一株高效耐冷菌的分离鉴定及降解特性研究

寒冷地区水温偏低,污水生物处理效果差,出水达标困难。从寒冷地区水土样品中,分离到数株能在2℃下生长的低温菌株,选择优势菌N进行重点研究。从脱氢酶活性机制上,考察了不同条件对N菌株降解能力的影响;对比研究了它与常温活性污泥降解能力和脱氢酶活性的差异。结果表明:N菌株属于耐冷型低温微生物,结合16S rDNA序列同源性分析及生理生化特性鉴定为黄假单胞菌;5℃曝气8 h,接种废水COD、氨氮去除率均在90%以上;低温条件下,该耐冷菌对生活污水降解率比常温活性污泥高出40%,脱氢酶具有更高的活性,在低温污水处理方面具有广阔的应用前景。     

具有降解亚硝酸盐活性的解淀粉芽孢杆菌的分离与安全性分析

从养殖污泥中分离筛选了一株优良的亚硝酸盐降解菌YX01,经ARIS 2X细菌自动鉴定系统以及16SrRNA系统发育分析,该菌株被鉴定为解淀粉芽孢杆菌(Bacillus am yloliquefaciens,GenBank登录号为JX649949),其16S rRNA序列与基因库中 芽孢杆菌属菌株的16S rRNA序列有99％～100％的同源性,而且与解淀粉芽孢杆菌菌株LD5(GenBank登录号:GQ853414)的亲缘关系最近.该亚硝酸盐降解菌YX01在浓度为2.0×107～2.0×109cfu/L时对小球藻(Chlorella sp.)生长有促进作用;在浓度大于2.0×1011cfu/L时对小球藻生长具有显著抑制作用;亚硝酸盐降解菌YX01对小球藻的半数抑制浓度(IC50)大于2.0×1011cfu/L.亚硝酸盐降解菌YX01对大型蚤(Daphnia magna)的48h-半数致死浓度(LC50)大于2.0×1011cfu/L,对草鱼(Ctenopharyngodon idellus)的96h-LC50大于2.0×1011cfu/kg.经分析,亚硝酸盐降解菌YX01为无毒菌株.     

纳污水体中好氧脱氮菌的筛选与氨氮去除特性

采用异养硝化培养基从城市纳污水体中富集好氧脱氮菌,将得到的富集菌种分离纯化,得到1株好氧脱氮菌NC1,对氨氮的去除率为72.6%;好氧菌株NC1繁殖较快,生长3~4 h即进入对数生长期,有一定实用意义。考察了在不同条件下菌NC1对氨氮的去除效果,发现当pH为6~9之间、转速超过100 r/min、温度为30℃、碳氮比为6~12时对氨氮的去除效果较好。NC1在去除氨氮过程中pH值升高,且能在异养条件下利用亚硝酸盐和硝酸盐生长。     

畜禽养殖污水中高效氨氮降解菌的筛选、鉴定及生长条件研究

从养殖污水中分离纯化得到1株高效氨氮降解菌,对其进行形态特征、生理生化、16S rDNA序列分析以及最佳生长条件研究,并将菌株投入养殖污水降解污水中的氨氮。结果表明：AN4菌株在NH4＋-N初始质量浓度为50 mg/L的条件下,24 h内的氨氮降解率为92.5%;初步鉴定该菌株为苍白杆菌属（Ochrobactrum sp.）,菌株的16S rDNA序列在Gen-Bank的登录号为GU345782;AN4菌株在装液量为60.64 mL,pH为7.06,葡萄糖为6.0 g/L的条件下培养,菌株的降解率可以达到94.28%;菌株对养殖污水中氨氮的降解率为12.3%。苍白杆菌菌属能够降畜禽养殖污水中的氨氮还未见报道,AN4菌株的筛选获得为生物降解养殖污水中的氨氮又提供了一种新型菌株。     

