光合细菌对致病弧菌的抑制作用

本文主要介绍5株光合细菌对3株致病弧菌的抑制作用研究,结果表明,在不同的培养基中其抑菌效果不同,在普通培养基中No.3PSB对副溶血弧菌和河弧菌有明显的抑制作用,但在TCBS培养基中,则无抑菌效果,在培养基I中,No.1和No.2 PSB对3株致病弧菌的抑制作用皆取得良好的效果。     

Abschätzung der Eignung einer molekularbiologischen Methode zur Charakterisierung der Grundwasserbiozönose

Assessing the Suitability of a Molecularbiological Method To Characterise the Microbial Populations in Groundwater A molecularbiological technique was used to characterise the bacterial community structure of groundwater habitats. This method consists of the isolation of bacterial DNA from the samples, amplification of 16S rDNA by PCR (polymerase chain reaction), and separation of the amplified DNA by DGGE (denaturing gradient gel electrophoresis). By using more specific primer combinations in the PCR instead of universal eubacterial primers, also groups of microorganisms (Proteobacteria, sulfate reducer, Archaea) were determined. The resulting DGGE patterns that reflect the microbial diversity are compared and differences or similarities evaluated. In the present studies, groundwater from different sites (bank filtrate, artificially recharged groundwater, and natural groundwater) and with changing redox milieus (aerobic, anaerobic) were investigated as well as the solid aquifer material. Besides, samples were taken from the different stages of artificial groundwater recharge, i.e., from surface water to the drain tile. Samples from groundwater derived from sites with different hydrogeochemical or hydrological conditions like bank filtrate and recharged groundwater revealed great differences in DGGE patterns indicating a characteristic species composition in these habitats, while samples taken at different times from the same groundwater showed only small seasonal variations. Clearly different patterns were also found for groundwater and the adjacent solid material as well as for anaerobic and aerobic groundwaters. Looking at artificial groundwater recharge, almost identical patterns were found in raw water and samples from gravel and sand filtration. DGGE patterns from the resulting groundwater indicated a total change in community structure during underground passage. By using group specific primers, Desulfovibrionaceae, Desulfobacteriaceae, and Archaea could be detected in anaerobic groundwaters.The molecularbiological approach described here gives an increasingly comprehensive and more precise picture of the microbial population of different environments. It is especially suitable to compare the community structure from different habitats or to analyse changes for example due to environmental stress at the same site.     

南沙海区沉积物中细菌和古细菌16S rDNA多样性的研究

采用细菌16SrDNA通用引物和PCR扩增等方法,构建了南海南沙海区沉积物16S rDNA文库,并通过RFLP酶切分型对所获得的70个克隆进行测序。从国际分子生物学数据库中调取相关序列,以PAUP4．0分析软件构建序列同源性矩阵和系统发育树图。结果表明,与细菌文库中克隆相似的微生物属于4个细菌类群：变形细菌(Proteobacteria)(60％)、革兰氏阳性细菌(Gram-positivre bacteria)(13％)、浮霉菌(Planetomycetes)(10％)和无硫绿细菌(Green nonsulfur bacteria)(6％),其中变形细菌(包括δ-、γ-和α-变形细菌)是明显的优势类群。采用Blast程序对所有序列基因数据库进行搜索,发现只有一个克隆与已知序列完全相似,说明文库具有极高的多样性。但是对古细菌文库中所获得的克隆子进行二级结构和序列特征分析的结果表明,这些克隆子均为海洋未获培养的细菌,因此在作者的文库中并未有古细菌的发现。     

Ecological Effects of Remote Smallsand Descending on Urban Area: Deduced from the "Mud - Snow" in Changchun City

IntroductionContinued sandstorms occurring in North Chinaeally this year have attracted close attention of manyscientists from different aspects. It is recorded thatserious sandstorms occurred eight times in China in1960' s, thirteen times in 1970, s, fou…     

来自大黄鱼(Pseudosciaena crocea)肠道的弧菌拮抗菌的筛选与鉴定

采用点种法并以副溶血弧菌(Vp1.2164)和溶藻弧菌(Va-Y)为弧菌指示菌,对从健康的大黄鱼肠道内分离的115株细菌进行体外拮抗试验。并对筛选出的拮抗菌进行抗菌谱测定,最后利用VITEK-32细菌快速鉴定系统和16SrRNA基因序列对拮抗菌进行鉴定。结果表明,从中筛选到3株有较强拮抗作用的菌株,编号分别为X1402-1、X1108和X3914,且菌株X1402-1的抗菌作用最强,抗菌谱最广,21株病原指示菌中,对16株均能产生较强的抑制作用,其中对Vp-1.2164的抑菌直径最大,达到28.5mm,对Va-Y的抑菌直径为8.7mm;其次为菌株X1108和X3914,对两种指示弧菌的抑菌直径分别为:12.0mm、9.0mm和0mm、7.2mm。经VITEK-32细菌快速鉴定系统鉴定,3株拮抗菌分别与铜绿假单胞菌,恶臭假单胞菌,地衣芽孢杆菌的相似性均为99%。通过16SrRNA基因序列分析表明,3株拮抗菌分别与类产碱假单胞菌Pseudomonas pseudoalcaligenes(EU419918)、恶臭假单胞菌Pseudomon asputida(FJ440105)和地衣芽孢杆菌Bacillus licheniformis(DQ988136)的16SrRNA基因同源性最高,分别为100.0%、97.5%、99.0%。综合分析试验结果,X1402-1、X1108和X3914分别被确定为类产碱假单胞菌、恶臭假单胞菌和地衣芽孢杆菌。     

Respiration partitioning in contrasting subtidal sediments: seasonality and response to a spring phytoplankton deposition

