1株好氧反硝化菌的分离鉴定及反硝化特性研究

Identification and Denitrification Characteristics of an Aerobic Denitrifier

经BTB培养基初筛和反硝化活力定量测定,从草鱼养殖池水中分离得到1株具有较高脱氮效率的好氧反硝化菌F1.通过形态观察、生理生化特性及16S rDNA同源性分析,确定该菌株为施氏假单胞菌(Pseudomonas stutzeri).反硝化特性研究结果表明,该菌脱氮的最适碳源为乙酸钠、柠檬酸钠、葡萄糖和蔗糖,对硝酸盐的去除率均达到100%;当C/N比不低于10时,该菌的脱氮率可达到96%以上,且无亚硝酸盐的积累;最适生长和最佳脱氮的温度和pH值分别为30℃和7.0;当DO值为3.4～7.2 mg/L时,菌株24 h的脱氮率均可达到85%以上;以NaNO3或NaNO2为氮源时,菌株的反硝化过程主要发生在对数生长期,32 h的脱氮率分别达到92.51%和82.73%.结果提示,菌株F1能直接以NO 3-或NO 2-为底物进行反硝化,并能耐受较高的溶解氧,可以作为调节养殖水体水质的候选菌株.

An aerobic denitrifier named F1 was isolated from grass fish pond water by BTB culture medium preliminary screening and denitrification activity analysis.The isolate was identified as Pseudomonas stutzeri through morphological feature,biochemical characteristics and 16S rDNA sequence analysis.Further studies showed that the optimal carbon resources for F1 denitrification were sodium acetate,sodium citrate,glucose and sucrose,with which the nitrate removal rate could reach 100%.When C/N ratio was above 10,the nitrogen removal rate of strain F1 was more than 96% and no nitrite was accumulated.The optimum condition for F1 growth and aerobic denitrification was temperature 30℃ and pH 7.0.The F1 could tolerate dissolved oxygen level of 3.4-7.2 mg/L,and its nitrogen removal rate was more than 85% in 24 hours.Denitrification process of F1 mainly occurred in the exponential phase with NaNO3 or NaNO2 as nitrogen resource,and its denitrification rate reached 92.51% and 82.73%,respectively after 32 h of culture.These results suggest that strain F1 can denitrify NO-3 or NO-2 directly,and can tolerant a high dissolved oxygen level,and these characteristics make it a good candidate for aquaculture water quality treatment.