水温对南美白对虾肠道菌群影响的研究   总被引：8，自引：0，他引：8  

尹军霞  沈文英  郦萍 《海洋科学》2004,28(5):33-36

在不同温度下 ,对南美白对虾 (Penaeusvannamei)肠道乳酸杆菌(Lactobacillussp.)、双歧杆菌(Bifidobactsp.)、大肠杆菌(Escherichiacoli)、金黄色葡萄球菌(Staphylococcusaureus)、副溶血性弧菌(Vibrioparahaemolyticus)、产气荚膜梭菌产气荚膜梭菌(Clostridiumperfringens)、厌氧菌总数和好氧菌总数进行了定性定量分析。结果表明 ,大肠杆菌、金黄色葡萄球菌、副溶血性弧菌、产气荚膜梭菌为过路菌群 ;乳酸杆菌、双歧杆菌为常住菌群。厌氧菌总数、双歧杆菌随水温升高显著增加 (Ftest,P<0.01) ;好氧菌总数、乳酸杆菌随水温升高变化不显著(Ftest,P>0.05)。肠道中厌氧菌总数比好氧菌多(ttest,P<0.05) ,且随着水温升高 ,厌氧菌的优势越明显。  相似文献   

Seasonal distribution of bacteria in salt marsh sediments in North Carolina     

Parke A. Rublee 《Estuarine, Coastal and Shelf Science》1982,15(1):67-74

The number and size of bacteria at four depths (0–1, 5–6, 10–11 and 20–21 cm) in a North Carolina salt marsh were minotored by direct counts for 13 months. The number of bacteria reached a maximum of about 1·4 × 10¹⁰ cells cm^?3 at the sediment surface in October, corresponding to the period of Spartina alterniflora die-back. Cell numbers were lowest and most consistent throughout the year at the 20 cm depth of sediment. Cell volumes averaged 0·2 μm³ at the marsh surface and decreased with depth. Mean standing crop of bacteria to a depth of 20 cm of sediment was about 14 g bacterial carbon m^?2. In surface sediments bacteria contribute up to 15% and algae up to 10% of total living microbial biomass as estimated by adenosine triphosphate (ATP). Bacteria were the major biomass component at sediment depths of 5, 10 and 20 cm. At all depths the microbial community contributes < 4% total organic carbon and < 8% of total nitrogen.  相似文献   

近江牡蛎肠道细菌及其产酶能力     

祝玲  杨吉霞  蔡俊鹏  余德民 《广东海洋大学学报》2005,25(1):10-13

从近江牡蛎肠道中分离出21株菌,其中, 9株为革兰阳性菌, 12株革兰阴性菌。为寻找能分泌多种酶的有益微生物,研究了它们蛋白酶、脂肪酶、淀粉酶、纤维素酶的产酶能力。结果表明,有61 .9%的菌株能分泌蛋白酶或淀粉酶(各有13株菌);有52. 4%的菌株能分泌脂肪酶(11株菌);有33. 3%的菌株能产纤维素酶(7株菌)。在这21株菌中,产4种酶的有5株菌,产3种酶的3株菌,产两种酶的5株菌,产1种酶的3株菌,不产酶的仅有5株菌。不产酶的菌株仅占细菌总数的23. 8%,而各种产酶菌则高达76. 2%,由此表明细菌在近江牡蛎对食饵消化过程的重要性。  相似文献   

Degradation Kinetics of Petroleum Contaminants in Soft-Water Systems     

ZHENGXilai WANGBingchen LIYuying XIAWenxiang 《《地质学报》英文版》2004,78(3):825-828

On the basis of site investigation and sample collection of petroleum contaminants in the soil-water-crop system in the Shenyang-Fushun sewage irrigation area, the physical-chemical-biological compositions of the unsaturated zone is analyzed systematically in this paper. At the same time, the degradation kinetics of residual and aqueous oils is determined through biodegradation tests. The studies show that dominant microorganisms have been formed in the soils after long-term sewage irrigation. The microorganisms mainly include bacteria, and a few of fungus and actinomycetes.After a 110-days‘ biodegradation test, the degradation rate of residual oil is 9.74%--10.63%, while the degradation rate of aqueous oil reaches 62.43 %. This indicates that the degradation rate of low-carbon aqueous oil is higher than that of highcarbon residual oil. In addition, although microbial degradation of petroleum contaminants in soils is suitable to the firstorder kinetics equation, the half-lives of aqueous oil, No. 20 heavy diesel and residual oil in the surface soils (L2-1, S1-1 and X1-1) are 1732 h, 3465 h and 17325 h, respectively.  相似文献   

