Degradation characteristics and metabolic pathway of 4-nitrophenol by a halotolerant bacterium Arthrobacter sp. CN2

Arthrobacter sp. strain CN2, capable of degrading 4-nitrophenol, was isolated from activated sludge. Degradation of 4-nitrophenol was optimized at pH 7.7, 30?°C, and 0.53% of glucose. Salt tolerance of 4-nitrophenol degradation was as high as 6% (w/v). Several biodegradation intermediates were identified and quantified by high-performance liquid chromatography and mass spectrometry. 4-Nitrocatechol is involved in the degradation of 4-nitrophenol by CN2. Scale-up of 4-nitrophenol degradation was conducted in a bioreactor with different salinity. When the salinity was below 7%, the degradation rate of 4-nitrophenol was above 90% (100 mg L^?1, 3 L).     

3DBER-S反硝化脱氮性能及其菌群特征

针对污水处理厂尾水TN去除问题,采用16S rDNA克隆文库法,探究了3DBER-S(三维电极生物膜耦合硫自养脱氮工艺)的强化脱氮机制及其菌群特征. 结果表明,I(电流)和HRT(水力停留时间)对3DEBR-S中氢自养和硫自养反硝化作用所占比例的影响较大,但对脱氮效率影响不显著. 当进水C/N〔ρ(COD_Cr)/ρ(TN)〕为1、ρ(NO₃--N)为35 mg/L、I为300 mA、HRT为4 h时,NO₃--N和TN去除率可分别稳定在80%和74%以上. 16S rDNA克隆文库结果显示,反应器中β变形菌纲为优势菌群,占47.89%〔以OUT(操作单元)计〕. 在β变形菌纲中,与具有反硝化功能的陶厄氏菌属(Thauera)相似的细菌所占比例最大,为52.94%;与可分别利用硫和氢为电子供体进行反硝化脱氮的硫杆菌属(Thiobacillus)和食酸菌属(Acidovorax)相似的细菌分别占17.65%和14.71%. 3DBER-S中存在异养联合氢自养和硫自养反硝化协同去除硝酸盐氮的作用,可为反硝化脱氮提供充足的电子供体,节约了有机碳源消耗,并保证了稳定高效的脱氮效果.      

碳磷比对SND过程污染物去除及N2O释放的影响

以两个平行运行的SBR反应器为研究对象,研究了碳磷比对同步硝化反硝化过程中污染物去除及温室气体N2O释放的影响.结果表明:系统对COD和氨氮的去除率均能达到90%以上,总磷和总氮去除率随碳磷比的降低而提高,这是由于低碳磷比下聚磷菌得到富集,同时部分聚磷菌利用NO3-和NO2-为电子受体吸收磷,从而实现脱氮除磷的同步提高.系统的N2O释放量随碳磷比的降低而降低,低碳磷比下N2O释放量仅为高碳磷比的76%.低碳磷比下N2O释放量的减少主要是由于异养反硝化过程对N2O释放的贡献降低导致的.     

不同EPS组成生物膜对Cu2+吸附的研究

采用自行设计的反应器,通过调节培养液的配比对载体进行挂膜,得到蛋白质和多糖含量比分别为7:1、5:1和10:1的3种生物膜作为吸附剂,用其对Cu2+进行吸附试验,同时对吸附机理进行探讨.结果表明,培养8d后,生物膜可挂膜成熟,在C/N=12时,生物膜上的菌落数较C/N=4和C/N=37条件下多.PN/PS值越小,生物膜对铜的吸附量越高,EPS3对Cu2+的吸附量分别高出EPS1 7.37 %, EPS2 7.62%.在生物膜吸附Cu2+后,溶液中Ca2+、Mg2+、K+含量明显升高,表明离子交换对生物膜吸附Cu2+起主要作用,且Cu2+更易与Ca2+和Mg2+产生离子交换作用.当KNO3浓度在0.1~0.6mol/L之间,随着离子强度的增加,生物膜吸附Cu2+的量迅速减少,当KNO3浓度大于0.6mol/L时,生物膜对Cu2+吸附量的变化趋于平缓,说明生物膜对Cu2+的吸附同时包括离子交换吸附和化学吸附.     

