Abstract

Twenty-four yeast isolates were obtained from radiation-polluted areas soils samples exposed to ⁶⁰Co-γ radiation at a dose of 10 kGy and identified as members of the genus Cryptococcus based on morphological and LSU rDNA D1/D2 domain sequence analysis. Further phylogenetic analysis showed that the isolates were clustered into 4 branches. The investigation of these yeast isolates revealed D₁₀ values for γ radiation of 5 (M2), 5 (M38), 6 (M22) and 7 kGy (M5) and a 4 × 10^–3% survival rate at a UV dosage of 200 J/m². Furthermore, the tolerance of M5 towards Zn²⁺ was as high as 1.700 mg/L. The isolate M5 was selected for further study, including the distribution of heavy metals within the cells by subcellular fractionation, expression of relevant genes involved in heavy metal resistance by qRT-PCR, and the removal rate by flame atomic absorption spectrometry (FAAS). The results revealed that almost 72.9% of the Zn²⁺ was absorbed by the cells and deposited mainly in the membrane fraction. Compared to normal conditions, all of the genes in M5 strain related to transport and regulation showed greater than 10.4-fold increases of expression levels upon exposure to heavy metal stress. In the presence of culture medium, a total of 86.5% of the initial concentration of Zn²⁺ was removed by the M5 strain exhibiting high removal efficiency and providing a potential of radiation-resistant platform strain for the bioremediation of heavy metals in polluted environments in the near future.

中文翻译：

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从辐射污染地区分离的抗辐射酵母的表征及其在生物修复中的潜在应用

摘要

从暴露于辐射污染地区的土壤样品得到二十四株酵母⁶⁰剂量10千戈瑞的共同γ辐射和鉴定为属的成员隐球菌基于形态学和LSU rDNA的D1 / D2区序列分析。进一步的系统发育分析表明，分离株聚集成4个分支。对这些酵母菌株的研究表明，在200紫外线剂量下，γ辐射的D ₁₀值为5（M2），5（M38），6（M22）和7 kGy（M5），存活率为4×10 ^–3％ J / m ²。此外，M5对Zn ²⁺的耐受性高达1.700 mg / L。选择了分离物M5进行进一步研究，包括通过亚细胞分馏在细胞内分布重金属，通过qRT-PCR表达与重金属抗性有关的相关基因以及通过火焰原子吸收光谱法（FAAS）去除率。结果表明，几乎72.9％的Zn ²⁺被细胞吸收并主要沉积在膜部分中。与正常条件相比，M5品系中所有与运输和调控有关的基因在重金属胁迫下均表现出大于10.4倍的表达水平增加。在培养基中，Zn ²⁺的初始浓度总计为86.5％ 被M5菌株去除的M5菌株具有很高的去除效率，并在不久的将来为污染环境中的重金属的生物修复提供了抗辐射平台菌株的潜力。