Ancient wet aeolian environments on Earth: clues to presence of fossil/live microorganisms on Mars     

William C Mahaney  Michael W Milner  David Malloch  Victor R Baker  Trent M Hare 《Icarus》2004,171(1):39-53

Ancient wet aeolian (wet-sabkha) environments on Earth, represented in the Entrada and Navajo sandstones of Utah, contain pipe structures considered to be the product of gas/water release under pressure. The sediments originally had considerable porosity allowing the ingress of living plant structures, microorganisms, clay minerals, and fine-grained primary minerals of silt and sand size from the surface downward in the sedimentary column. Host rock material is of a similar size and porosity and presumably the downward migration of fine-grained material would have been possible prior to lithogenesis and final cementation. Recent field emission scanning electron microscopy (FESEM) and EDS (energy-dispersive spectrometry) examination of sands from fluidized pipes in the Early Jurassic Navajo Sandstone reveal the presence of fossil forms resembling fungal filaments, some bearing hyphopodium-like structures similar to those produced by modern tropical leaf parasites. The tropical origin of the fungi is consistent with the paleogeography of the sandstone, which was deposited in a tropical arid environment. These fossil fungi are silicized, with minor amounts of CaCO₃ and Fe, and in some cases a Si/Al ratio similar to smectite. They exist as pseudomorphs, totally depleted in nitrogen, adhering to the surfaces of fine-grained sands, principally quartz and orthoclase. Similar wet aeolian paleoenvironments are suspected for Mars, especially following catastrophic sediment-charged floods of enormous magnitudes that are believed to have contributed to rapid formation of large water bodies in the northern plains, ranging from lakes to oceans. These events are suspected to have contributed to a high frequency of constructional landforms (also known as pseudocraters) related to trapped volatiles and water-enriched sediment underneath a thick blanket of materials that were subsequently released to the martian surface, forming piping structures at the near surface and constructional landforms at the surface. This constructional process on Mars may help unravel the complex history of some of the piping structures observed on Earth; on Earth, evidence for the constructional landforms has been all but erased and the near-surface piping structures exposed through millions of years of differential erosion and topographic inversion now occur as high-standing promontories. If the features on both Earth and Mars formed by similar processes, especially involving water and other volatiles, and since the piping structures of Earth provided suitable environments for life to thrive in, the martian features in the northern plains should be considered as prime targets for physico/mineral/chemical/microbiological analyses once the astrobiological exploration of the red planet begins in earnest.  相似文献   

Desert Potholes: Ephemeral Aquatic Microsystems   总被引：1，自引：0，他引：1  

Marjorie?A.?ChanEmail author  Katrina?Moser  Jim?M.?Davis  Gordon?Southam  Kebbi?Hughes  Tim?Graham 《Aquatic Geochemistry》2005,11(3):279-302

An enigma of the Colorado Plateau high desert is the “pothole”, which ranges from shallow ephemeral puddles to deeply carved pools. The existence of prokaryotic to eukaryotic organisms within these pools is largely controlled by the presence of collected rainwater. Multivariate statistical analysis of physical and chemical limnologic data variables measured from potholes indicates spatial and temporal variations, particularly in water depth, manganese, iron, nitrate and sulfate concentrations and salinity. Variation in water depth and salinity are likely related to the amount of time since the last precipitation, whereas the other variables may be related to redox potential. The spatial and temporal variations in water chemistry affect the distribution of organisms, which must adapt to daily and seasonal extremes of fluctuating temperature (0–60 °C), pH changes of as much as 5 units over 12 days, and desiccation. For example, many species become dormant when potholes dry, in order to endure intense heat, UV radiation, desiccation and freezing, only to flourish again upon rehydration. But the pothole organisms also have a profound impact on the potholes. Through photosynthesis and respiration, pothole organisms affect redox potential, and indirectly alter the water chemistry. Laboratory examination of dried biofilm from the potholes revealed that within 2 weeks of hydration, the surface of the desiccated, black biofilm became green from cyanobacterial growth, which supported significant growth in heterotrophic bacterial populations. This complex biofilm is persumably responsible for dissolving the cement between the sandstone grains, allowing the potholes to enlarge, and for sealing the potholes, enabling them to retain water longer than the surrounding sandstone. Despite the remarkable ability of life in potholes to persist, desert potholes may be extremely sensitive to anthropogenic effects. The unique limnology and ecology of Utah potholes holds great scientific value for understanding water–rock–biological interactions with possible applications to life on other planetary bodies.  相似文献   

