耐锰细菌鉴定与锰胁迫下的生理响应

为了探究细菌对锰的适应机制,从松桃的锰冶炼区寨英镇采集的土样中分离得到7株耐锰能力达到1 800mg/L的细菌,其中S7和S16两株菌对锰的耐受能力高达2 200 mg/L。形态学、生理生化和16S rDNA基因测序等分析结果表明,这些菌分属于根癌土壤杆菌、沙福芽孢杆菌、根瘤菌属和氧化节杆菌。在锰胁迫条件下,测定菌株S7的生长曲线、超氧化物歧化酶(Superoxide Dismutase,SOD)、过氧化氢酶(Catalase,CAT)活性和电导率。结果表明:在无锰条件下,细菌的生长速度很快,14~18小时后就进入稳定期,在锰胁迫条件下,菌株的生长速度明显减慢,S7菌株的SOD、CAT酶活性在10~18小时时升高,但电导率变化不大。推测耐锰细菌可能通过上调氧化还原酶的活性适应锰胁迫。这对揭示细菌耐受锰的生理机制和锰污染的微生物修复技术奠定理论基础。

Identification of Manganese-Resistant Bacteria and Their Physiological Response Under Manganese Stress

In order to explore the mechanism of the adaptation of bacteria to manganese,seven strains of bacteria were isolated from the soil samples collected from a manganese smelting area in Zhaiying town of Songtao County,Guizhou Province.These bacteria could survive in medium with Mn2+ concentration of more than 1800mg/L,with two strains-S7 and S16 tolerance of Mn2+ concentration up to 2200mg/L.These strains were classified into Agrobacterium tumefaciens,Bacillus safensis,Rhizobium sp.and Arthrobacter oxydans based on the morphology,physiology,biochemical characters and 16S rDNA gene sequences.Under the condition of manganese stress,the growth curves,the activities of superoxide dismutase(SOD),catalase(CAT) and the conductivity of strain S7 were determined.The results showed that strain S7 bacteria grew very fast under no Mn stress conditions and reached steady growth period after 14 to 18 hours.The growth of S7 was clearly slowed down under the Mn stress conditions.The enzyme activities of SOD and CAT reached their peaks after 10-18 hours while the conductivity was unchanged.It is speculated that manganese-resistant bacteria may adapt to manganese stress by up-regulating the activity of oxidoreductase.This would provide the theoretical basis for revealing the physiological mechanism of bacteria tolerance to manganese stress and microbial remediation of manganese pollution.