高盐条件下硝基苯降解菌的分离及降解特性

在高盐条件下,从某制药厂曝气池的活性污泥中分离、筛选得到6株硝基苯高效降解菌,其中菌株N18在高盐条件下对硝基苯降解效率最高.经形态特征和生理生化特征分析,初步鉴定N18属于棒状杆菌属(Corynebacterium sp.).硝基苯降解试验表明,菌株最佳培养条件为30℃、培养基pH 7、摇床转速150 r/min.最佳培养条件下,当硝基苯初始质量浓度低于150 mg/L时,菌株培养72 h后硝基苯降解率达75％以上.当盐度为1％～3％时,盐度对硝基苯降解率的影响不明显,当盐度为10％时菌株生长微弱,因此N18属于中度耐盐细菌.     

污染水体中氨氮降解菌的筛选与降解特性研究

为研究污染水体中微生物对氨氮的降解能力,寻求安全有效的治理技术,从浙江安吉南北湖的底泥中分离筛选出12株具有氨氮降解能力的菌株X1至X12,以(NH_4)_2SO_4为唯一氮源,对比12株菌株的生长情况与氨氮降解率,挑选出脱氮能力较强的菌株X1和X2。活化后的菌株X1和X2反应48h,氨氮降解率分别为98.05%、97.63%,且反应体系的亚硝酸盐氮和硝酸盐氮积累均极少。未经活化的菌株X1和X2反应48h,氨氮降解率分别为96.40%、97.90%,也未出现明显的硝酸盐氮和亚硝酸盐氮积累。通过观察形态特征、测定生化性质和比对16SrDNA序列,鉴定出菌株X1为浅黄色假单胞菌(Pseudomonas lurida),菌株X2为Pseudomonas weihenstephanensis。菌株X1和X2生长速率快,易成为优势菌种,降解氨氮能力显著,在污染水体生物修复领域具有良好的应用前景。     

硝化菌的筛选、鉴定及其固定化颗粒的氨氮去除效能

为探讨氨氮微污染地表水的生物强化脱氮技术,从地表水中筛选分离得到一种硝化菌优势菌株,对其进行16SrDNA鉴定,考察了不同固定化方法条件下其对氨氮处理的效果。结果表明,从氨氮微污染地表水中筛选分离的硝化菌优势菌株为芽孢杆菌属(Bacillus sp.),采用聚乙烯醇(PVA)材料能够有效实现硝化菌株的固定化。PVA固定化硝化菌颗粒对微污染地表水中氨氮的去除率达87.2%,处理后水中残余氨氮浓度低于《地表水环境质量标准》(GB 3838—2002)Ⅱ类水体氨氮限值。     

A.faecalis strain NR的包埋固定及其氨氮降解性能

为考察异养硝化-好氧反硝化细菌的包埋固定及其氨氮降解特性,对一株异养硝化-好氧反硝化细菌A.feacalis strain NR的包埋固定进行了研究,并与游离菌处理氨氮效果进行对比,考察包埋菌降解氨氮的优势。采用聚乙烯醇(PVA)、海藻酸钠(SA)以及PVA/SA混合物分别作为包埋载体,发现PVA/SA混合物作为包埋载体其理化性能最佳,更适合作为包埋载体;利用单因素实验寻求PVA及SA含量、交联时间、包菌量4个因素的合理水平,并采用正交实验对上述4个因素进行优化,获得包埋较优条件为:PVA含量10%、SA含量0.4%、交联时间4 h、包菌量10%;在此条件下制备包埋小球,并得出包埋小球在基础培养基中的最佳投加量为10 g/(150 m L基础培养基);之后考察了温度、pH这2个因素对包埋小球降解氨氮效果的影响,得到包埋小球的最佳氨氮降解条件为:30℃、pH=7;通过对比不同温度及不同pH条件下包埋小球与游离菌对于氨氮的处理效果,发现包埋小球对低温及酸性条件更具有耐受性,表现出优于游离细菌的氨氮降解效率。     

