Bacterial community structure analyses to assess pollution of water and sediments in the Lake Shkodra/Skadar, Balkan Peninsula

- Goal, Scope, Background. Lake Skadar is the largest lake in Balkan Peninsula, located on the Montenegro-Albanian border. The unique features of the lake and wide range of endemic and rare or endangered plant and animal species resulted in the classification of the Skadar as a wetland site of international significance. In spite of its importance the Lake is influenced by inflowing waters from river Morača and other regional rivers contaminated by the industry, municipal and agricultural activities in the area. Therefore, the Lake has been subject of various physical, chemical, biological and toxicological examinations. However, community-level analyses are most relevant to assess the effect of stressors on aquatic ecosystems. In the present study bacterial community structure among differently polluted sites of the lake was compared by genetic fingerprinting technique. Methods Water and sediment samples were collected from five differently polluted sampling sites on the Lake Skadar in spring and autumn of the same year. The bacterial community structure in the samples was characterized and compared by temporal temperature gel electrophoresis (TTGE) analysis of polymerase chain reaction-amplified bacterial 16S rRNA genes. Results and Discussion The TTGE analysis resulted in many distinguishable and reproducible band patterns, allowing reliable comparison of bacterial communities among sampling sites. Results on the bacterial community structure revealed that three of the selected locations can be considered as sites that have not shown any pollution degradation determined by our method, due to similar structure of bacterial community in the sediment samples. On the other hand, significant shifts in bacterial community structure in the mouth of the river Morača and Plavnica were shown. Since the results coincide with some of the bioassays and chemical analysis performed previously, the changes in bacterial community structure are explained as an effect of antropogenic pollution on the lake ecosystem by waters of river Morača and stream Plavnica. Conclusion The TTGE has proven to be an efficient and reliable method to monitor bacterial dynamics and community shifts in aquatic environment, especially in the sediments. Within the variety of environmental quality assessments the use of TTGE analyses of bacterial community is strongly recommended, particularly as an initial investigation. However, in any conclusion on the state of the environment, the TTGE results should be combined to some other biological, chemical and hydrological data. Recommendation and Outlook Since prokaryotes are a crucial group of organisms in the biosphere, the ecosystem function studies are largely based on bacterial communities. Therefore, bacterial community structure analysis should be a part of an integrated weight of evidence approach in pollution assessment. In case of Triad approach, consisting of chemical analyses, bioassays, and community studies in the field, the TTGE bacterial community structure analyses should be placed in the later Triad leg. In comparison to other community studies, based on various biotic indices, the TTGE bacterial community analysis has proven to be very sensitive, reliable and less time consuming.     

深海热液喷口周围微氧耐压细菌的培养研究

研究采用析因实验设计,探讨了培养基的水源、培养温度和生长pH等因素对喷口细菌生长繁殖的影响,初步探索了常压下东太平洋某海底喷口周围微氧耐压细菌的生长条件。样品培养10d后,对培养液中细菌量进行显微计数,实验数据用SPSS11.0统计软件中的方差分析程序进行处理。统计结果显示:在标准大气压下,从研究样品中获得最多细菌数的较优培养条件为:培养基水源为单蒸水;生长pH为7.60;培养温度为50℃。在该条件的培养液中细菌平均浓度达2.596×10个/mL。研究结果为进一步认识、鉴定与开发利用深海喷口周围细菌资源打下了基础。     

蛭石和沸石对番茄青枯病及土壤微生物的影响

施用沸石于番茄连作地，使番茄青枯病显著减少，但施用蛭石使番茄青枯病加重。施用沸石后土壤微生物生物量显著提高，而蛭石处理对土壤微生物生物量的影响不明显。沸石和蛭石都能提高土壤中真菌、细菌和放线菌的数量和土壤微生物活性，其中沸石处理的土壤高于蛭石处理的土壤。     