青藏高原多年冻土微生物的分离分析及其意义   总被引：6，自引：9，他引：6  

刘光  胡昌勤  张靖溥  沈永平 《冰川冻土》2001,23(4):419-422

对取自昆仑山垭口2m钻孔的21个样品中的微生物进行了分离鉴定，并对其生长速度和耐药性进行了初步分析，结果表明：青藏高原多年冻土中有微生物存在，其种类表现为临床少见，生长速度缓慢，冻土微生物的生长表现为嗜冷性，在35℃时生长停止，反映其有特殊的生理活动机制，分离细菌的耐药性分析，发现冻土中有较大比例的耐药细菌，反映了高原微生物的特殊性。  相似文献   

气象要素对肠道传染病的影响及预报   总被引：10，自引：0，他引：10  

张晓云  刘彬贤  刘艳  张之伦  谢咏 《气象》2002,28(5):53-55

根据1980－1988年天津市肠道传染病发病资料与气象台同步观测资料，分析发病资料和气象资料的变化规律，并与前期的气象要素进行相关分析，揭示出由于气象条件的变化导致肠道传染病发病的周期性规律。采用逐步回归方法建立天津市肠道传染病发病率月预报方程，取得了较好的预报效果。  相似文献   

Airborne microorganisms: Their occurrence,distribution and dependence on environmental factors — Especially on organic compounds of air-pollution     

Priv.-Doz. Dr. med. H. Rüden  Prof. Dr. med. E. Thofern  Dr. med. P. Fischer  Dr. Ing. U. Mihm 《Pure and Applied Geophysics》1978,116(2-3):335-350

For a period of approximately six months the concentrations of airborne microorganisms were determined by the uptake of their day-characteristic at local places differing by the extent of air pollution. By simultaneously recording the meteorological parameters as temperature, relative humidity, direction and velocity of wind and intensity of solar radiation, it was intended to find out the relationship between these factors and the viability of airborne microorganisms. The present data show an oscillation of the concentration counts over a wide range and seem not yet to depend on the local situation of air pollution.In a further series of experiments the atmospheric aerosol <10 m was collected on air-filters. The decreased substances were extracted from the filter material by aqueous and organic solutants and tested for their antimicrobial activities. In this context the seasonal dependence of the microbicidal activity of organic compounds of aerosol is discussed.  相似文献   

An application of Iatroscan thin-layer chromatography with flame ionization detection—lipid classes of microorganisms as biomarkers in the marine environment     

M. Goutx  C. Gerin  J.C. Bertrand 《Organic Geochemistry》1990,16(4-6)

Iatroscan TLC-FID combines the separatory capabilities of thin-layer chromatography (TLC) (on silica coated chromarods) with the possibility of quantitation by flame ionization detection (FID). It can be used to separate lipid extracts into classes of compounds ranging from neutral to polar products. The rapidity with which this system provides lipid class profiles from small samples makes it particularly useful in oceanographic studies where routine analyses of large numbers of samples are required. Lipid classes were analysed in 4 marine bacterial strains grown on various substrates and 10 microalgae isolated from the marine environment and grown in batch cultures. Data on lipid composition of these microorganisms were obtained and compared to literature data. Results show that ratios between classes of compounds within the different groups of microorganisms were characteristic enough to constitute a good print of bacterial or phytoplankton sources in organic matter in sea water. In a preliminary study, phospholipid classes from a bacterial strain and a microalga were separated. Results show that the determination of ratios between phospholipid classes in organic matter could represent an improvement in the utilization of lipid classes as biomarkers.  相似文献