| 摘要: |
| 【目的】对1株镉耐受性较强的弯孢属真菌C12进行分类鉴定，评估其对重金属镉的耐受能力，并初步分析和探讨其相关的镉耐性机制，为揭示真菌的重金属抗性机制及其在重金属污染治理中的应用提供依据。【方法】利用形态和分子生物学相结合的方法对菌株C12进行分类鉴定，采用固体和液体2种培养方法研究不同Cd2+质量浓度（0,20,40,80,160,320 mg/L）下菌株C12的生长状况，比较不同Cd2+质量浓度下菌株C12培养液中pH值和有机酸含量以及菌丝内谷胱甘肽（GSH）和丙二醛（MDA）含量的变化。【结果】菌株C12被鉴定为津田弯孢（Curvularia tsudae）；该菌在Cd2+质量浓度高达320 mg/L时仍有菌丝生长，菌丝体干质量在固体培养时随Cd2+质量浓度的升高先增加后降低，在Cd2+质量浓度为20 mg/L时达到最大（P<0.05），而液体培养时却随Cd2+质量浓度的升高逐渐降低（P<0.05）；培养液中柠檬酸和苹果酸的含量较高，琥珀酸仅在高Cd2+质量浓度（80~320 mg/L）时才会产生，未检测到草酸和酒石酸；随Cd2+质量浓度的升高，柠檬酸、苹果酸、乙酸和琥珀酸质量浓度以及菌丝内的GSH含量均先增加后降低，且在160 mg/L时达到最大（P<0.05），而培养液的pH值并无显著变化（P＞0.05），但均显著低于不加镉的对照（P<0.05）；菌丝内的MDA含量则随Cd2+质量浓度的升高先增加再降低后又升高，但差异并不显著（P＞0.05）。【结论】津田弯孢C12具有较高的镉耐受性，且液体培养条件下菌丝生长和镉耐受性明显优于固体培养，GSH和有机酸（柠檬酸、苹果酸和琥珀酸）的大量积累可能是其减轻镉毒害、提高镉耐受性的潜在机制之一。 |
| 关键词: 津田弯孢 镉耐受性 有机酸 谷胱甘肽 |
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| 基金项目:国家自然科学基金项目（31300543）；西北农林科技大学基本科研创新一般项目（2452013QN108，2452015343）；西北农林科技大学引进人才科研启动费项目（Z111021204）；陕西省专项配套经费项目 |
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| The identification and study on Cd tolerance of C12,a fungus which shows high tolerance to Cd |
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CHU Wenhui,XIE Qingzhe,YANG Chao,et al
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| Abstract: |
| 【Objective】In this study,one isolate of Curvularia sp.C12 which showed high tolerance ability to heavy metal cadmium was identified as Curvularia tsudae,and then the related tolerance mechanism was preliminarily analyzed and discussed. The results could provide the foundation for revealing the mechanism of fungal resistance to heavy metal,and for the application of fungi to control heavy metal pollution.【Method】The taxonomic status of isolate C12 was identified based on its morphological and molecular characteristics.Its tolerance ability to cadmium was assessed both in solid and liquid culture condition with different mass concentrations of Cd2+ (0,20,40,80,160,320 mg/L).pH value and organic acids contents,as well as glutathione (GSH) and malondialdehyde (MDA) contents in the fungal mycelia were measured and compared under different mass concentrations of Cd2+ in liquid culture condition.【Result】Isolate C12 was identified as Curvularia tsudae,and it could grow under 320 mg/L Cd2+.Along with the increase of Cd2+ mass concentrations,the mycelia dry weight of C.tsudae C12 was increased firstly and then decreased on solid culture condition,and reached the maximum at 20 mg/L(P<0.05),but was gradually reduced in liquid culture condition(P<0.05).In liquid culture condition,oxalic acid and tartaric acid did not be detected,while citric acid and malic acid content were relatively high,and succinic acid was only produced under high concentrations of Cd2+ (80-320 mg/L).With the increase of Cd2+ mass concentrations,the content of citric acid,malic acid,acetic acid and succinic acid,as well as GSH content in mycelia were increased firstly and then decreased,and reached the maximum at 160 mg/L (P<0.05);while MDA content in mycelia was increased firstly,then decreased and later rose again,but did not show significant difference (P＞0.05).pH values were significant lower than that of control (without cadmium) (P<0.05),however,did not change significantly (P＞0.05)along with the increase of Cd2+ mass concentrations.【Conclusion】Curvularia tsudae C12 showed high cadmium tolerance,and its growth and cadmium tolerance were obviously better under liquid culture condition.The accumulation of GSH and organic acids (especially citric acid,malic acid and succinic acid) maybe one of the underlying mechanisms for C.tsudae C12 to reduce the damage of cadmium and to improve its cadmium tolerance. |
| Key words: Curvularia tsudae Cadmium tolerance organic acid Glutathione |
