母具有更大的生物量产量和特定生长。对 C. pseudoglaebosa ENCB-7 和 K. ohmeri ENCB-23 的旁系同源 CYP52 基因片段进行了扩增、测序和系统发育评估。逆转录聚合酶链反应显示正壬烷和正癸烷诱导形成 CpCYP52-G3、CpCYP52-G9 和 CpCYP52-G10。 KoCYP52-G3用正癸烷和正辛醇诱导。此外，CpCYP52-G3和CpCYP52-G9由葡萄糖诱导。总之，在 HM 存在和酸性条件下，C. pseudoglaebosa 和 K. ohmeri 能够降解多种烷烃。这些酵母含有旁系同源烷烃诱导的 CYP52 基因，显示出不同的转录表达谱。