一株溴氰菊酯降解菌的分离鉴定及其降解条件优化

【背景】拟除虫菊酯类农药的降解已成为食品安全和环境卫生领域的研究热点,而生物降解被认为是一种绿色高效的解决方法。【目的】从长期受拟除虫菊酯类农药污染的草莓根系土壤分离一株溴氰菊酯(deltamethrin,DM)降解菌,并优化其培养基及降解条件,从而提高DM降解菌的降解效率。【方法】采用富集驯化、分离纯化法筛选DM降解菌,通过形态学和生理生化特征,以及16S rRNA基因序列分析进行鉴定。通过Plackett-Burman因素筛选试验、最陡爬坡试验和Box-Behnken试验优化菌株降解条件。【结果】筛选获得一株DM降解菌LH-1-1,96h对DM(100mg/L)的降解率为53.43%,经鉴定为琼氏不动杆菌(Acinetobacter junii);通过优化后,在DM浓度75mg/L、胰蛋白胨3 g/L、pH值6.8、硫酸铵1.5 g/L、氯化铁0.01 g/L、接种量为5%(体积比)、菌龄12 h、培养温度30℃条件下,菌株LH-1-1对DM降解率达82.36%,较未优化前提高了28.93%。【结论】A. junii LH-1-1具有较高的DM降解能力,该菌可为生物修复受DM或拟除...     

污水短程硝化体系氨氧化菌与亚硝酸盐氧化菌的生态学研究进展

短程硝化(partial nitrification, PN)是一种绿色低碳的生物脱氮创新技术,伴随厌氧氨氧化(anaerobic ammonia oxidation, Anammox)污水脱氮技术的进一步推广,短程硝化作为提供其电子受体的重要环节,已成为了污水脱氮领域的研究热点。氨氧化菌(ammonia-oxidizing bacteria,AOB)和亚硝酸盐氧化菌(nitrite-oxidizing bacteria, NOB)是该技术的核心竞争微生物,掌握这两类微生物的生态学特征,借助生态学理论和手段调控AOB淘汰NOB,提高种群的可预测性,对于实现稳定高效的短程硝化具有重要意义。本文基于生态学角度介绍了AOB和NOB基础分类、生理性能及生态位分离,重点综述了短程硝化系统中AOB和NOB的生长动力学、群落构建、环境因素和相互作用,最后对这两类微生物的未来研究重点和研究方法进行了展望,为短程硝化工艺的快速启动和稳定运行提供理论指导。     

High tolerance of methanogens in granular sludge to oxygen

This research assessed the effect of oxygen exposure on the methanogenic activity of anaerobic granular sludges. The toxicity of oxygen to acetoclastic methanogens in five different anaerobic granular sludges was determined in serum flasks with effective gas-to-liquid volumes of 4.65 to 1. The amount of oxygen that caused 50% inhibition of the methanogenic activity after 3 days of exposure ranged from 7% to 41% oxygen in the head space. These results indicate that methanogens located in granular sludge have a high tolerance for oxygen. The most important factor contributing to the tolerance was the oxygen consumption by facultative bacteria metabolizing biodegradable substrates. Uptake of oxygen by these bacteria creates anaerobic microenvironments where the methanogenic bacteria are protected. The results also indicate that methanogens in sludge consortia still have some tolerance to oxygen, even in the absence of facultative substrate for oxygen respiration. (c) 1993 John Wiley & Sons, Inc.     

Enhanced biological treatment of saline wastewater by using halophilic bacteria

Biological treatment of saline wastewater by conventional activated sludge culture usually results in low removal of chemical oxygen demand (COD) because of plasmolysis of the organisms at high salt concentrations. Since salt removal operations by physicochemical processes before biological treatment are costly, a salt-tolerant organism (Halobacter halobium) was used for effective biological treatment of saline wastewater in this study. Halobacter halobium was used in activated sludge culture for COD removal from saline wastewater (1–5% salt) by fed-batch operation of an aeration tank. Inclusion of Halobacter halobium into activated sludge culture improved the rate and extent of COD removals especially with salt above 2% (w/v).     

