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Biological characteristics of Aspergillus tubingensis and its fixation to Pb²⁺

基金项目：国家重点基础研究发展计划(973)项目(No.2014CB846003);国家自然科学基金重点项目(No.41230103);国家地质调查项目(No.1212011120284)

摘要：从铅锌矿土壤中分离筛选出一株真菌LYF12(KJ569519),对其菌落、菌丝、分生孢子、生理生化特征、18S rRNA分子特征以及其对生存环境中Pb²⁺的固定作用等进行了实验研究.结果表明,菌株LYF12为塔宾曲霉(Aspergillus tubingensis),对Pb²⁺耐受浓度高达6 mmol·L^-1.TEM研究结果表明,菌株LYF12可以将Pb²⁺转移到细胞内,并以含铅矿物集合体的形式将Pb²⁺固定于细胞内部.当 Pb²⁺浓度低于4 mmol·L^-1时,LYF12对 Pb²⁺的固定率高达99%以上;当 Pb²⁺浓度为6 mmol·L^-1时,菌株对Pb²⁺的固定率也可达到81%.另外,又通过实验研究对比了不同能量供应水平下,LYF12对Pb²⁺吸附率的变化.结果表明,LYF12对Pb²⁺的吸附与能量供应水平密切相关,并由此推断:Pb²⁺跨过LYF12细胞膜进入细胞的方式可能是主动运输.

Abstract：The fungus LYF12 (KJ569519) was isolated from the soil around a lead-zinc ore deposit. Its microscopic structures, including colonies, hyphae, conidium, physiological and biochemical characteristics, and phylogenetic features such as 18S rRNA sequences, were systematically studied. The ability of LYF12 to fix Pb²⁺ was investigated. The results indicated that the strain LYF12 is Aspergillus tubingensis and sustained with Pb²⁺ concentration up to 6 mmol·L^-1. The fixation ratios of Pb²⁺ by LYF12 were directly related to the initial concentration of Pb²⁺. When the concentration of Pb²⁺ was lower than 4 mmol·L^-1, 99% of Pb²⁺ was fixed by LYF12, whereas the ratio dropped to 81% when the Pb²⁺ concentration was 6 mmol·L^-1. Transmission electron microscope (TEM) images of LYF12 after reactions with Pb²⁺ showed that aggregates of lead-bearing minerals were observed inside the cells. In addition, the fixation ratios of Pb²⁺ by LYF12 under anaerobic conditions, aerobic conditions, and in the presence of glucose, were compared. The results showed that higher level of energy metabolism resulted in higher fixation ratio. It implied that the transmembrane transport of Pb²⁺ in LYF12 might be an active transport.

Key words：Aspergillus tubingensis lead ion fixation biological characteristics active transport