Bacterial Input Research Articles

Organic geochemistry of marine sediments of the Subantarctic Indian Ocean sector: Lipid classes—sources and fate

Nine sections of core KTB16 (47°59′98 S, 55°59′74 E, 4240 m) taken from the Indian Ocean sector of the Antarctic Polar Front Zone were analyzed for their lipid class and total chlorin contents using thin-layer chromatography-flame ionisation detection (TLC/FID). The following series were included: hydrocarbons, chlorins and chlorin esters, alcohols, sterols, triacylglycerols, free fatty acids and phospholipids. For these major classes, the distribution of their individual components was determined to evaluate the source and fate of each lipid class. Relationships between the lipid composition of overlying particles and of buried material were investigated. The sediment-water interface was found to be of primary importance in the biogeochemical transformations occurring in organic matter, such as loss of the major part of the lipids, and formation of a notable unresolved complex mixture (UCM), of biological origin. Some classes such as chlorin esters appeared to convey their lipid contents from the upper layers without major alteration. In contrast, several other classes, such as storage lipids, appeared to be degraded during sedimentation, indicating extensive recycling of labile lipids in the water column. The burial efficiency and bacterial inputs downcore were highly variable depending on the class considered. Several novel compounds are reported. They consist of alkyl chlorin esters and include a wide variety of saturated and unsaturated long-chain alcohols. Owing to the lack of lipid data in the study area, these results provide an insight into the various biological and chemical processes occurring in open-sea Antarctic sedimentary environments.

Bacterial abundance and diversity in the Barbados Trench determined by phospholipid analysis

The Barbados trench is characterized by large fields of volcanoes and mounds located over a distance of 30 km above the northern slope of a basement ridge corresponding to an inactive transform fault. Sediments from various locations were collected and analyzed for their lipid contents. Bacterial input to the overall biomass was estimated through the analysis of phospholipid ester-linked fatty acid (PLFA) profiles and glycerol ether lipids. Results indicated a eubacterial biomass estimated to be 109cells (g dry wt)−1. Individual fatty acid profiles revealed the presence of sulfur-oxidizing bacteria common to many deep-sea sites but also a large contribution of type I and type II methanotrophs to the eubacterial biomass. The presence of methanotrophs was further supported by the analysis of specific biomarkers of these microorganisms as well as some unusual trans fatty acid isomers. Anaerobic bacteria and presumbly sulfate reducing bacteria were also present, as well as archaebacteria and primarily methanogens, as indicated by glycerol ether lipid analysis.

Bacterial abundance and diversity in the Barbados Trench determined by phospholipid analysis

The Barbados trench is characterized by large fields of volcanoes and mounds located over a distance of 30 km above the northern slope of a basement ridge corresponding to an inactive transform fault. Sediments from various locations were collected and analyzed for their lipid contents. Bacterial input to the overall biomass was estimated through the analysis of phospholipid ester-linked fatty acid (PLFA) profiles and glycerol ether lipids. Results indicated a eubacterial biomass estimated to be 10 9cells (g dry wt) −1. Individual fatty acid profiles revealed the presence of sulfur-oxidizing bacteria common to many deep-sea sites but also a large contribution of type I and type II methanotrophs to the eubacterial biomass. The presence of methanotrophs was further supported by the analysis of specific biomarkers of these microorganisms as well as some unusual trans fatty acid isomers. Anaerobic bacteria and presumbly sulfate reducing bacteria were also present, as well as archaebacteria and primarily methanogens, as indicated by glycerol ether lipid analysis.

Using a new inbred fish model and cultured fish tissue cells to study Aeromonas hydrophilaand Yersinia ruckeripathogenesis

An inbred strain of the southern platyfish, Xiphophorus maculatus, was used as a host for Aeromonas hydrophilaand Yersinia ruckeriinfections. The infections were initiated by holding the platyfish in inoculation baths containing dilutions of virulent A. hydrophilaor Y. ruckeristrains. Inoculating the platyfish in this manner resulted in a dose-dependent mortality over a range of bacterial input from 10 5to 10 8 A. hydrophilaand 10 6to 10 8 Y. ruckeri/ml. Clinical manifestations of A. hydrophilainfections were noted in infected platyfish that eventually died, but not in platyfish that survived. In this model, the Y. ruckeriinfected fish died before obvious signs of infection were detected. The A. hydrophilastrain used to establish the infections was recovered from the kidney and intestine of infected fish that died, but not from survivors receiving the same inoculation dose. Both infective bacteria were tested for the ability to invade a number of different fish and human cultured cells. A. hydrophilastrain TF7 did not invade any of the cells tested, whereas the Y. ruckeristrain invaded fish derived cultured cells, but not human derived Hep-2 cells.

Comparison of solutes, nutrients, and bacteria inputs from two types of groundwater to the Rh�ne river during an artificial drought

Solute, nutrient and bacterial inputs to the River Rhone from the interstitial habitat of a gravel bar and the floodplain aquifer were investigated during an artificial drought. Eight springs were investigated: four groundwater-fed springs in the floodplain, located at the bottom of the bank; and four interstitial-fed springs located at the downstream end of a gravel bar. During this period, the inflows of groundwater to the river represented an average input of 0.77 mg l−1 of nitrogen (of which 93.3% were nitrates), 0.0187 mg l−1 of total phosphorus (of which 42.2% was orthophosphate), 3.56 mg l−1 of silica, 2.315 ± 0.703 mg l−1 of dissolved organic carbon (DOC, of which 47% was biodegradable) and 7.3 × 104 ± 3.7 × 104 bacteria per ml (of which 8.8% were active). Silica, DOC, biodegradable DOC, and bacteria concentrations displayed temporal variations during the study, which seem to be linked to the biological activity of the groundwater biofilm. There was a strong heterogeneity between the two types of groundwater that flow to the river: concentrations of calcium and alkalinity were higher in bank springs than in gravel bars springs. In these latters, sulfate, sodium, nitrogen, phosphorus were significantly higher.