Algal photosynthetic aeration increases the capacity of bacteria to degrade organics in wastewater

Wastewater treatment is an energy-intensive process and a net emitter of greenhouse gas emissions. A large fraction of these emissions is due to intensive aeration of aerobic bacteria to facilitate break-down of organic compounds. Algae can generate dissolved oxygen at levels in excess of saturation, and therefore hold the potential to partially displace or complement mechanical aeration in wastewater treatment processes. The objective of this study was to develop an internally consistent experimental and modeling approach to test the hypothesis that algal photosynthetic aeration can speed the removal of organic constituents by bacteria. This framework was developed using a simplified wastewater treatment process consisting of a model bacteria (Escherichia coli), a model algae (Auxenochlorella protothecoides), and a single carbon source that was consumable by bacteria only. This system was then tested both with and without the presence of algae. A MATLAB model that considered mass transfer and biological kinetics was used to estimate the production and consumption of O₂ and CO₂ by algae and bacteria. The results indicated that the presence of algae led to 18–66% faster removal of COD by bacteria, and that roughly one-third of biochemical oxygen demand was offset by algal photosynthetic aeration.     

Ammonium exchange and bioregeneration of bio-flocculated zeolite in a sequencing batch reactor

Natural zeolite was added to the sequencing batch reactors to assess its role in ammonium exchange. Even though the biofilm was fully developed on the zeolite surface, ammonium removal and the biological regeneration of the zeolite occurred constantly during the anoxic-fill phase and the reaction phase, respectively. However, the specific nitrification rate of the bio-flocculated zeolite was lower than that observed in the control on account of the limited ammonium release to the liquid phase.     

Reconsidering the use of photosynthetic bacteria for removal of sulfide from wastewater

The feasibility of using photosynthetic sulfide-oxidizing bacteria to remove sulfide from wastewater in circumstances where axenic cultures are unrealistic has been completely reconsidered on the basis of known ecophysiological data, and the principles of photobioreactor and chemical reactor engineering. This has given rise to the development of two similar treatment concepts relying on biofilms dominated by green sulfur bacteria (GSB) that develop on the exterior of transparent surfaces suspended in the wastewater. The GSB are sustained and selected for by radiant energy in the band 720-780 nm, supplied from within the transparent surface. A model of one of these concepts was constructed and with it the reactor concept was proven. The dependence of sulfide-removal rate on bulk sulfide concentration has been ascertained. The maximum net areal sulfide removal rate was 2.23 g m-(2) day-(1) at a bulk sulfide concentration of 16.5 mg L(-1) and an incident irradiance of 1.51 W m(-2). The system has a demonstrated capacity to mitigate surges in sulfide load, and appears to use much less radiant power than comparable systems. The efficacy with which this energy was used for sulfide removal was 1.47 g day(-1) W(-1). The biofilm was dominated by GSB, and evidence gathered indicated that other types of phototrophs were not present.     

变性梯度凝胶电泳在环境微生物生态学中的应用

PCR-变性梯度凝胶电泳(PCR-DGGE)具有可靠性强、重复性好、方便快捷等优点,已被广泛应用于环境生态学中微生物群落多样性、动态性分析和功能细菌的跟踪。本文综述了PCR-DGGE技术的基本原理,不同DNA提取方法的比较,不同PCR方式的比较及其在环境生态学中研究微生物群落多样性、环境中微生物群落变化的动态监测、硝化菌-反硝化菌和硫酸还原菌(SRB)的动态分析和监测等领域中的应用,并对该技术自身存在的局限性和应用前景进行了评价。     

Aeration conditions affecting growth of purple nonsulfur bacteria in an organic wastewater treatment process

Effects of aeration on purple nonsulfur bacteria (PnSB) were studied in photobioreactors. Bacterial community changes were analyzed by denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH). DGGE band pattern change was small and only few prominent bands were obtained at non-aeration condition. Sequencing results of the prominent DGGE bands obtained at this condition revealed that they represented mainly the PnSB, Rhodobacter sphaeroides and Rhodopseudomonas palustris. On the other hand, under aerated condition, some prominent bands originated from heterotrophs appeared but no proliferation of PnSB was observed. FISH was applied to detect PnSB and their population was quantified. Maximum PnSB ratio (up to 80%) was obtained both at non-aeration condition and at constant ORPs less than -200 mV. In the presence of DO, Rps. palustris was more competitive to chemoheterotrophs than Rb. sphaeroides.     