沉积物中2株多环芳烃降解菌的分离鉴定及其对菲、荧蒽的降解特性

从长江重庆主城段近岸表层沉积物中,分离出2株能以菲和荧蒽为碳源和能源生长的菌株(命名为CJ1、CJ2),经鉴定分别为黄杆菌属(Flavobacterium sp.)和克雷伯氏杆菌属(Klebsiella sp.)。进行了菲和荧蒽在初始浓度为20~200 mg/L条件下的生长代谢过程与降解动力学分析。结果表明,CJ1对菲和荧蒽的降解效能总体优于CJ2。15 d时CJ1和CJ2对菲的降解率最高分别为74.3%和70.3%;30 d时CJ1和CJ2对荧蒽的降解率最高分别为58.2%和49.9%。初始浓度为200 mg/L时,两菌株对菲、荧蒽的降解受到一定程度抑制。     

混合耐冷菌群的优化筛选及应用研究

从冬季时污水处理厂曝气池的活性污泥中分离出高生物活性的耐冷细菌和耐冷酵母菌,以低温生活污水为处理对象,分别测定单株菌及混合耐冷菌群有机污染物降解能力.结果表明,共分离出从属于黄杆菌属、假单胞菌属、芽胞杆菌属等的耐冷细菌6株;从属于毕赤酵母菌属、假丝酵母菌属、红酵母菌属等的耐冷酵母菌4株.耐冷菌在5℃条件下具有相对较短的世代时间:9.04～13.11 h.单株耐冷细菌F和耐冷酵母菌AH在5℃条件下的COD去除率分别为64%和83%.混合耐冷菌群经驯化后可较高地去除低温生活污水中的有机污染物,COD去除率可保持在83%～87%.     

Evaluation of trichloroethene recovery processes in heterogeneous aquifer cells flushed with biodegradable surfactants

The ability of two biodegradable surfactants, polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium dihexyl sulfosuccinate (Aerosol MA), to recover a representative dense non-aqueous-phase liquid (DNAPL), trichloroethene (TCE), from heterogeneous porous media was evaluated through a combination of batch and aquifer cell experiments. An aqueous solution containing 3.3% Aerosol MA, 8% 2-propanol and 6 g/l CaCl(2) yielded a weight solubilization ratio (WSR) of 1.21 g TCE/g surfactant, with a corresponding liquid-liquid interfacial tension (IFT) of 0.19 dyn/cm. Flushing of aquifer cells containing a TCE-DNAPL source zone with approximately two pore volumes of the AMA formulation resulted in substantial (>30%) mobilization of TCE-DNAPL. However, a TCE mass recovery of 81% was achieved when the aqueous-phase flow rate was sufficient to displace the mobile TCE-DNAPL toward the effluent well. Aqueous solutions of Tween 80 exhibited a greater capacity to solubilize TCE (WSR=1.74 g TCE/g surfactant) and exerted markedly less reduction in IFT (10.4 dyn/cm). These data contradict an accepted empirical correlation used to estimate IFT values from solubilization capacity, and indicate a unique capacity of T80 to form concentrated TCE emulsions. Flushing of aquifer cells with less than 2.5 pore volumes of a 4% T80 solution achieved TCE mass recoveries ranging from 66 to 85%, with only slight TCE-DNAPL mobilization (<5%) occurring when the total trapping number exceeded 2 x 10(-5). These findings demonstrate the ability of Tween 80 and Aerosol MA solutions to efficiently recover TCE from a heterogeneous DNAPL source zone, and the utility of the total trapping number as a design parameter for a priori prediction of DNAPL mobilization and bank angle formation when flushing with low-IFT solutions. Given their potential to stimulate microbial reductive dechlorination at low concentrations, these surfactants are well-suited for remedial action plans that couple aggressive mass removal followed by enhanced bioremediation to treat chlorinated solvent source zones.     

