ABSTRACT

Seven chromate-reducing yeasts isolated from Antarctic soils (with no history of Cr(VI) contamination) were evaluated as promising candidates for alleviating Cr(VI)-contamination. These yeast species have not been extensively studied regarding Cr(VI) tolerance and reduction abilities. Based on their tolerance (up to 2 mM) and ability to remove Cr(VI) from culture media, two representative isolates of Candida sake #14 and Debaryomyces hansenii #35 were chosen. The resistant yeasts were cultivated in YM medium plus 1 mM Cr(VI) at 25°C, causing a removal of ∼90 and ∼70% hexavalent chromium before reaching 96 h of culture according to growth curves of C. sake #14 and D. hansenii #35, respectively. Cr(VI) removal kinetic analysis indicated that both isolates removed Cr(VI) by reduction to Cr(III), and incorporated a small portion into the biomass. Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDX) confirms the biosorption process, indicating the existence of a complex remediation mechanism. In conclusion, Antarctica is an extreme environment with a potential to discover promising new candidates for the removal of Cr(VI). These results are interesting from a biotechnological point of view since psychrotolerant yeasts could be involved in the design of a profitable technology for the elimination of the toxic form of Cr.

摘要

从南极土壤中分离出的七种铬酸盐还原酵母（没有 Cr(VI) 污染的历史）被评估为减轻 Cr(VI) 污染的有希望的候选者。这些酵母种类尚未就 Cr(VI) 耐受性和还原能力进行广泛研究。基于它们的耐受性（高达 2 mM）和从培养基中去除 Cr(VI) 的能力，选择了清酒念珠菌#14 和汉森德巴利菌#35 的两个代表性分离株。根据清酒#14 和D的生长曲线，抗性酵母在 YM 培养基和 1 mM Cr(VI) 中于 25°C 培养，在达到 96 小时培养之前导致去除 ~90% 和 ~70% 六价铬汉森尼#35，分别。Cr(VI) 去除动力学分析表明，两种分离物均通过还原为 Cr(III) 去除 Cr(VI)，并将一小部分结合到生物质中。扫描电子显微镜-能量色散X射线光谱（SEM-EDX）证实了生物吸附过程，表明存在复杂的修复机制。总之，南极洲是一个极端环境，有可能发现有希望的去除 Cr(VI) 的新候选者。从生物技术的角度来看，这些结果很有趣，因为耐冷酵母可以参与设计一种用于消除有毒形式 Cr 的有利可图的技术。