In-situ nitrogen removal from the eutrophic water by microbial-plant integrated system

Objective： This study was to assess the influence of interaction of combination of immobilized nitrogen cycling bacteria （INCB） with aquatic macrophytes on nitrogen removal from the eutrophic waterbody, and to get insight into different mechanisms involved in nitrogen removal. Methods： The aquatic macrophytes used include Eichhornia crassipes （summer-autumn floating macrophyte）, Elodea nuttallii （winter-growing submerged macrophyte）, and nitrogen cycling bacteria including ammonifying, nitrosating, nitrifying and denitrifying bacteria isolated from Taihu Lake. The immobilization carriers materials were made from hydrophilic monomers 2-hydroxyethyl acrylate （HEA） and hydrophobic 2-hydroxyethyl methylacrylate （HEMA）. Two experiments were conducted to evaluate the roles of macrophytes combined with INCB on nitrogen removal from eutrophic water during different seasons. Results： Eichhornia crassipes and Elodea nuttallii had different potentials in purification of eutrophic water. Floating macrophyte＋bacteria （INCB） performed best in improving water quality （during the first experiment） and decreased total nitrogen （TN） by 70.2%, nitrite and ammonium by 92.2% and 50.9%, respectively, during the experimental period, when water transparency increased from 0.5 m to 1.8 m. When INCB was inoculated into the floating macrophyte system, the populations of nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 2 orders of magnitude compared to the un-inoculated treatments, but ammonifying bacteria showed no obvious difference between different treatments. Lower values of chlorophyll a, CODMn, and pH were found in the microbial-plant integrated system, as compared to the control. Highest reduction in N was noted during the treatment with submerged macrophyte＋INCB, being 26.1% for TN, 85.2% for nitrite, and 85.2% for ammonium at the end of 2nd experiment. And in the treatment, the populations of ammonifying, nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 3 orders of magnitude, as compared to the un-inoculated treatments. Similar to the first experiment, higher water transparency and lower values of chlorophyll a, CODMn and pH were observed in the plant＋ INCB integrated system, as compared to other treatments. These results indicated that plant-microbe interaction showed beneficial effects on N removal from the eutrophic waterbody.     

纤维素降解菌ZN-206的分离鉴定

采用连续稀释分离法和平板划线分离法的方法,利用以羧甲基纤维素钠为碳源的筛选培养基,从堆肥土壤中共分离获得具有纤维素酶降解能力的菌株15株,其中,菌株ZN-206对纤维素降解能力最强.根据ZN-206菌株的形态特征、培养性状,生理生化指标、细胞壁组成成分及16SrDNA序列进行系统的研究,将菌株鉴定为禾粟链霉菌(Streptomyces graminearus).     

耐高温乳酸菌的筛选

通过初筛、复筛,获得一株耐高温且产酸能力较强的菌株Y5,对该菌株进行了形态学和生理生化特性鉴定,确定此菌株为乳酸茵．通过单因素试验和正交试验确定菌株Y5的最佳产酸条件：发酵温度为55℃,转速为60r／min,接种量为7％,装液量为100mL．     

Wetland bacteria isolated from Huangpu River-Yangtze River estuary and its degradation on diesel

Oil contaminated soil was collected from Huangpu River-Yangtze River estuary wetland, with the aim of isolating oil-degrading microorganisms and evaluating their ability to degrade diesel. Three bacterial strains were discovered and identified by sequencing their 16S rDNA genes, two were Pseudomonas and one was Alcaligcnes. The proper growth conditions of each bacterium were measured and presented for diesel biodegradation. Biodegradation assays revealed that the degradation rates of three bacterial strains were 42.5%, 14.6% and 15.9% in 7 d respectively. They all play an important role on the nalkanes within the range of C16-C25 components of diesel. The results indicated that the oil-degraders can adapt to degrade diesel. The bacterial strains can be used in wetland diesel pollution control.     

生物技术修复湖泊水体性能研究

应用高效微生物光合细菌、硝化细菌、复合细菌降解水中污染物,对其修复性能进行研究.结果表明：投加微生物4 d后出现修复效果,20 d修复效果达到最佳状态,高锰酸盐指数（CODMn）、总氮（TN）、总磷（TP）、叶绿素a（Ch1.-a）都大幅下降;微生物最佳投加量150 mg/L,投加周期40 d.     

交流电对细菌Y—BAC的电刺激效应

以葡萄糖为唯一碳源,研究了细菌Y—BAC在交流电的刺激下细胞的生长和葡萄糖降解的过程．研究表：明对细菌施加交流电20min后,采用50-300Hz的交流电对细菌的脱氢酶没有明显的刺激效应;当对细菌施加交流电12h后时,细菌的脱氢酶和葡萄糖的降解和细菌细胞的通透性没有明显的变化．     

光合细菌沼泽红假单胞菌同化磷能力的研究

研究了光合细菌沼泽红假单胞菌WZ1同化磷的能力以及光照、碳源、pH值对其影响。实验结果表明：光照微好氧条件下该菌对磷的同化能力比黑暗微好氧条件下强；NaAc和苹果酸为碳源时，其同化磷的能力较乙醇为碳源时强；pH值为6．0，6．9和8．0下该菌同化磷的能力相似。在光照微好氧、NaAc或苹果酸为碳源、pH为6．9的条件下，该菌可同化0．020mg/mL左右的磷。     

On the origin of microbial magnetoreception

A broad range of organisms, from prokaryotes to higher animals, have the ability to sense and utilize Earth''s geomagnetic field—a behavior known as magnetoreception. Although our knowledge of the physiological mechanisms of magnetoreception has increased substantially over recent decades, the origin of this behavior remains a fundamental question in evolutionary biology. Despite this, there is growing evidence that magnetic iron mineral biosynthesis by prokaryotes may represent the earliest form of biogenic magnetic sensors on Earth. Here, we integrate new data from microbiology, geology and nanotechnology, and propose that initial biomineralization of intracellular iron nanoparticles in early life evolved as a mechanism for mitigating the toxicity of reactive oxygen species (ROS), as ultraviolet radiation and free-iron-generated ROS would have been a major environmental challenge for life on early Earth. This iron-based system could have later been co-opted as a magnetic sensor for magnetoreception in microorganisms, suggesting an origin of microbial magnetoreception as the result of the evolutionary process of exaptation.     

常熟市古城区河流水质卫生细菌学调查

采用平板菌落计数法和发酵法对常熟市古城区河流五个河段的水体进行了卫生细菌学调查．结果表明：常熟市古城区河流的水质受生活垃圾污染的情况比较严重,细菌总数均在 ４万／ｍＬ以上．大多数超过１０万／ｍＬ,最高达５６万／ｍＬ,大肠菌群数＞２３８００个／Ｌ．对城区水域的环境整治已刻不容缓．     

硫酸盐还原菌及其代谢途径

硫酸盐还原菌(sulfate-reducing bacteria,简称SRB)是一类能够以硫酸盐等氧化态硫化物作为电子受体的厌氧微生物.已分离研究的SRB有18个属近40多个种.由于硫酸盐还原在环境污染与防治中的独特作用,对硫酸盐还原菌及其代谢途径的研究渐趋广泛而深入.发掘新的硫酸盐还原菌,揭示硫酸盐还原过程,将推动生物脱硫技术的研发.