高效好氧反硝化盖氏假单胞菌YZ-7的鉴定及其脱氮性能研究

Identification and denitrification performance of an efficient aerobic denitrification bacterium Pseudomonas gessardii YZ-7

  • 摘要: 【目的】筛选出高效好氧反硝化细菌,开发出适宜在虾塘应用且具有强脱氮能力的新菌株,以解决虾塘因氮素含量过高引起的水体富营养化等问题。【方法】采用稀释涂布法和Giltay鉴别培养基从稻虾养殖塘的污水污泥中分离筛选高效脱氮菌株,结合形态学特性、生理生化特征和16S rDNA序列分析对分离菌株进行鉴定;测定分离菌株在KNO3氮源条件下的脱氮效率,同时分析不同环境因子对分离菌株反硝化能力的影响,并通过模拟试验评价其在处理虾塘养殖废水时的反硝化性能。【结果】从稻虾养殖塘污水污泥中分离获得1株高效脱氮菌,经形态学特性、生理生化特征和16S rDNA序列分析鉴定为盖氏假单胞菌(Pseudomonas gessardii),命名为YZWF2207(简写为YZ-7)。以KNO3为唯一氮源时,菌株YZ-7经过6 h的迟缓期后进入对数生长阶段,且菌株YZ-7生长速率与含氮物质的去除速率密切相关。以柠檬酸钠为唯一碳源时,菌株YZ-7对硝态氮(NO3--N)的去除率为99.05%;碳氮比(C/N)范围为4.42~5.00时,菌株YZ-7具有较高的NO3--N去除率(99.71%~99.85%);菌株YZ-7的最高NO3--N去除率与生物量最大值并不同步,其更适宜生活在弱碱性(pH 7.0~8.0)环境中;菌株YZ-7的适宜环境温度为30℃,但在低温(15℃)下也能高效率完成反硝化过程,NO3--N去除率可达79.41%。菌株YZ-7对虾塘养殖废水中的NO3--N去除效果极显著(P<0.01),且积累的亚硝态氮(NO2--N)相对于对照组有明显下降趋势。【结论】从稻虾养殖塘污水污泥中分离获得1株反硝化能力强的盖氏假单胞菌(YZ-7),其实现最佳好氧反硝化性能的碳源为柠檬酸钠,C/N为4.42~5.00,pH为7.0~8.0,温度为30℃。菌株YZ-7在养殖废水处理方面具有较强的反硝化能力和竞争优势,作为好氧反硝化细菌在富氮养殖废水的脱氮生物产品研发中具有广阔应用前景。

     

    Abstract: 【Objective】 The efficient aerobic denitrification bacteria were screened to develop new strains with strong denitrification ability suitable for application in shrimp ponds, so as to solve the problem of eutrophication caused by excessive nitrogen content in shrimp ponds.【Method】 An efficient aerobic denitrification bacterium was isolated and screened from shrimp pond sewage sludge and water samples by diluted method in Giltay differential medium. Then it was identified by morphological characteristics, physiological and biochemical characteristics and 16S rDNA sequence analysis. Furthermore, the denitrification efficiency of the isolated strain under KNO3 as nitrogen source was determined, and the effects of different environmental conditions on denitrification performance of the isolated strain was analyzed. Finally, the denitrification ability of the strain in shrimp pond aquaculture waste water was evaluated by simulation test.【Result】 An efficient denitrification bacterium was isolated from shrimp pond sewage sludge and water samples. It was identified as Pseudomonas gessardii by morphological characteristics, physiological and biochemical characteristics and 16S rDNA sequence analysis, and named YZWF2207(YZ-7). When KNO3 was used as the sole nitrogen source, strain YZ-7 entered the logarithmic growth phase after a 6 h lag period, with the growth rate of the strain YZ-7 closely related to the removal rate of nitrogen-containing substances. When sodium citrate was used as the solecarbon source, the removal rate of nitrate nitrogen(NO3--N) was 99.05%. When the carbon/nitrogen ratio(C/N) ranged from 4.42 to 5.00, strain YZ-7 had relatively high NO3--N removal rate(99.71%-99.85%). The highest NO3--N removal rate of strain YZ-7 was not synchronized with the maximum biomass. And it was more suitable to living in weak alkaline environment(pH 7.0-8.0). The appropriate ambient temperature of strain YZ-7 was 30℃ though, the denitrification process could be completed efficiently at low temperature(15℃), and the NO3--N removal rate could reach 79.41%. Strain YZ-7 had extremely significant effect on NO 3--N removal from shrimp pond aquaculture wastewater(P<0.01), and the accumulated nitrite nitrogen(NO2--N) had obvious downward trend compared with the control group.【Conclusion】 An efficient aerobic denitrification bacterium P. gessardii(YZ-7) is isolated from shrimp pond sewage sludge and water samples. The optimum carbon source for aerobic denitrification performance is sodium citrate, with the C/N ratio of 4.42-5.00, pH of 7.0-8.0, and the temperature of 30℃. The strain YZ-7 has strong denitrification ability and competitiveness in aquaculture wastewater treatment. As an aerobic denitrification bacterium, it has broad application prospects in the research and development of denitrification biological products in nitrogen-rich aquaculture water.

     

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