两株海水氮降解菌的分离鉴定及其无机氮去除特性初步研究

Isolation, Identification and Characterization of Two Marine Bacteria

为解决海水养殖环境中的无机氮污染问题,从河鲀(Takifugu rubripes)养殖池塘的水体和底泥中筛选出2株可有效去除氨态氮、亚硝态氮和硝态氮的菌株——盐单胞菌(Halomonas sp.DN3)和枯草芽孢杆菌(Bacillus subtilis HC),并初步探讨了2株菌在不同无机氮源中的氮去除特性。研究表明,2株细菌均具有较好的无机氮去除效果。在初始无机氮浓度为42 mg·L-1的单一氮源基础降解液中,菌株DN3对氨态氮、亚硝态氮和硝态氮的去除率分别为84.1%、62.1%和98.8%;菌株HC对三者的去除率分别为81.2%、49.0%和90.3%。在氨态氮去除过程中,虽未检测到硝态氮和亚硝态氮的积累,但从系统的氮收支分析,总氮浓度均显著下降,推测可能存在硝化过程;在硝态氮和亚硝态氮去除过程中,菌株DN3还原硝态氮时具有亚硝态氮的积累,菌株HC氧化亚硝态氮时具有硝态氮的积累。而从总氮浓度均有下降推测,可能存在好氧反硝化过程。在初始无机氮浓度为42 mg·L-1的混合氮源基础降解液中,2株菌均具有良好的同步去除无机氮能力。以氨态氮和亚硝态氮为氮源时,菌株DN3和HC的总无机氮去除率分别为75.4%和66.6%;以氨态氮和硝态氮为氮源时,菌株DN3和HC的总无机氮去除率为69.5%和75.6%,2株菌在2种混合氮源中的氨态氮去除率均在90.0%以上。综合分析,菌株DN3和HC对无机氮去除机制主要以菌体的同化作用为主,同时推测具有一定的硝化和反硝化作用。研究结果表明,菌株DN3和HC均可高效去除无机氮,其在海水养殖水环境调控中具有潜在的应用价值。

Halomonas sp.DN3 and Bacillus subtilis HC were isolated from Takifugu rubripes culture ponds.The inorganic nitrogen removal performance of the two bacteria was characterized further using ammonium chloride,sodium nitrite and sodium nitrate as the nitrogen sources.Two bacteria perform excellently in removing inorganic nitrogen in sole nitrogen source media containing 42 mg·L-1 nitrogen initially.The removal rate of NH+4-N,NO-2-N and NO-3-N by the strain DN3 reached 84.1%,62.1%and 98.8%,respectively,without nitrate and nitrite accumulations when ammonium was used.However,the nitrite was accumulated when sodium nitrate served as the sole nitrogen source.The strain HC performed differentially in removing nitrogen.Its maximum removal rate of NH+4-N,NO-2-N and NO-3-N was 81.2%,49.0%and 90.3%,respectively.No nitrate and nitrite was accumulated when ammonium chloride served as the sole nitrogen source.The nitrate started to accumulated when sodium nitrite served as the sole nitrogen source.The decrease of total nitrogen concentration indicated that nitrification and aerobic denitrification existed during nitrogen removal by two strains.Strains DN3 and HC showed also a high inorganic nitrogen removal rate in the media containing 2 mg·L-1 of mixed nitrogen initially.The total inorganic nitrogen removal rate of strains DN3 and HC reached 75.4%and 66.6%when ammonia and nitrite served as the nitrogen sources,respectively.When ammonia and nitrate served as the nitrogen sources,the total inorganic nitrogen removal rate of strains DN3 and HC was 69.5%and 75.6%,respectively.The NH+4-N removal rate of the two strains in the presence of two mixed nitrogen sources was more than 90.0%.In conclusion,strains DN3 and HC mainly remove inorganic nitrogen by assimilation,and nitrification and aerobic denitrification might also exist in the nitrogen removal process.These results revealed that strains DN3 and HC have a high inorganic nitrogen removing ability.They hold the potential of serving as the water environmental regulators.