给水生物预处理反应器的细菌种群多样性和群落结构

提取一生产性规模的给水生物预处理反应器中生物膜样品的总DNA,构建细菌16S rDNA克隆文库,并通过16S rDNA序列的系统发育分析,对生物膜中的细菌种群多样性和群落结构进行了研究.实验结果表明,给水生物膜反应器中的细菌种群多样性十分丰富;生物膜中的细菌分别属于10个主要类群,其中α-Proteobacteria是克隆文库中的最大细菌类群,占克隆子总数的32.28%,其次是β-Proteobacteria;与Rhodobacter系统关系密切的细菌是克隆文库中所占比例最大的一个菌属,占克隆子总数的12.6%;反应器中与硝化作用有关的是Nitrosomonas和Nitrospira属的细菌.研究结果表明,给水生物预处理反应器中的细菌群落结构和废水生物处理反应器中的细菌群落结构是有所差异的.图1表1参13     

添加猪粪对不同施肥历史土壤细菌群落的影响

为探讨粪肥携带的微生物对土壤微生物的影响，以长期施用粪肥和化肥的土壤为研究对象，耦合传统微生物学培养方法和现代分子微生物学方法，分析了猪粪和灭菌猪粪对2种土壤的细菌数量、群落结构和热代谢活性的影响.结果表明，以9.0t/hm²的用量施入时，猪粪和灭菌猪粪对两种土壤中的可培养细菌数量以及细菌16S-rRNA拷贝数均无明显影响；土壤中的土著微生物对猪粪携带的外源细菌在土壤中定殖具有明显的抑制作用，将2种土壤灭菌后添加猪粪，可培养细菌平均数量较未灭菌土壤分别增加45.96和96.21倍.粪肥输入的化学物质未导致土壤细菌群落结构和相对丰度发生明显变化；而粪肥输入的外源细菌Marinilabiaceae、Porphyromonadaceae、Bacteroidale和Pseudomonadaceae则可以在长期施用化肥的土壤中定殖并对相应的细菌丰度造成影响，但是在长期施用粪肥的土壤中，这些细菌在最开始就被抑制.添加粪肥提高了长期施用化肥土壤的微生物热代谢活性，但对长期施用粪肥的土壤无明显影响.长期施用化肥的土壤受粪源细菌的影响较大，而长期施用粪肥的土壤对粪肥的敏感度降低，对粪肥携带的外源细菌的抑制作用增强.     

错流式动态膜-生物反应器中污泥活性的研究

应用错流式动态膜-生物反应器(CDMBR)对己内酰胺废水进行了180 d的实验,实验过程中测定反应器的膜出水和上清液的水质,并对污泥进行了耗氧呼吸速率测定.结果表明,上清液COD一直保持在100mg/L以下,而膜出水的则保持在50 mg/L以下,膜对上清液的COD去除率达50%,而对氮的去除没有贡献.可溶性细胞产物(SMP)在反应器内容易积累,停留足够的时间后能被生物降解.通过投加抑制剂测定耗氧呼吸速率,发现异养菌、硝化细菌和亚硝化细菌的活性由于F/M的降低和SMP积累受到一定的抑制,但不影响系统的处理效率.跨膜压力、膜面流速越大,通量衰减得也就越快.     

微生物法和微生物生态法的评价和选用

微生物法和微生物生态法作为生物治理方案的两大类型，已日益受到环保工作者的重视。这两种类型的治理方法各有特点，各有利弊。如何选择使用？主要取决于污染场所中污染形成的时间长短、污染程度、污染物浓度、污染物中是否含有污水、是否需要快速治理等。应明确指出的是，采用生物治理法虽可在多种情况下大大降低污染物的浓度，但从长远来看，还不能单纯依靠降低污染物的排放浓度，而是应从低浓度污染物对人和环境产生的长期影响着眼，制定出一套治理标准，这样才能准确评价生物治理技术在环境保护中所起的真正作用。     

