一株耐盐脱硫脱氮施氏假单胞菌的筛选及其对硫氮污染的控制

Screening of a halotolerant desulfurizing and denitrifying bacterium Stutzerimonas stuzeri with control effect on sulfide and nitrate pollution

摘要:

目的 为更好地控制海水养殖尾水中的硝酸盐和硫化物污染，降低其排放对生态环境造成的风险，本研究旨在筛选出能够进行同步脱硫脱氮的耐盐菌株，并研究其生长特性。方法 采用稀释涂布-叠皿夹法分离筛选耐盐脱硫脱氮菌株，并通过观察形态和16S rRNA基因序列对比加以鉴定。以单因素试验为基础，分析影响脱硫脱氮效果的关键因子(碳源、温度、盐度、pH值和接种比例)，并探究菌株对硫化物(S^2-)的耐受阈值。结果 从硫基混养反硝化污泥中筛选出一株施氏假单胞菌(Stutzerimonas stutzeri) D1-2，该菌株能够在有机碳源条件下，同步去除环境中的硫化物和硝酸盐。菌株D1-2以乳酸钠为最优碳源，最佳接种比例为1.5%，在温度15-35 ℃、盐度10‰-50‰、初始pH值6.0-8.0的条件下，对硫代硫酸盐和硝态氮的去除率均大于80%。当S^2-初始浓度为50 mg/L时，菌株D1-2表现出显著的耐受性，对S^2-和NO₃^--N的去除率分别达到97.91%和94.67%。结论 本研究关于S. stutzeri能够进行异养硫氧化的相关报道，表明耐盐菌株S. stutzeri D1-2具有高效的同步脱硫脱氮效果，在海水养殖尾水的氮硫污染控制中具有潜在的应用价值。

关键词:施氏假单胞菌;海水养殖尾水;硫化物;硝酸盐;生物修复

Abstract:

Objective To better control the pollution of nitrate and sulfide in mariculture tailwater and reduce the ecological risks caused by the discharge of the tailwater, this study screened a halotolerant desulfurizing and denitrifying bacterial strain and studied its growth characteristics.Methods A dilution coating-repeat dish sandwish culture method was used to isolate and screen halotolerant desulfurizing and denitrifying bacterial strains, which were identified by morphological observation and 16S rRNA gene sequence comparison. Based on single factor experiments, the key factors affecting desulfurizing and denitrifying effects, including carbon source, temperature, salinity, pH, and inoculation amount, were optimized, and the strain tolerance threshold to sulfide (S^2-) was explored.Results A strain Stutzerimonas stutzeri D1-2 was isolated from sulfur-based mixotrophic denitrifying sludge. This strain was able to simultaneously remove sulfide and nitrate from the environment with organic carbon sources. With sodium lactate as the optimal carbon source, strain D1-2 showed the best performance at an inoculation amount of 1.5%. The strain showed the removal rates of S₂O₃^2- and NO₃^--N both greater than 80% at 15-35 ℃, salinities of 10‰-50‰, and initial pH 6.0-8.0. It demonstrated significant tolerance at an initial S^2- concentration of 50 mg/L, with the removal rates of S^2- and NO₃^--N reaching 97.91% and 94.67%, respectively.Conclusion This study reports the heterotrophic sulfur-oxidizing capacity of S. stutzeri. The halotolerant strain S. stutzeri D1-2 capable of simultaneously desulfurizing and denitrifying has a potential application value in the control of sulfide and nitrate pollution in mariculture tailwater.

Key words:Stutzerimonas stutzeri;mariculture tailwater;sulfide;nitrate;bioremediation