致癌性卤代醌介导的脂质氢过氧化物分解的分子机制

卤代醌是许多卤芳香持久有机污染物的致癌代谢产物和饮用水消毒副产物.13-过氧羟基-9,11-十八碳二烯酸(13-HPODE)是最为广泛研究的内源性脂质过氧化物.众所周知,过渡金属离子可以催化分解13-HPODE,但尚不清楚卤代醌是否可以通过不依赖金属离子的途径促进其分解;若是如此,又有什么特异性和相似性?我们发现卤化醌如2,5-二氯-1,4-苯醌(DCBQ)可显著促进13-HPODE的分解.综合采用电子自旋共振-自旋捕获、HPLC-MS和GC-MS等分析方法,可检测到反应形成的脂质烷基自由基如戊烷基自由基、7-羧甲基自由基以及具有基因毒性的4-羟基-2-壬烯醛(HNE)等.在DCBQ和13-HPODE的反应中也能检测到两种氯醌-脂质烷氧基耦合物.我们认为卤代醌促进内源性脂质过氧化物13-HPODE分解生成活性脂质烷基自由基和基因毒性的HNE是通过一类新型的金属非依赖亲核取代与裂解机理来实现的,这也在一定程度上解释了其潜在的基因毒性和致癌性.     

Validation of the UN test method N.5

Many substances react with water in such a way that flammable gases are formed. For transport issues this reaction may possess a considerable hazard especially if the cargo is wetted by rain or by water from other sources. In the UN Recommendations on the Transport of Dangerous Goods these kinds of problems are addressed. The UN test N.5 “Test method for substances which in contact with water emit flammable gases” corresponds to this hazard. Classification according to the test method is done by measurement of the gas evolution rate of the flammable gas by any suitable procedure. At BAM a gravimetric approach is used to measure the gas evolution rate. In this paper we present the evaluation of the apparatus by means of an absolute calibration routine utilizing a reaction where a known amount of gas is produced as well as the evaluation of important parameters influencing the gas evolution rate using different substances. It can be shown that the apparatus is capable of measuring absolute gas volumes as low as 6 mL with an acceptable error of about 17% as determined from the reaction of Mg with demineralized water.     

DMF降解菌MBYD-1的分离、鉴定及降解特性

从农药厂污水处理池的活性污泥中分离得到一株能以二甲基甲酰胺(DMF)为唯一碳、氮源生长的菌株MBYD-1.经形态观察、生理生化实验及16S rRNA基因序列分析,将菌株初步鉴定为假单胞菌属 (Pseudomonas sp.).菌株MBYD-1降解DMF的最适条件为:pH 7.0,30℃.当DMF浓度为400mg/L,接种量为2%时,菌株能在72h内将DMF完全矿化.底物广谱性实验表明,菌株MBYD-1能在甲酸盐和甲醛中很好地生长,在甲酰胺中的生长情况优于二甲胺.     

光合细菌对2,4,6-三氯苯酚的降解特性研究

研究了混合光合细菌PSB-DR在不同光照、接种量和pH值下对2,4,6-三氯苯酚(2,4,6-TCP)的生物降解特性,确定了PSB-DR生物降解2,4,6-TCP的优化控制条件.结果表明,光照培养下,接种量30%,初始pH值7.0时2,4,6-TCP降解效率最高.在此条件下,50mg/L的2,4,6-TCP经5d后降解率达到82.3%.培养基中醋酸钠的加入对2,4,6-TCP降解有明显的抑制作用.PSB-DR静息细胞对2,4,6-TCP的降解符合高浓度底物抑制的酶促反应类型,其降解动力学参数rmax=1.746h-1,Km=38.333mg/L,Ki=260.87mg/L.     

Determination of 4-nonylphenol in carp blood samples by solid phase extraction and chromatographic techniques

In this study, selective methods were developed for isolation, purification, separation and determination of 4-nonylphenol (4NP) in biological samples. Several methods such as high-performance liquid chromatography (HPLC) with fluorescence and diode array detection and gas chromatography coupled to mass spectromotry (GC-MS) are described for the simultaneous determination of 4NP. The nonylphenols in the plasma of fish were extracted through solid phase process by using octadecyl, polymeric and octadecyl endcapping sorbents. The average recoveries in plasma samples spiked with 4NP of levels 1?µg?mL^?1 were between 80–95% using added surrogate standards. The aim of this study was to determine whether trace amounts of 4NP in fish plasma samples could be detected by solid phase extraction and chromatographic methods (HPLC, GC-MS). This technique of monitoring the levels of endocrine-disruptors in plasma samples is consistent, reliable as well as inexpensive.