耐錳細菌鑒定與錳脅迫下的生理響應

摘要：為了探究細菌對錳的適應機制，從松桃的錳冶煉區寨英鎮采集的土樣中分離得到7株耐錳能力達到1800mg/L的細菌，其中S7和S16兩株菌對錳的耐受能力高達2200mg/L。形態學、生理生化和16S rDNA 基因測序等分析結果表明，這些菌分屬于根癌土壤桿菌、沙福芽孢桿菌、根瘤菌屬和氧化節桿菌。在錳脅迫條件下，測定菌株S7的生長曲線、超氧化物歧化酶（Superoxide Dismutase，SOD）、過氧化氫酶（Catalase，CAT）活性和電導率。結果表明：在無錳條件下，細菌的生長速度很快，14～18小時后就進入穩定期，在錳脅迫條件下，菌株的生長速度明顯減慢，S7菌株的SOD、CAT酶活性在10～18小時時升高，但電導率變化不大。推測耐錳細菌可能通過上調氧化還原酶的活性適應錳脅迫。這對揭示細菌耐受錳的生理機制和錳污染的微生物修復技術奠定理論基礎。

關鍵詞：錳抗性細菌；超氧化物歧化酶；過氧化氫酶；錳適應

中圖分類號：Q93-3

文獻標識碼：A

文章編號：1008-0457（2017）03-0023-06國際DOI編碼：10.15958/j.cnki.sdnyswxb.2017.03.004

Abstract：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 ProvinceThese bacteria could survive in medium with Mn2+ concentration of more than 1800mg/L，with two strainsS7 and S16 tolerance of Mn2+ concentration up to 2200mg/LThese strains were classified into Agrobacterium tumefaciens，Bacillus safensis，Rhizobium spand Arthrobacter oxydans based on the morphology，physiology，biochemical characters and 16S rDNA gene sequencesUnder the condition of manganese stress，the growth curves，the activities of superoxide dismutase（SOD），catalase（CAT） and the conductivity of strain S7 were determinedThe results showed that strain S7 bacteria grew very fast under no Mn stress conditions and reached steady growth period after 14 to 18 hoursThe growth of S7 was clearly slowed down under the Mn stress conditionsThe enzyme activities of SOD and CAT reached their peaks after 1018 hours while the conductivity was unchangedIt is speculated that manganeseresistant bacteria may adapt to manganese stress by upregulating the activity of oxidoreductaseThis would provide the theoretical basis for revealing the physiological mechanism of bacteria tolerance to manganese stress and microbial remediation of manganese pollution

Key words：manganeseresistant bacteria；superoxide dismutase；catalase；manganese adaptation

貴州省松桃苗族自治縣的錳礦資源豐富，是我國三大錳礦基地之一，與相鄰的湖南花垣、重慶秀山形成我國有名的“錳三角”[1]。隨著錳礦的開采、冶煉，化肥制造和醫藥生產以及工業廢水排放等日益增多，水體和土壤中的錳含量日趨增多[2-4]，“錳三角”地區地下水的錳含量達到832±034mg/L，遠遠超過國標飲用水標準01mg/L[《生活飲用水水質衛生規范》（GB5749-2006）]，超標率高達798%。由于重金屬的不可降解性，土壤中的重金屬通過地下水和食物鏈可長期威脅人類和野生動物的安全，因此錳是礦區周邊廣泛存在的環境污染物[5]。……