太原市集中供热管网循环水中有害微生物的研究*

调查了山西太原市集中供热循环水系统中主要造成管网腐蚀的有害微生物,包括粘液异养菌、 硫酸盐还原菌、铁细菌、真菌;测定了各菌群的数量分布、类型及与水温之间的关系。结果表明：在管 网供热期间,循环水中有害菌菌数普遍低于管网腐蚀的菌数指标;停止供热期间,循环水中菌数超 标,对管网造成一定的腐蚀。     

炼油厂循环冷却水系统中有害微生物的研究

调查了我国十六个主要炼油厂循环冷却水系统中主要引起污损、腐蚀的有害微生物——形成粘液异养菌、硫酸盐还原菌、铁细菌、真菌的数量及类型;探讨了菌数量和污损危害的相关性,从而提出了炼油厂循环冷却水有害菌控制指标：粘液异养菌<105／ml,硫酸盐还原菌<102／ml,铁细菌<103／ml,真菌相似文献   

循环水中影响十二烷基二甲基苄基氯化铵杀菌作用的因素

季胺盐在医学上作为清洁消毒剂早巳为人们所熟知,曾密切结合致病菌类做了影响其消毒杀菌效果因素的研究。然而关于工业循环冷却水系统中应用于控制腐蚀危害微生物有关影响因素,却很少见到报道。为了控制工业循环水中微生物造成的腐蚀危害,我们针对从循环水中分离的主要腐蚀危害菌——硫酸盐还原菌、铁细菌及形成粘液的异养菌,筛选到了高     

虾-贝-红树林耦合循环水养殖系统中微生物群落分析

海水循环水养殖系统是重要的生态养殖模式发展趋势之一, 为了深入了解循环水养殖生态系统, 通过对系统各功能区水体中细菌16S rRNA基因V4V5区进行高通量测序和生物信息学分析, 从微生物生态学角度分析了循环水养殖系统不同功能区的细菌群落结构动态。测序分析结果显示, 海水循环水养殖系统中优势细菌种群分别属于变形菌门(Proteobacteria)、蓝藻门(Cyanobacteria)、拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)、放线菌门(Actinobacteria)和浮霉菌门(Planctomycetes)。红树林湿地水体中变形菌门和厚壁菌门丰度较高, 而对虾养殖池的拟杆菌门和浮霉菌门丰度较高。在不同优势类群中, 变形菌门多样性指数平均值最高, 其次是拟杆菌门, 厚壁菌门最低。在各功能区中, 红树林细菌多样性最高, 虾池最低。MDS分析结果显示虾池、贝池和红树林湿地水体中细菌群落结构有明显差异, 虾池与其他功能区差异最大。研究表明, 高密度对虾养殖对虾池水体中细菌群落有显著影响, 但其影响在循环水养殖系统后续功能区中逐渐减弱。     

包装木箱霉变菌的分离及防霉剂的筛选

木材含有多种有机物质。当温度和湿度等外界条件适宜时,微生物就会在木材及其制品上生长繁殖,产生代谢产物及有害毒素,腐蚀和破坏木材。为解决这一问题,本文报道包装木箱霉变菌的采样、分离与鉴定结果和抗菌药剂的筛选。     

微生物腐蚀及腐蚀机理研究进展

在不同的环境中,不同种类的微生物能在材料上附着繁殖,其生命活动会引起或加剧材料的腐蚀。根据种类及功能的不同,腐蚀微生物可以分为硫酸盐还原菌、硫氧化菌、产酸菌、铁氧化细菌、铁还原细菌、硝酸盐还原菌以及产粘液细菌等。微生物腐蚀几乎能使所有现用的材料受到严重影响,破坏材料的结构与性能,在建筑、运输管道、工业环境(石油化工等)以及海洋环境中造成巨大的安全隐患和财产损失。本文概述了目前发现的腐蚀相关微生物的类群和特性,以及相对应的微生物腐蚀机理,为防护和控制材料的微生物腐蚀提供理论指导。     

新型杀菌剂Biosperse XD3899在循环水系统中微生物控制的性能评估

清洁的系统表面对循环水系统的正常运行至关重要。生物粘泥的大量繁殖会产生严重的系统问题,使管道堵塞,换热器的换热效率下降,水质恶化,引起管道垢下腐蚀,而这些问题都将导致系统维护费用增加,运行成本提高,并直接降低了系统寿命。生物粘泥的控制措施除定时排污外,投加杀菌剂是去除生物粘泥最为直接有效的方法。常规的氧化型杀菌剂易受循环水中有机物料、阻垢缓蚀剂等的影响和干扰,使之杀菌效果降低;而非氧化型杀菌剂虽然不易受物料影响,但是由于大部分非氧化型杀菌剂使用成本较高,再者,长期大量使用容易产生抗药性,使之杀菌效果降低。本文着重介绍了对生物粘泥具有极强的剥离作用,同时可有效抑制生物粘泥再生的一种新型弱氧化型杀菌剂Biosperse XD3899。通过实验室模拟、现场应用,对其剥离以及抑制性能进行了评估。实验结果显示,Biosperse XD3899在高有机物料水体中对活菌数的控制效果远远高于常规的氧化型及非氧化型杀菌剂,可有效抑制生物粘膜形成;同时,对于系统中已经形成的生物粘泥具有很好的剥离效果。     

