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41.
Maria de Assunção Franco Jan Vanaverbeke Dick Van Oevelen Karline Soetaert Maria José Costa Magda Vincx Tom Moens 《Marine Ecology》2010,31(2):276-290
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. 相似文献
42.
光合细菌对致病弧菌的抑制作用 总被引:19,自引:3,他引:16
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。 相似文献
43.
从黑潮源区采集上层沉积物,进行DNA提取,以细菌和古菌的16S rDNA通用引物PCR扩增黑潮源区沉积物中细菌和古菌群落的16S rDNA,并构建细菌和古菌的16S rDNA文库,经限制性片段长度多态性分析(Restriction Fragment Length Polymorphism,RFLP),DNA序列测定和系统发育分析,对黑潮源区表层沉积物的细菌和古菌多样性进行了研究。研究结果表明:黑潮源区细菌包括了变形杆菌(Proteobacteria)、酸杆菌(Acidbacterium)、浮霉菌(Planctanycene)、疣微菌(Verrucomicro-bia)和Candidate division OP8和拟杆菌(Bacteroidetes)共6个类群,其中变形杆菌是优势类群。古菌包括了泉古菌(Crenarchaeota)和广古菌(Euryarchaeota),其中泉古菌占优势;泉古菌包括MCG、C3、MBGA和MGI 4个类群,而广古菌包括SAGMEG、MBGE和MEG 3个类群,其中MBGE是优势类群。 相似文献
44.
Brendan P. Burns Roberto Anitori Philip Butterworth Ruth Henneberger Falicia Goh Michelle A. Allen Raquel Ibaez-Peral Peter L. Bergquist Malcolm R. Walter Brett A. Neilan 《Precambrian Research》2009,173(1-4):10
Revealing the geological history of microbial life is very challenging. Microbes rarely are preserved with morphological fidelity, and even when they are, morphology is a poor guide to phylogeny and metabolism. Biological studies of environments considered analogous to those of paleobiological interest on the ancient Earth can inform interpretations and suggest new approaches. This paper reviews recent advances in our understanding of the biological diversity of two environments relevant to Archean paleobiology: those of extreme acidity and temperature (the Mt. Hood and White Island volcanoes), and high salinity (living stromatolites in Shark Bay). The combination of traditional microbial isolation with the use of modern molecular techniques has revealed that the microbial communities in these environments are much more diverse than originally thought. Through the extraction of whole microbial community DNA, enzymatic amplification of evolutionarily conserved genes, and cloning and sequencing of these genes, more specific and informed inferences concerning functional complexity in these extreme environments have now been made. Studies of the modern stromatolites have demonstrated that they have a very diverse range of micoorganisms, and contrary to previous interpretations, cyanobacteria are not the most abundant microbes present. In addition, many of the microorganisms are unique with no known close relatives, and these microorganisms may also possess novel physiologies vital to the integrity and persistence of stromatolites through space and time. Microbes in the volcanoes studied are present ubiquitously and include geochemically significant sulfur- and iron-cycling taxa. The findings from the studies reviewed here suggest that the Archean biota may have been functionally diverse and much more complex than has yet been revealed. The importance of studying modern analogues is stressed in that the biogeochemical processes occurring in these communities leave morphological, mineralogical, lipid and isotopic signals that could be sought in the rock record. 相似文献
45.
46.
Ships carry ballast water for better stability and to control trim. However, the discharge of ballast water near ports is known to transport invasive species from one coastal area to another. The exchange of ballast water on the high seas is supposed to reduce such invasions of exotic species. In this study, we used denaturing gradient gel electrophoresis (DGGE) to analyze the composition of the bacterial community in ballast water before and after such a mid-ocean exchange, and we also measured total bacterial counts. Our findings confirmed that the ballast water was replaced by the mid-ocean exchange, as indicated by the marked change in the composition of the bacterial community. There was also a significant decrease in bacterial abundance after the mid-ocean exchange. Finally, our findings support the incubation hypothesis, because the composition of the bacterial communities changed over time within the same ballast water. 相似文献
47.
南沙海区沉积物中细菌和古细菌16S rDNA多样性的研究 总被引:10,自引:1,他引:10
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。 相似文献
48.
The objectives of this study were to determine the distribution and abundance of Zostera marina (eelgrass) in relation to the distribution of the mat forming bacteria Beggiatoa spp., and the levels of sulfide and organic material (wood waste) in the sediment. Underwater videography and intertidal surveys were used to map the distribution and abundance of Z. marina beds and Beggiatoa in the nearshore area of Commencement Bay, WA (USA), a location that has a long history of sawmill activity. Zostera marina occurred from the intertidal to ?6 m mean lower low water (MLLW) on sandy substrates in areas with low levels of sulfide (<50 μm ) and organic material (<5 % total volatile solids). Areas with high sulfide levels (>200 μm ) occurred where there were significant amounts of organic material in the sediments, which was found to be wood waste that had been discarded from sawmills. Zostera marina was absent from the intertidal and occurred at lower densities in areas with high sulfide levels. In contrast, mats of Beggiatoa were only found in areas where the sulfide levels were >1000 μm and there were significant deposits of wood. Thus, the negative correlation between the distribution and abundance of Z. marina and Beggiatoa suggests that the presence of Beggiatoa mats could be used as a biological indicator of inhibiting levels of hydrogen sulfide in the marine environment. 相似文献
49.
On the basis of mass balance calculations performed for nitrogen (N) uptake experiments in the Southern California Bight (SCB), it has been suggested that a significant portion of dissolved inorganic N (DIN) uptake results in the production of dissolved organic N (DON). To investigate this process, the fate of ammonium (NH4+) and nitrate (NO3−) uptake was quantified within the euphotic zone at three coastal stations in the SCB using 15N tracer techniques. Several trends in the fate of DIN and the production of DON were observed. First, production of particulate N (PN), from both NH4+ and NO3−, was quantitatively more important in near surface waters, while DON release dominated within the nitracline. Second, the percentage of gross N uptake released as DON was generally higher when NO3−, rather than NH4+, was the substrate. Third, the percentage of N released as DON was higher at night, relative to the day. Fourth, rates of DON release were significantly correlated to NH4+ regeneration, suggesting that similar mechanisms are responsible for both processes—presumably grazing. The results of this study indicate that the DON pool is a sink for DIN uptake on the time scale of hours. One implication of this finding is that new production estimates based on 15NO3− uptake rates will likely underestimate particle flux out of the surface layer because the rate of NO3− uptake is underestimated due to loss of DO15N during the incubation. On time scales of months to years, however, the N that is taken up as NO3− and released as DON will likely contribute to export flux via incorporation of the dissolved phase during seasonal mixing into sinking particles or transport. The export of DON on these time scales argues for the use of gross uptake rates to calculate f-ratios. 相似文献
50.