Use of microbial electrodes for observation of microbiological nitrogen elimination process

Microbial electrodes for the determination of ammonia and the estimation of biochemical oxygen demand (BOD) were applied to the nitrogen elimination process. The dimensions of the nitrification and the denitrification vessels were 170 and 70 L, respectively. The wastewater used for the experiment was obtained from a fermentation factory and adjusted to 470-530 mg/L of total Kjeldahl nitrogen and 1700-3000 mg/L of BOD. The ammonia electrode was assembled with a membrane containing nitrifying bacteria and an oxygen probe. The BOD electrode was similarly constructed, except it used a membrane containing the yeast, Trichosporon cutaneum. A flow system was employed for the automatic measurement of samples every 30 min. The nitrification and denitrification rates of the activated sludge were measured to investigate the optimum conditions and evaluate the capacity of the plant. The various data obtained by the microbial electrodes allowed us to inspect the situation of the plant and estimate control paramerers such as nitrogen and BOD loadings. The average removals of ammonia nitrogen and total Kjeldahl nitrogen were 96% and 89%, respectively, during the experiment for period of 2 weeks.     

信号分子在生物脱氮中的作用及检测方法

生物脱氮是由微生物主导的地球氮循环中的重要环节之一,主要包括硝化、反硝化和厌氧氨氧化(anaerobic ammonium oxidation,anammox)等过程。在微生物联合作用下,污水中的有机氮及氨氮经一系列作用转化为氮气,这种经济高效、环境友好的处理工艺在世界范围内得到广泛应用。群体感应(quorum sensing,QS)以信号分子为媒介通过改变菌群密度和周围环境变化来调节微生物的各种行为。大量的研究已证实调控QS信号分子在生物脱氮中具有应用潜力。本文介绍了各种信号分子类型,从基因组学、实际应用等方面综述了各类信号分子以及检测方法,同时针对酰基高丝氨酸内酯(acyl homoserine lactones,AHLs)类信号分子在生物脱氮中的作用进行详细介绍。然而不足之处在于信号分子研究只是停留在实验室阶段,仅仅研究了单一信号分子对生物脱氮的影响。未来可将信号分子应用于实际污水,研究多种信号分子共同作用以及多种微生物之间的QS现象。     

Evaluation of predominant factor for shortcut biological nitrogen removal in sequencing batch reactor at ambient temperature

Bioprocess and Biosystems Engineering - The shortcut biological nitrogen removal (SBNR) process requires less aeration and external carbon due to the oxidization of ammonia into nitrite and its...     

硝化细菌群的富集及其去除城镇寡营养河道中氨氮污染的应用

[背景]随着工农业的发展,污水排放导致的氨氮超标逐渐成为水体污染的重要因素,脱氮已成为人们研究的重点.目前脱氮方法主要集中于硝化细菌的硝化作用,其将氨氮转化为硝酸盐氮,从而减少水体中氨氮的污染.由于工业废水和农业污水中的有机物含量较高,而且异养硝化细菌具有生长较快等优势,因此对异养菌的研究多于自养菌.然而现有的异养硝化...     

Determination of cystathionine in rat tissues using isotachophoresis

A method for measurement of cystathionine in biological samples has been developed by using an isotachophoretic analyzer. The determination of the amount of cystathionine was carried out by measuring a zone length of cystathionine in isotachophoresis. The amount of cystathionine in brains of normal rats determined by using this method was 0.084 +/- 0.023 mumol/g. This value agreed well with earlier reports. The amount of cystathionine in rats with experimental cystathioninuria was determined in several tissues. The results determined by using this method for the determination of cystathionine in the rat tissues agreed well with the results obtained by using an amino acid analyzer.     

