摘要
从对虾池塘筛选得到1株高效的好氧反硝化细菌,命名为YX-6。对该菌生长及反硝化性能间的关系进行研究;同时研究了不同温度、pH、盐度及碳源对该菌生长及反硝化性能的影响。结果表明,该菌反硝化作用主要发生在对数生长期,可将亚硝酸盐氮由10mg/L降至0;该菌最适生长及反硝化温度为30℃;pH值范围为7～9时最适于该菌生长及反硝化性能的发挥。该菌最适盐度范围为0～15;丁二酸钠、乙酸钠为该菌生长及反硝化的最适碳源。通过对YX-6菌株生理生化及16SrRNA分子鉴定,初步鉴定为凝结芽孢杆菌(Bacillus coagulans)。对该菌株亚硝酸还原酶基因进行序列分析,结果表明,该菌含有亚硝酸还原酶nirS基因。
Nitrite is a matter of great concern for aquaculture since the excessive amount of nitrite poisons the aquatic animals,induces diseases outbreak and results in huge economic losses.This problem becomes more and more serious in intensive cultivation mode.Obviously,the conventional theory to remove nitrogen is based on the principle that denitrification is restricted to anoxic condition.It is not appropriate for aquaculture,because there is adequate oxygen in the culture water which is essential to aquatic animals.Although some probiotics are used in the aquaculture to improve the water quality in practice,their work mechanisms are described to reduce nitrite concentration indirectly by decomposing the organic matter.Probably the aerobic denitrifying microorganisms offer the suitable way to resolve this contradiction.In the present experiment,the aerobic denitrification of strain YX-6 screened from shrimp ponds was investigated under different temperature,pH,salinity and carbon sources.The results indicated that strainYX-6 removed the nitrite nitrogen from 10 mg/L to 0 mg/L within its logarithmic phase; The optimum temperature range was 25-35℃and it even maintained higher denitrification efficiency（above 90%）at 40℃;Its denitrification efficiency was approximately 100%at pH 7-9,while the optimum salinity ranged from 0 to 15.The results also proved that sodium acetate and sodium succinate were the best carbon sources for the strain YX- 6.In this study,partial sequences of 16S rRNA of strain YX-6 were amplified and searched against GenBank using the Advanced BLAST similarity search option accessible from the homepage at the National Center for Biotechnology Information（http：//www.ncbi.nlm.nih.gov/）.The MEGA 4.0 version（Arizona State University 2007）software was used to check alignment and construct the phylogenetic tree.According to the physiological and biochemical properties,and 16S rRNA sequencing and alignment,the YX-6 was identified as Bacillus coagulans primarily. Furthermore,the nitrite reductase genes of B.coagulans YX-6 was amplified and confirmed that it＇s nitrite reductase genes was nirS.As we know that temperature played an important role on the denitrificatin,the nitrite removal rate of B.coagulans YX-6 was over 90%even at 40℃,so it was supposed that its nitrite reductase could endure high temperature and the strain YX-6 could be suitable to be used in high temperature.Salinity was another factor to influence denitrifiction.In the study,when the salinity was over 15,the dennitrifiction efficiency decreased abruptly. which might be associated with the nitrite reductase.Different carbon resource may influence the dinitrification of aerobic denitrifying bacteria.Eight kind of carbon sources,sodium acetate,sodium succinate,lactic acid,seignette salt,sodium citrate,sodium salicytate,saccharose,glucose were tested and the results showed B.coagulans YX-6 could use small molecular carbon resources with higher efficiency and on the contrary for the macromolecular carbon resources.Although the nitrite reductase gene was amplified in this study,the relationship between denitrification and the properties of nitrite reductase of B.coagulans YX-6 was not clear and further research was needed.In conclusion, B.coagulans YX-6 could remove nitrite with high efficiency under high temperature and salinity condition and could be used in the aquaculture industry.
出处
《中国水产科学》
CAS
CSCD
北大核心
2010年第3期561-569,共9页
Journal of Fishery Sciences of China
基金
国家公益性行业专项(nyhyzx07-042)
国家公益性行业专项(NYCYTX-49-17)
农业部行业专项(200803013)
作者简介
作者简介：安健（1983-），男，硕士研究生，主要从事水产微生态制剂研发．E—mail：anjian520@sohu．com
通讯作者：杨先乐（1948-），教授，博士生导师，主要从事水产动物免疫、鱼类药理学与渔药的检测与监控等研究．E-mail：xlyang@shou.edu.cn.