EFFECTS OF SELECTED HERBICIDES ON BACTERIAL POPULATIONS IN NONTREATED AND TREATED WATER1

ABSTRACT: Bacterial populations in nontreated and herbicide-treated waters were subjected to three different herbicides. Diuron, dichlobenil, and diquat were added (100 mg/l) to water samples from two fresh water lakes and two herbicide-treated ponds. Total numbers of bacteria were monitored. Bacterial populations in fresh lake water decreased after herbicide additions; however, final populations were significantly greater than the controls. Similar observations were recorded for bacteria in dichlobenil- and diuron-treated waters. Selective enrichment is probably expressed in these experiments.     

Dynamics of Bacterial Abundance,Biomass, Activity,and Community Composition in the Oligotrophic Traunsee and the Traun River (Austria)

The holomictic Traunsee is the deepest and second largest lakein Austria. The special characteristic of this ecosystem isthe fact that local salt and soda industries presumably alterthe lake by the discharge of waste materials. Since thebeginning of the 20th century salt and soda works areannually releasing up to 50,000 tons of solid wastes and up to150,000 tons of chloride into Traunsee. To assess potentialeffects of these anthropogenic impacts on the bacterioplanktonthree sampling sites, influenced as well as not influenced bythe industrial discharge, were chosen for comparison andsampled monthly from November 1997 to October 1998. Bacterialabundance ranged between 0.4 to 3.0 × 10⁶ cells ml^-1 with decreasing numbers along the depth profile. Theproportion of actively respiring bacteria, i.e. INT [2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyltetrazolium chloride]reducing cells, never exceeded 10% of DAPI (4',6'-diamidino-2-phenylindole) stained cells. Fluorescence in situ hybridization (FISH) was used to examine the seasonal and spatial distribution of dominant phylogenetic groups of thebacterioplankton. Up to 84% of bacteria detected with DAPIcould be detected via FISH applying the universal bacterialprobe EUB338. Percentages of alpha- and beta-Proteobacteriaand members of the Cytophaga-Flavobacterium cluster did notexceed 60% of DAPI-stained cells.Beta-Proteobacteriaappeared to be the most abundant group, not only in Traunsee butalso in two reference lakes, Attersee and Hallstättersee. No significant differences in any of the bacterial parameters couldbe detected between the three sampling sites and all measurementswere found in the range reported for oligotrophic lakes. The highdischarge of the Traun River, resulting in a lake water renewaltime of only one year, may diminish possible effects of industrial waste discharge in the pelagic zone.     

Microbial response to CaCO3 application in an acid soil in southern China

Calcium carbonate (CaCO₃) application is widely used to ameliorate soil acidification. To counteract soil and bacterial community response to CaCO₃ application in an acidic paddy soil in southern China, a field experiment was conducted with four different dosages of CaCO₃ addition, 0, 2.25, 4.5 and 7.5?tons/ha, respectively. After one seasonal growth of rice, soil physicochemical properties, soil respiration and bacterial communities were investigated. Results showed that soil pH increased accordingly with increasing dose of CaCO₃ addition, and 7.5?tons/ha addition increased soil pH to neutral condition. Moderate dose of CaCO₃ application (4.5?tons/ha) significantly increased soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) content, enhanced soil respiration, while the excessive CaCO₃ application (7.5?tons/ha) decreased these soil properties. High-throughput sequencing results illustrated that moderate dose of CaCO₃ application increased the richness and alpha diversity of soil bacterial community. Compared with control, the relative abundance of Anaerolineaceae family belonging to Chloroflexi phylum increased by 38.7%, 35.4% and 24.5% under 2.25, 4.5 and 7.5?tons/ha treatments, respectively. Redundancy analysis (RDA) showed that soil pH was the most important factor shaping soil bacterial community. The results of this study suggest that proper dose of CaCO₃ additions to acid paddy soil in southern China could have positive effects on soil properties and bacterial community.