丹江口水库淅川库区大气氮湿沉降特征

大气氮沉降是除河流输入外水库水体重要的外源氮输入途径。以丹江口水库淅川库区为研究区,于2018年11月至2019年10月在库区周边设置了6个采样点,采集并分析了库区大气氮湿沉降样品,探讨氮湿沉降的时空分布特征以及对水库水体外源氮输入的贡献。研究结果表明,研究区大气氮湿沉降量为24.21 kg hm^-2 a^-1,其中氨氮占比（47.45％）为最大,有机氮占比（36.34％）次之,硝氮占比（16.21％）最小。硝氮湿沉降量在空间上表现出显著差异性。氨氮、有机氮湿沉降量的季节差异显著,氨氮是以夏季最高,秋季次之,冬季最低,而有机氮是以秋季最高,夏季次之,冬季最低。氨氮、硝氮、有机氮湿沉降量之间存在显著相关性,氨氮、有机氮湿沉降量与降水量之间存在显著相关性。总氮、氨氮湿沉降量分别为1321.98 t/a和627.34 t/a,分别占河流总氮、氨氮入库量的10.82％、34.85％。研究结果可为探索有针对性的库区水体氮污染控制途径提供重要理论基础。     

三种不同小球藻去除亚硝态氮和氨氮能力的研究

为了研究小球藻在不同质量浓度的氨氮和亚硝态氮环境下的去除能力与生长效果,从实验室挑选3株不同的小球藻CV315-1(Chlorella sp.)、CV315-2(Chlorella sorokiniana)和CV315-3(Chlorella pyrenoidosa)分别置于不同质量浓度的氨氮和亚硝态氮模拟污水中,在温...     

Improved method for EPR detection of DEPMPO-superoxide radicals by liquid nitrogen freezing

5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide (DEPMPO) is frequently used as a spin trap for the measurement of superoxide by EPR spectrometry. However, its half life is fairly short in room temperature. We here show that superoxide radicals trapped by DEPMPO can be successfully recorded at -196 degrees C. Moreover, we show that the signal intensity remains unaltered for up to 7 days, when the samples are stored in liquid nitrogen. Our new approach for measurement of superoxide should greatly simplify the studies of this important radical in biological systems.     

Separation of amino acid and amide nitrogen from plant extracts for 15N analysis

A rapid method was developed to obtain nitrogen for 15N analysis of individual amino acids and amides from plant tissue extracts. Amino or amide nitrogen was recovered as ammonia, suitable for preparation of samples for 15N emission spectrometry, using a combination of ion-exchange chromatography and distillation.     

Direct measurement of nitric oxide in headspace gas produced by a chicken macrophage cell line in a closed culture system.

A simple and rapid method was applied for direct measurement of nitric oxide (NO) gas produced by cultured macrophages using a modified chemiluminescence detector, the thermal energy analyzer (TEA). HD11 chicken macrophages (1-3 x 10(6)/ml) were cultured on microcarrier beads (100 mg/ml) in 140 ml air-tight glass jars (5 ml cell suspension per jar) containing 0.5 micrograms/ml of LPS and different concentrations of L-arginine. Headspace gas was sampled at 24 hours of culture via a rubber septum and directly injected into a TEA with a liquid nitrogen trap set at -130 to -140 degrees C. The concentration of NO in the gas sample was quantified using a standard gas mixture of NO (2 microliters/L) in nitrogen. Gas samples from L-arginine-supplemented cultures contained NO (0.028-0.066 pl/microliter), whereas NO was not detected in samples from controls. These results suggest that chicken macrophages synthesize NO gas in a dose-dependent manner relative to L-arginine concentration.     

Effect of high concentrations of nitrogen on mixed populations of nitrifying bacteria isolated from industrial nitrogenous wastewaters.

The effect of high concentrations of different forms of nitrogen (NH4+, NO2-, NO3- and urea N) on nitrification by mixed populations of nitrosobacters isolated from nitrogen fertilizer plant wastewaters and nitrobacters isolated from effluents from a biological bed treating these wastewaters was determined. The inhibitory activity (within the concentration values for industrial wastewaters) of only the reaction products was observed, i.e. nitrites for nitrification phase I and nitrates for nitrification phase II. A mixed population of phase II nitrifying bacteria is highly resistant to high concentrations of ammonia nitrogen (50% inhibition at 3,000 mg N/l).     