有机溶剂耐受菌的研究进展

有机溶剂耐受菌是一类新的能与有害影响因素竞争并能在有机溶剂中茁壮生长的微生物。介绍了有机溶剂对细菌的毒性机理,有机溶剂耐受菌的获得方法,讨论了有机溶剂耐受菌的两种反应形式,并对有机溶剂耐受菌的应用进行了展望。     

45份活性乳酸菌饮料微生物指标检测结果的分析

目的：对辽宁21家生产企业生产的活性乳酸菌饮料进行了微生物指标检测结果的分析。方法：共采集活性乳酸菌饮料45份,对其进行了乳酸菌数、大肠菌群数、致病菌、霉菌及酵母菌的测定,并对霉菌及酵母菌的菌相进行了分析。结果：17份样品乳酸菌数未达到食品卫生国家标准的要求,合格率为62.22%,有5份样品的霉菌数及4份样品的酵母数超过了食品卫生国家标准的要求,霉菌及酵母菌的合格率分别为88.89%、91.11%。本次调查共检出霉菌280株,占比例较大的是青霉、曲霉、镰刀菌、木霉、毛霉等,其中大部分可产生对人体有害的霉菌毒素。检出酵母菌1240株,主要为汉逊酵母、红酵母。结论：45份活性乳酸菌饮料中乳酸菌数合格率是比较低的。乳酸菌数量对产品质量优劣起着重要的作用,因此,通过对乳酸菌的分离培养与计数技术经常检测其活性是非常必要的。     

以聚羟基丁酸戊酸共聚酯为碳源去除循环水养殖系统的硝酸盐及生物膜中微生物群落动态

【目的】利用聚羟基丁酸戊酸共聚酯(PHBV)作为固体碳源和生物膜载体,去除循环水养殖系统的硝酸盐,并研究固体碳源反硝化反应器不同运行阶段生物膜中微生物群落结构的动态变化。【方法】采用PCR-DGGE技术对反硝化反应器中微生物群落结构的动态变化进行了分析,采用传统纯培养方法分离反应器中降解PHBV的细菌。【结果】连接固相反硝化反应器能使循环水养殖系统中积累的硝酸盐显著降低,并维持在较低水平(小于10 mg/L),而常规循环水养殖系统中硝酸盐浓度持续增加。系统发育树聚类分析结果表明,反硝化反应器生物膜细菌归属于变形菌门(β-proteobacteria、γ-proteobacteria和δ-proteobacteria)、厚壁菌门(Firmicutes)和拟杆菌门(Bacteroidetes)。反应器运行初期(40 d)的优势种群主要为Acidovorax和Bacillus;运行后期(150 d)的优势种群依次为Clostridium、Desulfitobacterium、Dechloromonas、Pseudoxanthomonas和Flavobacterium。从反应器中分离到的PHBV降解菌株分别归属于Acidovorax、Methylibium、Pseudoxanthomonas和Dechloromonas。【结论】利用PHBV为碳源能有效去除循环水养殖系统的硝酸盐。明确了反硝化反应器在运行过程中,碳源表面生物膜的优势菌群及其动态变化。     

Heatable carbon nanotube composite membranes for sustainable recovery from biofouling

Membrane filtration is one of the most reliable methods for water treatment. However, wider application is limited due to biofouling caused by accumulation of microorganisms on the membrane surface. This report details a heatable carbon nanotube composite membrane with self-cleaning properties for sustainable recovery from biofouling. Microfiltration polycarbonate/carbon-nanotubes hybrid membranes were fabricated using drawable nanotubes that maintained the porosity and provided electrical conductivity to the membrane. Less than 25 V potential and 2–3 W power increase membrane temperature to 100°C in ~10 s. This temperature is above what most microbial life, bacteria and viruses can handle. When this membrane was employed, filtered Escherichia coli collected on its surface were successfully annihilated within 1 min. Ohmic heating of this membrane could be an effective solution to combat biofouling and complications associated with membrane-based filtration. This is a novel and highly desirable approach to combat biofouling, due to its simplicity and economic advantage.     