The variation of street air levels of PAH and other mutagenic PAC in relation to regulations of traffic emissions and the impact of atmospheric processes

The occurrence of particle associated PAH and other mutagenic PAC was determined in 1996 in the street air of Copenhagen. In addition, particle extracts were tested for mutagenicity. The measurements were compared with previous measurements in 1992/1993. The levels had decreased in this period. The decrease was caused by an implementation of light diesel fuels for buses and the exchange of older petrol-driven passenger cars with catalystequipped new ones. About 65% of the reduction was caused by the application of the light diesel fuels. Under special conditions, chemical processes in the atmosphere produced many more mutagens than the direct emissions. The concentrations of S-PAC and N-PAC were 10 times lower than those of PAH, while the levels of oxy-PAH were in the same order of magnitude as those of PAH. Benzanthrone, an oxy-PAH, is proposed to be formed in the atmosphere in addition to direct emissions. Benzo(a)pyrene, often applied as an air quality criteria indicator, was photochemically degraded in the atmosphere. A strong increase in the mutagenic activities was observed to coincide with a depletion of benzo(a)pyrene.     

Chloroaromatic pollutants in mussels incubated in two finnish watercourses polluted by industry

Concentrations of different chlorinated compounds were measured in mussels incubated in two polluted watercourses, a river (the River Kymijoki) and a lake (Lake Vanaja) for four weeks in summer 1995. The sum concentrations of polychlorinated phenols (PCP) and biphenyls (PCB) were both about 1 μg/g lipid weight (lw) in Lake Vanaja mussels, while in the River Kymijoki mussels PCPs were non-detectable and PCBs were measured 120 ng/g lIw. The concentrations of toxic polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) congeners ranged between <17 and 370 pg/g Iw in Lake Vanaja mussels and between <38 and 11,000 pg/g lw in the River Kymijoki mussels. Polychlorinated diphenyl ethers (PCDE) were detected in the mussels incubated in the River Kymijoki (0.4–1.1 ng/g Iw), but not in those incubated in Lake Vanaja. Polychlorinated phenoxyanisoles (PCPA) were measured 33 ng/g lw and polychlorinated phenoxyphenols (PCPP) 300 ng/g lw in the mussels incubated in the River Kymijoki. PCPAs were also detected in reference samples, which were sediment and pike from the River Kymijoki and Baltic salmon, seal and white-tailed sea eagle.     

Teratological effects of pesticides in vertebrates: a review

Abstract

In the last decades, the use and misuse of pesticides in the agriculture have increased, having a severe impact on ecosystems and their fauna. Although the various effects of pesticides on biodiversity have been already documented in several studies, to our knowledge no consistent overview of the impact of pesticides in vertebrates, both terrestrial and aquatic, is available. In this review, we try to present a concise compilation of the teratogenic effects of pesticides on the different classes of vertebrates – mammals, birds, reptiles, amphibians and fish.     

Book review

The Pesticide Manual ‐ A World Compendium, 8th Edition, C.R. Worthing, Editor and S.B. Walker, Assistant Editor, British Crop Protection Council, BCPC Publications Sales, Bear Farm, Binfield, Bracknell, Berkshire RG12 5QE, England. 1987, 1100 pp., UK £50; Overseas £56. ISBN 0–948404–01–9.     

Patterns of volatile metabolites and nonvolatile trichothecenes produced by isolates of <Emphasis Type="Italic">Stachybotrys,Fusarium, Trichoderma,Trichothecium</Emphasis> and <Emphasis Type="Italic">Memnoniella</Emphasis>