Enzymology and ecology of the nitrogen cycle

The nitrogen cycle describes the processes through which nitrogen is converted between its various chemical forms. These transformations involve both biological and abiotic redox processes. The principal processes involved in the nitrogen cycle are nitrogen fixation, nitrification, nitrate assimilation, respiratory reduction of nitrate to ammonia, anaerobic ammonia oxidation (anammox) and denitrification. All of these are carried out by micro-organisms, including bacteria, archaea and some specialized fungi. In the present article, we provide a brief introduction to both the biochemical and ecological aspects of these processes and consider how human activity over the last 100?years has changed the historic balance of the global nitrogen cycle.     

固定化微生物处理氨氮废水的研究进展

生物方法因其高效、持久及无二次污染已经成为治理水污染的重要方法,固定化微生物不仅加强微生物治理效果,更能保证微生物生存稳定,是现阶段生物方法治理水污染的主要组分。近年来学者们也做了很多固定化微生物处理各类废水的研究,并取得了大量优异成果。文章对固定化微生物技术进行剖析,分析各类固定化载体材料及各种固定化方法优缺点;解析利用固定化微生物处理氨氮废水效果研究及固定化微生物处理效果影响因素;综述近年来固定化微生物处理氨氮废水应用情况;最后进行总结,并提出自己的展望。     

粤东柘林湾无机氮的时空分布特征

2000年5月～2001年5月对粤东柘林湾海域调查结果表明该湾三氮分布呈湾内向湾外递减趋势,湾内以西部海域含量为高。NO₃-N是柘林湾无机氮的主要存在形态,其含量呈冬春季高、夏秋季低的特点。NH₄-N和NO₂-N与盐度的相关性较差,NO₃-N则除秋季外,其余季节与盐度均呈良好的负相关关系,表现保守性行为。     

高氨氮利用酵母菌的筛选及相关酶活性

【背景】蛋白饲料的缺乏,促进了蛋白含量高、安全性能好的酵母类单细胞蛋白的研究与应用。【目的】筛选氨氮利用能力强的菌株,为单细胞蛋白的发酵提供优良菌株。【方法】从土壤、奶制品、水果采集样品分离酵母菌,根据形态学和分子生物学鉴定菌株,然后以硫酸铵为唯一氮源培养基,测定菌落大小、菌体干重、蛋白质含量,复筛氨氮利用率高的酵母菌,并对复筛菌株氨同化相关酶活性进行测定。【结果】经过形态学、分子生物学鉴定和氨氮利用能力评价,获得3株高氨氮利用的酵母菌,分别是胶红酵母(Rhodotorula mucilaginosa)、酿酒酵母(Saccharomyces cerevisiae)和戴尔有孢圆酵母(Torulaspora delbrueckii)。通过比较3株酵母菌的谷氨酸脱氢酶、谷氨酸合成酶、谷氨酰胺合成酶活性,酿酒酵母的3种酶活性最高,其次是胶红酵母。【结论】从奶酪和西瓜中分离的胶红酵母N5和酿酒酵母J1具有较强的氨氮利用能力以及酶活性,可为单细胞蛋白发酵提供优良菌株。     

Use of an alternative method for monitoring total nitrogen concentrations in Florida lakes

We studied a recently described method for the determination of total nitrogen in natural waters involving sample oxidation with persulfate and subsequent determination of nitrate-nitrogen with second derivative spectroscopy and compared it to the USEPA approved method involving the sum of nitrate-nitrogen and Kjeldahl-nitrogen as measured with an automated analyzer. The overall objective was to determine if the two methods gave the same estimates of total nitrogen and if the detection limits, precision and accuracy of the new method were as good as those of the USEPA method. The new method was used to make measurements on replicated blanks, standards and lake water samples covering a range of concentrations. We also collaborated with certified laboratories to make comparative measurements on 5 standards and 21 lake water samples that were run by us with the new method and by them with the USEPA method. The new method had an instrument detection limit of 0.07 mg 1^–1, and the standard deviation of 20 sets of lake water samples averaged 0.03 mg 1^–1. The new method gave concentrations equivalent to those found with the USEPA method, was more sensitive, and had a higher degree of precision. We concluded that the new method is suitable as a substitute for the USEPA method. We also found that the addition of acid to lake water samples stored under refrigeration was not necessary to preserve them for later determinations of nitrate-nitrogen and total nitrogen and that freezing was an effective means of sample preservation for 90 days.     