Microbial biofilm formation and contamination of dental-unit water systems in general dental practice

Dental-unit water systems (DUWS) harbor bacterial biofilms, which may serve as a haven for pathogens. The aim of this study was to investigate the microbial load of water from DUWS in general dental practices and the biofouling of DUWS tubing. Water and tube samples were taken from 55 dental surgeries in southwestern England. Contamination was determined by viable counts on environmentally selective, clinically selective, and pathogen-selective media, and biofouling was determined by using microscopic and image analysis techniques. Microbial loading ranged from 500 to 10(5) CFU. ml(-1); in 95% of DUWS water samples, it exceeded European Union drinking water guidelines and in 83% it exceeded American Dental Association DUWS standards. Among visible bacteria, 68% were viable by BacLight staining, but only 5% of this "viable by BacLight" fraction produced colonies on agar plates. Legionella pneumophila, Mycobacterium spp., Candida spp., and Pseudomonas spp. were detected in one, five, two, and nine different surgeries, respectively. Presumptive oral streptococci and Fusobacterium spp. were detected in four and one surgeries, respectively, suggesting back siphonage and failure of antiretraction devices. Hepatitis B virus was never detected. Decontamination strategies (5 of 55 surgeries) significantly reduced biofilm coverage but significantly increased microbial numbers in the water phase (in both cases, P < 0.05). Microbial loads were not significantly different in DUWS fed with soft, hard, deionized, or distilled water or in different DUWS (main, tank, or bottle fed). Microbiologically, no DUWS can be considered "cleaner" than others. DUWS deliver water to patients with microbial levels exceeding those considered safe for drinking water.     

Microbial challenges for domestic heating oil storage tanks

Microbial growth on hydrocarbons is common in nature and used in bioremediation of contaminated sites, whereas in fuel storage tanks this phenomenon can affect the stability of the fuel and the tank. The impact of microbial growth and produced metabolites on materials, which are used in the construction of storage tanks, were analyzed. In contrast to metal tank components, polymeric materials did not affect or were influenced by microorganisms. Zinc was highly corroded by microbial growth, most likely due to the formation of organic acids that were produced during microbial growth on hydrocarbons. A contaminated water phase in a storage tank of a heating system was simulated with a self‐constructed pump test bench. Microbial growth began in the water phase of the storage tank and microbes were distributed throughout the tank system, through water‐in‐oil microemulsions. No microbial growth was observed in oil that was previously contaminated, indicating that essential nutrients had been depleted. The identification and removal of these essential nutrients from fuels could minimize or prevent microbial contamination. The results are discussed with regard to developing recommendations for the design and operation of domestic heating oil storage tanks to lower the risk of technical failure due to microbial contamination.     

Monitoring Microbial Community Composition by Fluorescence In Situ Hybridization During Cultivation of the Marine Cold-Water Sponge Geodia barretti

To determine the stability and specificity of microbes associated with the marine cold-water sponge Geodia barretti during cultivation, we compared the microbial community of freshly retrieved specimens to that of cultivated explants by fluorescence in situ hybridization (FISH). G. barretti hosts a specific homogeneous microbial community in its mesohyl, which is maintained during a cultivation period of 8 months. In 10-day-old explants, bright colonies of unusually large bacterial cells, located predominantly at canal walls, were observed in addition to the common bacteria. Bacteria of the aberrant type included both lineages present in whole sponges and foreign ones, notably numerous genera of sulfate-reducing bacteria. We assume that these represent infectious bacteria that eluded the innate immune system of the sponge. Explants that resist these microbial attacks during the critical phase of cultivation eliminate infectious bacteria. The intrinsic microbial community of G. barretti is not affected by these infections and remains persistent over a cultivation period of at least several months.     

Microbial community structure and biomass in developing drinking water biofilms

Traditional techniques to study microbes, such as culturable counts, microbial biomass, or microbial activity, do not give information on the microbial ecology of drinking water systems. The aim of this study was to analyze whether the microbial community structure and biomass differed in biofilms collected from two Finnish drinking water distribution systems (A and B) receiving conventionally treated (coagulation, filtration, disinfection) surface water. Phospholipid fatty acid methyl esters (PLFAs) and lipopolysaccharide 3-hydroxy fatty acid methyl esters (LPS 3-OH-FAs) were analyzed from biofilms as a function of water residence time and development time. The microbial communities were rather stabile through the distribution systems, as water residence time had minor effects on PLFA profiles. In distribution system A, the microbial community structure in biofilms, which had developed in 6 weeks, was more complex than those grown for 23 or 40 weeks. The microbial communities between the studied distribution systems differed, possibly reflecting the differences in raw water, water purification processes, and distribution systems. The viable microbial biomass, estimated on the basis of PLFAs, increased with increasing water residence time in both distribution systems. The quantitative amount of LPS 3-OH-FAs increased with increasing development time of biofilms of distribution system B. In distribution system A, LPS 3-OH-FAs were below the detection limit.     