Biomass and respiration rates of bacteria, nematodes and macrobenthos were estimated in relation to the deposition of the spring phytoplankton bloom at two contrasting sites in the Southern North Sea: one with fine‐grained sediment close to the coastline and another with highly permeable sediments. Sediment community oxygen consumption (SCOC) was also measured. Bacterial biomass was relatively similar at both stations, whereas nematode and macrobenthic biomass were higher in fine‐grained sediment. In fine sediments, bacterial biomass increased quickly after deposition of the phytoplankton bloom, whereas the response of nematodes and macrobenthos was delayed. In coarser sediments, nematodes and macrobenthos also showed a fast response in terms of density and biomass. Respiration in permeable sediments was mainly dominated by bacteria at all periods of the year. Hence, nematode and macrobenthic respiration did not contribute strongly to SCOC. This is in contrast to the patterns observed in finer sediments, where both macrofauna and nematodes were important oxygen consumers as well. Macrobenthos contributed more to total SCOC than did nematodes in winter. However, shortly after the arrival of phytodetritus at the sea floor, nematodes and macrobenthos contributed equally to the total SCOC, indicating that all benthic size classes should be taken into account when investigating marine benthic respiration rates.     

海洋沉积物中现存微生物化学标志物完整极性膜脂研究进展

完整极性膜脂作为活的微生物细胞的化学标志物,能够反映海洋沉积物中现存微生物群落结构和生物量等信息.与生物学方法相比,完整极性膜脂分析技术具有无需培养、快速和普适性等特点.综述了海洋沉积物中细菌和古菌的细胞膜完整极性膜脂的组成特点及其在生物地球化学和微生物生态学等研究中的应用,重点评述了在生物地球化学循环中有特殊作用的微生物,如厌氧氨氧化细菌、甲烷氧化古菌、氨氧化古菌、具有四醚膜脂结构的海洋泉古菌等,或者是一些特殊生态系统,如冷泉、海底深部生物圈等研究中完整极性膜脂应用的进展.还简要介绍了完整极性膜脂的分析方法,并对其应用前景进行了展望.     

Physical, chemical and microbiological characterization of the intertidal sediments of Pereque Beach, Guarujá (SP), Brazil

Physical and chemical characteristics of intertidal sediments and their relationships with bacteria and cyanobacteria were analyzed at four stations at Pereque Beach. Granulometric analysis showed that Pereque beach has sediment that is classified as sand. The lowest value of the sediment C/N rates (6.08), mainly due to a higher concentration of organic nitrogen, was found at the northern part of Pereque Beach, where organic matter of marine source was more prominent. In this area, density (9.6x10(6)cells cm(-3)), biomass (1992.04ngC cm(-3)) and activity of bacteria were higher than at the southern end. In contrast, cyanobacteria density varied from 2.0 to 4.0x10(5)cells cm(-3), with biomass and total chlorophyll a of the sediment being higher at the southern part, where there are water input from Pereque River and higher organic matter of continental origin. The variability in the microbial population is discussed in the light of the sediment granulometry, organic matter quality, fresh water inflow and pollution.     

Bacterial calcification as a possible trigger for francolite precipitation under sulfidic conditions

Francolite (carbonate-fluor-apatite) is known to form in sediments where intense organic-matter decay occurs, but under oxic-to-suboxic conditions, because the alkalinity rise accompanying bacterial sulfate reduction (anoxic conditions) increases francolite solubility, hence preventing its supersaturation and precipitation. However, lagoonal, organic matter-rich, cryptalgal carbonates of Jurassic age located in the French Jura Mountains contain francolite that formed during early diagenesis, under anoxic-sulfidic and highly alkaline conditions. To explain this paradoxical situation, we propose the following “chain of reactions”: the presence of abundant biomass in the sediment would supply the “raw material” to the reactional system, i.e., the initial P budget, released through organic decay. The development of cryptalgal, bacterial mats at the sediment–water interface would have limited exchanges between the water column and the pore space, hampering pore water renewal and favoring the early onset of sulfate-reducing reactions. The onset of sulfate reduction would increase pore water alkalinity, potentially preventing francolite precipitation. In addition, the presence of sulfide ions would induce organic matter sulfurization, resulting in a relative pH rise. Alkalinity and pH rises would trigger the development of conditions leading to carbonate supersaturation, inducing bacterial-structure calcification. The sudden fall in alkalinity induced by early calcification would allow francolite precipitation, despite sulfidic conditions.     

Lab tests on the biodegradation of chemically dispersed oil should consider the rapid dilution that occurs at sea

Most crude oils spread on open water to an average thickness as low as 0.1 mm. The application of dispersants enhances the transport of oil as small droplets into the water column, and when combined with the turbulence of 1 m waves will quickly entrain oil into the top 1 m of the water column, where it rapidly dilutes to concentrations less than 100 ppm. In less than 24 h, the dispersed oil is expected to mix into the top 10 m of the water column and be diluted to concentrations well below 10 ppm, with dilution continuing as time proceeds. Over the multiple weeks that biodegradation takes place, dispersed oil concentrations are expected to be below 1 ppm. Measurements from spills and wave basin studies support these calculations. Published laboratory studies focused on the quantification of contaminant biodegradation rates have used concentrations orders of magnitude greater than this, as it was necessary to ensure the concentrations of hydrocarbons and other chemicals were higher than the detection limits of chemical analysis. However, current analytical methods can quantify individual alkanes and PAHs (and their alkyl homologues) at ppb and ppm levels. To simulate marine biodegradation of dispersed oil at dilute concentrations commonly encountered in the field, laboratory studies should be conducted at similarly low hydrocarbon concentrations.