Effect of dissolved oxygen on nitrogen fixation by A. vinelandii. I. Free cell cultures

As part of an investigation into the use of biological nitrogen fixation for fertilizer ammonia production, continuous culture studies of respiration and nitrogen fixation in the aerobic bacteria Azotobacter vinelandii under oxygen-limited conditions were conducted. Respiration and growth rates followed Monod forms with respect to dissolved oxygen concentration. However, specific nitrogen fixation rate and nitrogenase activity exhibited maximum values at dissolved oxygen concentrations of ca. 0.02 mM (10% of air saturation). These results suggest careful control of oxygen in the environment is necessary to optimize fixed nitrogen production by this organism.     

粉粒氨氮和水分影响浮霉菌门群落的空间分化

【背景】来自浮霉菌门(Planctomycetes)的厌氧氨氧化菌是高氨污染系统安全脱氮的生态友好型微生物,但关于特定生态梯度下Planctomycetes群落结构功能的空间分化以及驱动分化的主要环境因子等问题尚未引起关注。【目的】阐明Planctomycetes群落结构空间分化及影响其分化的主要环境因子。【方法】运用16S rRNA基因高通量测序手段检测温带半干旱区河流系统砂质及粉质沉积物、粉砂质及粉质土壤Planctomycetes群落结构的空间分布变化,统计学方法分析粉粒等理化因子对Planctomycetes群落结构功能分化的影响。【结果】OM190_ub_oo. o1种群主要分布在寡营养的砂质沉积物中,仅由砂粒正向驱动;OM190_ooo. o2和SM1A02. ub5种群主要分布在中营养的粉砂质土壤中,由水分和pH等正向驱动;AKYG587.ub3、Pla4_lineage_oo...     

Diel patterns of nitrogen excretion, plasma constituents, and behavior in the gulf toadfish (Opsanus beta) in laboratory versus outdoor mesocosm settings

Nitrogen excretion by the gulf toadfish (Opsanus beta) is of interest because of its high proportion of urea excretion compared with that of other teleosts. To better understand the factors influencing the timing of nitrogen excretion, the ratio of excreted urea∶ammonia, and the effector molecules regulating these processes, gulf toadfish were subjected to a series of experiments that moved them progressively from internal laboratory to outdoor mesocosm settings while assessing their behavior, nitrogen excretion patterns, levels of plasma hormones/effectors, and other parameters. In confined flux chambers in both laboratory and outdoor settings, toadfish nitrogen excretion was largely observed as urea pulses, with no apparent diel patterns to the pulses. Unrestrained toadfish in mesocosms exhibited distinctly nocturnal behavior, remaining exclusively in shelters during the day but taking several forays out into the mesocosm at night. In contrast to nitrogen excretion patterns in chambers, urea and ammonia were coexcreted in mesocosms and ratios for urea∶ammonia were very close to 1∶1 for both fed and fasted toadfish. The majority of measured excretion (and corresponding declines in plasma urea levels) occurred during two distinct periods of pulsing during daylight hours (0600-1000 and 1600-1800 hours). The declines in plasma urea associated with excretion were preceded by/coincided with declines in plasma cortisol. No day/night or hourly patterns in plasma serotonin (5-hydroxytryptamine [5-HT]) were observed, but there was a strong positive correlation among all samples between plasma urea and 5-HT. There was also a negative correlation between plasma cortisol and 5-HT. As expected for a nocturnally active species, plasma melatonin was significantly lower in daylight hours. A variety of enzyme activities (glutamine synthetase, glutaminase) and mRNA levels (glutamine synthetase, urea transporter, and Rhesus proteins) showed no significant variation over a diel cycle. Unlike prior laboratory studies, our results show that gulf toadfish in a natural setting have a distinctly diurnal pattern of nitrogen excretion and that ammonia and urea are coexcreted. The decline in plasma cortisol associated with urea pulses noted in prior laboratory studies was not as evident in the natural setting.