Microbial activity in drinking water-associated biofilms

Microbial biofilms from surfaces in contact with water may play a beneficial role in drinking water treatment as biological filters. However, detrimental effects such as biofouling (i.e., biocorrosion and water quality deterioration) may also occur. In this study microbiological processes and factors influencing the activity of bacteria in biofilms were investigated by conventional cultivation methods. The presence of bacteria belonging to different ecophysiological groups was assessed during drinking water treatment, in biofilms developed on concrete, steel and sand surfaces. Influences of the treatment process, type of immersed material and physico-chemical characteristics of raw/bulk water and biofilms upon the dynamics of bacterial communities were evaluated. Results revealed intense microbial activity in biofilms occurring in the drinking water treatment plant of Cluj. Ammonification, iron reduction and manganese oxidation were found to be the predominant processes. Multiple significant correlations were established between the evolution of biofilm bacteria and the physico-chemical parameters of raw/ bulk water. The type of immersed material proved to have no significant influence upon the evolution of microbial communities, but the treatment stage, suggesting that the processes applied restrict microbial growth not only in bulk fluid but in biofilms, too.     

Mechanism of biofilm formation on a hydrophobic polytetrafluoroethylene membrane during the purification of surface water using direct contact membrane distillation (DCMD), with especial interest in the feed properties

Abstract

The impact of feed water quality on biofilm formation during membrane distillation (MD) was investigated in this study, particularly emphasizing the interrelationship between organics, salts, and microbes. Two types of typical natural surface waters in Nanjing, China, were chosen as feed solutions for long-term MD operation, including the Qinhuai River and Xuanwu Lake. The biofilms that developed under different feed water qualities exhibited distinct Foulant compositions and structures, causing different flux decline trends for the MD system. Accordingly, two typical patterns of biofilm formation were suggested for the MD operation of the two different kinds of surface waters in this study. Organics from a primal feed solution and dead bacteria were the key to the establishment of a biofilm on the membrane, and this needs to be effectively removed from the MD system through pre-treatment and process control strategies. Finally, a feasible strategy for MD biofouling control was suggested.     

Comparison of free-living and particle-associated bacterial communities in a coastal Lagoon

We analyzed, by terminal restriction fragment length polymorphisms (T-RFLPs) of PCR-amplified 16S rDNA, microbial diversity in water collected during the dry and wet seasons in a human-impacted coastal lagoon. Water samples were fractionated by prefiltration to differentiate particle-associated and free-living microbes. From a sample collected during the dry season, prefiltration removed 23 to 44% of bacteria, as assessed by direct counts and MPN, and 99% of phytoplankton, as assessed by chlorophyll a. Restriction with RsaI yielded fewer peaks than restriction with HhaI. Diversity indices calculated from T-RFLPs were higher in the lagoon than adjoining coastal waters and higher in the particle-associated than the free-living fraction. In the dry season, peaks found only in bulk and particle-associated T-RFLPs were consistent with plastid and cyanobacterial ribotypes. These peaks matched those observed in the sequence of a clone generated from the bulk fraction with plastid and cyanobacterial specific primers. This clone appeared related to plastids found in the diatom genus Skeletonema. Principal component analysis of T-RFLPs suggested that the difference between the free-living and particle-associated fractions in the dry season was less than temporal variability in this lagoon and that these fractions varied significantly only in the wet season. This fractionation of microbial populations into particle-associated and free-living guilds during the wet season, when water residence time in the lagoon is relatively low, suggests an external source of particle-associated bacteria such as erosion of upland soils by runoff.     

Partial incubation during egg laying reduces eggshell microbial loads in a temperate‐breeding passerine

Incubation prior to clutch completion may be adaptive if it maintains egg viability by inhibiting eggshell microbial growth, thus reducing the likelihood that the embryo becomes infected. To test this hypothesis, we examined the effect of partial incubation during egg laying on eggshell microbial loads in eastern bluebirds Sialia sialis breeding at a temperate‐zone site. We sampled eggshell microbes prior to and following four days of exposure to either partial incubation during the laying period or ambient environmental conditions without incubation (experimental eggs). Microbial colony counts declined significantly for eggs left in the nest during the laying period but did not vary significantly for eggs exposed to ambient conditions. Initial microbial loads were more similar to those previously reported from tropical than temperate environments, and microbes from potentially pathogenic groups were detected on 88% of first‐laid eggs on the day of laying. Egg viability was maintained when eggs were held indoors for four days without incubation but declined sharply thereafter. Our results suggest that partial incubation during egg laying may enhance egg viability in eastern bluebirds by reducing eggshell microbial loads; these effects appear stronger than those usually reported from the temperate zone.