Biodeterioration of natural stone with special reference to nitrifying bacteria

An evaluation of field data from historical buildings in Germany showed that chemoorganotrophic bacteria are the most numerous microorganisms in building stones, followed by fungi and nitrifying bacteria. Chemoorganotrophic bacteria and fungi were present in almost every sample. Ammonia and nitrite oxidizers were found in 55 and 62% of the samples, respectively. Within months, natural stone was colonized by chemoorganotrophic microorganisms. The highest cell numbers were usually found near the surface. The colonization of natural stone by nitrifying bacteria took several years. The highest cell numbers were in some cases found underneath the surface. Nitrifying bacteria showed a preference for calcareous material with a medium pore radius between 1 and 10 m. Cell numbers of nitrifying bacteria did not correlate to the nitrate content of the stone material. We demonstrated that the stone inhabiting microflora can cause significant loss of nitrate by denitrification. Our data strongly suggested that microbial colonization of historical buildings was enhanced by anthropogenic air pollution. Samples taken from stone material with a pore radius 1 m had significantly higher cell numbers when they were covered with black crusts. A comparison of samples taken between 1990–1995 from buildings throughout Germany showed that in eastern Germany a significantly stronger colonization with facultatively methylotrophic bacteria and nitrifying bacteria existed. The same was true for natural stone from an urban exposure site when compared to material from a rural exposure site. Data from outdoor exposure and laboratory simulation experiments indicated that the colonization of calcareous stone by nitrifying bacteria was enhanced by chemical weathering.     

硫酸盐还原细菌生物被膜的形成与调控研究进展

硫酸盐还原细菌(sulfate-reducing bacteria,SRB)形成的生物被膜是微生物导致金属锈蚀行为的主要原因,同时也是重金属污水微生物修复技术的关键因子。生物被膜形成及调控机制研究对SRB的防治和利用均十分重要。本文综述了近年来SRB生物被膜的研究进展,包括SRB生物被膜的胞外多聚物组成和控制因子,并着重阐述了目前已知的调控因子对SRB生物被膜形成的影响。     

两株溶藻细菌的分离及初步研究

选择藻华现象严重的巢湖作为采样点,取3个不同位置的水样通过0.22μm的纤维滤膜过滤,培养后加入适应期的藻液中,取黄化藻液作为分离菌种的材料,初筛菌株经反复试验获得有较强抑藻能力的菌株,经生理生化鉴定及16S rDNA分子鉴定其种属。初筛得到45个菌株,有两个菌株WD1和WD2表现出溶藻作用。两株细菌的菌液经离心、高温灭菌、细胞破碎等处理对供试藻鱼腥藻也均有不同程度的抑制作用。分离得到两株溶藻细菌,WD1为约氏不动杆菌,WD2为门多萨假单胞菌。     

Isolation,identification and growth conditions of photosynthetic bacteria found in seafood processing wastewater

Four photosynthetic bacteria, isolated from 14 samples taken from seafood processing plants, were identified as species of Rhodocyclus gelatinosus, belonging to the purple, non-sulphur bacteria of the family Rhodospirillaceae. Cultivation in synthetic medium under four different conditions indicated that all four strains gave maximum carotenoid and bacteriochlorophyll synthesis under anaerobic conditions in the light, with values of 11 to 12.6 and 102 to 108 mg/g dry cell wt, respectively. These values are 87% higher than the pigment content obtained from aerobic cultivation, although the cell biomass of all strains (1.7 to 2.3 g/l) was 22 to 38% higher under aerobic conditions. Protein content was always between 32 and 43%. The specific growth rates of all isolates in aerobic cultivation (0.04 to 0.06 h^-1) were twice those in anaerobic conditions in the light. No growth occurred in anaerobic conditions in the dark.     