We reported previously that trichodiene, a volatile trichothecene derivative, was produced by a Stachybotrys isolate, also known to produce highly cytotoxic, non-volatile, macrocyclic trichothecenes (satrotoxins). We investigated the relationship between the production of trichodiene and various non-volatile trichothecenes for several molds. Volatile metabolites were concentrated by adsorption on Tenax TA and analyzed by GC/MS, while non-volatile metabolites were separated by HPLC, derivatized and analyzed by GC/MS. Stachybotrys chartarum isolates producing macrocyclic trichothecenes secreted significantly larger amounts of trichodiene and other sesquiterpenes than isolates which only produced simple trichothecenes. The amounts of secreted trichodiene were relatively small in all cases. With the exception of Memnoniella, which excreted small amounts of sesquiterpenes, the other isolates produced varying amounts of sesquiterpenes, including trichodiene, as well as simple tricothecenes, no detectable trichodiene, but large amounts of griseofulvin derivatives. In Stachybotrys there is apparently a correlation between trichodiene and macrocyclic trichothecene production. In the remaining isolates, there was no simple relationship between trichodiene and non-volatile trichothecene synthesis. Trichodiene is produced in larger amounts by Stachybotrys isolates, which also produce satratoxins, but it will be difficult to utilize this metabolite to detect toxic isolates in buildings due to the relatively small amounts excreted.     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

Knowledge transfer initiative between molecular biologists and environmental researchers and regulators

A Natural Environment Research Council (NERC) funded Knowledge Transfer (KT) workshop was held in the United Kingdom (UK) to identify the needs and opportunities in the application of molecular biology and ‘omics’ techniques to environmental monitoring and risk assessment. Attendees highlighted a lack of effective communication between end-users and researchers as well as difficulties with data interpretation as reasons behind the slow uptake of molecular biology and omics techniques. A number of promising areas in which new techniques could be implemented at a practical level in the very near future were identified, thereby raising the profile of these recent technologies and providing vital proof of concept work. Molecular taxonomy, bacterial source tracking and pre-screening of chemicals for potential toxicities were all viewed as areas in which omics and molecular techniques could have immediate value, with the aim of reducing cost, increasing efficiency and providing more comprehensive data of improved quality.     

Sorption and predicted mobility of herbicides in Baltic soils

This study was undertaken to determine sorption coefficients of eight herbicides (alachlor, amitrole, atrazine, simazine, dicamba, imazamox, imazethapyr, and pendimethalin) to seven agricultural soils from sites throughout Lithuania. The measured sorption coefficients were used to predict the susceptibility of these herbicides to leach to groundwater. Soil-water partitioning coefficients were measured in batch equilibrium studies using radiolabeled herbicides. In most soils, sorption followed the general trend pendimethalin > alachlor > atrazine～ amitrole～ simazine > imazethapyr > imazamox > dicamba, consistent with the trends in hydrophobicity (log K_ow) except in the case of amitrole. For several herbicides, sorption coefficients and calculated retardation factors were lowest (predicted to be most susceptible to leaching) in a soil of intermediate organic carbon content and sand content. Calculated herbicide retardation factors were high for soils with high organic carbon contents. Estimated leaching times under saturated conditions, assuming no herbicide degradation and no preferential water flow, were more strongly affected by soil textural effects on predicted water flow than by herbicide sorption effects. All herbicides were predicted to be slowest to leach in soils with high clay and low sand contents, and fastest to leach in soils with high sand content and low organic matter content. Herbicide management is important to the continued increase in agricultural production and profitability in the Baltic region, and these results will be useful in identifying critical areas requiring improved management practices to reduce water contamination by pesticides.     

The chemical stability of formulations of some hydrolyzable insecticides in aqueous mixtures with hydrolysis catalysts

Abstract

The active ingredients in commercial formulations of malathion, oxamyl, carbaryl, diazinon, and chlorpyrifos diluted to “spray tank”; concentrations with buffered distilled or natural water of pH 4–9 were stable for at least 24 hr. Formulations of trichlorfon were not stable at pH 7 or above but disappearance rates were slower than for the pure chemical in homogeneous solution. Cupric ion was observed to be an effective catalyst for the hydrolysis of a variety of pure organophosphorus insecticides but did not catalyze hydrolysis of the active ingredients of the formulations examined. Increasing the dilution of the formulation increased the susceptibility of malathion, oxamyl, and carbaryl to hydrolysis.