亚硝酸盐氧化细菌的生态位以及对海洋环境变化的响应机制

硝酸盐是海洋微生物可利用氮的主要形式,也是限制表层海洋生物生产力的主要营养物质,海洋中的硝酸盐主要由氨和亚硝酸盐的氧化产生。探索亚硝酸盐氧化细菌在海洋生态系统中的生态位以及对环境变化的响应机制,对认识微生物参与的氮循环具有十分重要的意义。本文综述了海洋亚硝酸盐氧化细菌的研究进程及其主要种类,并总结了其主要的生理生态学特征,指出微生物在海洋生态系统变迁中所衍生出的适应对策。基于当前的研究现状,展望亚硝酸盐氧化细菌未来的研究方向,以期更好地了解海洋中亚硝酸盐的氧化过程,为进一步认识氮在生物地球化学中的循环奠定基础。     

Separation of BSA through FAU-type zeolite ceramic composite membrane formed on tubular ceramic support: Optimization of process parameters by hybrid response surface methodology and biobjective genetic algorithm

In this study, Faujasite (FAU) zeolite was coated on low-cost tubular ceramic support as a separating layer through hydrothermal route. The mixture of silicate and aluminate solutions was used to create a zeolitic separation layer on the support. The prepared zeolite ceramic composite membrane was characterized using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), particle size distribution (PSD), field emission scanning electron microscopy (FESEM), and zeta potential measurements. The porosity of ceramic support (53%) was reduced by the deposition of FAU (43%) zeolite layer. The pore size and water permeability of the membrane were evaluated as 0.179?µm and 1.62?×?10^?7?m³/m²?s?kPa, respectively, which are lower than that of the support (pore size of 0.309?µm and water permeability of 5.93?×?10^?7?m³/m²?s?kPa). The permeate flux and rejection potential of the prepared membrane were evaluated by microfiltration of bovine serum albumin (BSA). To study the influences of three independent variables such as operating pressure (68.94–275.79?kPa), concentration of BSA (100–500?ppm), and solution pH (2–4) on permeate flux and percentage of rejection, the response surface methodology (RSM) was used. The predicted models for permeate flux and rejection were further subjected to biobjective genetic algorithm (GA). The hybrid RSM-GA approach resulted in a maximum permeate flux of 2.66?×?10^?5?m³/m²?s and BSA rejection of 88.02%, at which the optimum conditions were attained as 100?ppm BSA concentration, 2 pH solution, and 275.79?kPa applied pressure. In addition, the separation efficiency was compared with other membranes applied for BSA separation to know the potential of the fabricated FAU zeolite ceramic composite membrane.     

Synergistic anti-biofouling effect of Ag-exchanged zeolite and D-Tyrosine on PVC composite against the clinical isolate of Acinetobacter baumannii

Due to their susceptibility to bacterial biofilm formation, commercial tubes for medical use are one of the main sources of hospital infections with Acinetobacter baumannii. The anti-biofouling activity of novel composites against the clinical isolate of the multi-drug resistant A. baumannii is reported here. The composites were prepared by addition of micronised silver-exchanged natural zeolite (Ag-NZ) into poly(vinyl chloride) (PVC), followed by coating of the composites with D-Tyrosine (D-Tyr). The Ag-NZ composites (containing 1–15 wt% of Ag-NZ) coated with D-Tyr (Ag-NZ-Tyr) showed a bactericidal effect (100% or a 6.9 log CFU reduction) towards immobilised bacterial cells. The uncoated Ag-NZ composites showed a reduction of up to 70% (4.4 log CFU) of immobilised bacteria in comparison with the original PVC. Rheological testing of the composites revealed that the addition of Ag-NZ slightly affected processability and formability of the PVC and increased the elasticity of the polymer matrix.     

印染废水脱色菌的选育及其生态特性的研究

1 前言 印染工业是太湖地区小城镇的一大工业部门。随着乡镇企业的发展,印染废水排放量逐年增加,已成为严重污染区域水环境的重点污染源之一。近年国内外报道了利用微生物对印染废水进行脱色处理的可能性,为了多途径寻找适合于乡镇企业印染废水的经济、高效的生物处理技术,本研究针对目前印染废水生物处理中的菌种适应性和作用范围问题,选育出一批对多种染料有降解作用的“土著”脱色菌,并对