Geochemical Features of Oils from Western and Southern Gulf of Mexico: Reconstruction of the Depositional Environment of Their Source Rocks: ABSTRACT

Three main source rock depositional environments can be interpreted from the western and southern Gulf of Mexico oils: marine deltaic, marine carbonate and marine carbonate evaporitic. Marine deltaic oils are geographically limited to the Burgos and Macuspana basins. Their molecular features suggest a source from reworked, bacterially degraded terrestrial higher plants deposited in siliciclastic dysaerobic depositional environments. They can be recognized by their {delta}{sup 13}C values (between 23.6 to -21.7 {per_thousand}), low sulphur content (0.06 to 0.12 wt % S), high pristane/phytane ratios (1.95 to 3.43), high concentrations of oleanane, and very low sterane/hopane mbbs (<0.05). Marine carbonate oils have a widespread distribution throughout the western and southern Gulf of Mexico. They are present from Tampico Basin to Campeche Sound. Isotopic values of these oils range from -24 to -28.1 {per_thousand}. They are characterized by medium to high sulphur content, pristane/phytane <1, abundant extended hopanes C{sub 35} hopanes greater than or in similar abundance to their C{sub 34} counterparts, and presence of hexahydrobenzohopanes. Subtle internal differences in biomarker composition of this oil set can be interpreted in terms of salinity, clay content and oxygen depletion variations. Marine carbonate evaporitic oils are present in the Veracruz Basin and the Chiapas-Tabasco area.more » The oils are recognized by their heavy {delta}{sup 13}C values (between -23 to -24 {per_thousand}), very low sterane/hopane ratios, high C24-tetracyclics/C26-tricyclics terpanes ratios, and C{sub 33} hopanes greater than their C{sub 34} counterparts. In this oil set the organic matter is dominated by a strongly prevailing bacterial input. The diversity of oil families from the western and southern Gulf of Mexico explains the enormous petroleum potential of this region.« less

Delivery of microbial indicator organisms to coastal waters from catchment sources

The introduction of ultraviolet disinfection of sewage effluent in Jersey has served to focus attention on other sources of faecal pollution responsible for subsequent compliance failures in coastal water quality in St Aubin's Bay. Studies of microbial concentrations (total coliforms, faecal coliforms and faecal streptococci) in streams draining to the bay showed concentrations to be elevated by an order of magnitude or more following rainfall. Detailed monitoring of indicator organisms during hydrograph events showed rapid increases in concentration with flow associated with the rising limb of the hydrograph and transport of suspended solids. Microbial budget estimates suggested that between 42 and 97% of microbial delivery was associated with high flows, which account for just 20% of the total discharge. Budgets also revealed the relative importance of different catchment inputs, revealing the low bacterial input associated with UV treated effluent which provided 48% of the total volume discharged to the bay. Implications for water quality standards are discussed with reference to catchment management planning.

Delivery of microbial indicator organisms to coastal waters from catchment sources

The introduction of ultraviolet disinfection of sewage effluent in Jersey has served to focus attention on other sources of faecal pollution responsible for subsequent compliance failures in coastal water quality in St Aubin's Bay. Studies of microbial concentrations (total coliforms, faecal coliforms and faecal streptococci) in streams draining to the bay showed concentrations to be elevated by an order of magnitude or more following rainfall. Detailed monitoring of indicator organisms during hydrograph events showed rapid increases in concentration with flow associated with the rising limb of the hydrograph and transport of suspended solids. Microbial budget estimates suggested that between 42 and 97% of microbial delivery was associated with high flows, which account for just 20% of the total discharge. Budgets also revealed the relative importance of different catchment inputs, revealing the low bacterial input associated with LTV treated effluent which provided 48% of the total volume discharged to the bay. Implications for water quality standards are discussed with reference to catchment management planning.

Grain size effect on bound lipids in sediments off northeastern Taiwan

Two box-core sediments off the northeastern Taiwan coast have been collected and examined for the relationship between bound lipids and grain size in the mud fraction (<63 μm). No grain size effect was found for the concentrations of σ n-alkanes, σ n-fatty acids and σ n-alcohols. The ratios of branched-chain to normal fatty acids increased progressively with decreasing particle size and correlated highly with BOC (bound organic carbon), suggesting an increasing bacterial input. Moreover, we observed an increase in the ratios of monounsaturated to saturated fatty acids with decreasing grain size, pointing to an increasing microbial contribution. Particularly interesting is phytol, which demonstrated a remarkable grain size effect; the phytol to BOC ratio increased sharply with decreasing particle size. Major sterols normalized to BOC increased progressively with a decrease in grain size and correlated highly with BOC. The results indicate that a plankton contribution to phytol and sterols increased as particle size decreased. The grain size effect is stronger for phytol than for sterols and branched-chain fatty acids in the sediments.

Fatty acids as markers of food sources in a shallow-water hydrothermal ecosystem (Kraternaya Bight, Yankich Island, Kurile Islands)

The contribution of different food sources in the food web of a shallow-water hydrothermal ecosystem was estimated using fatty acids as markers. The markers were selected based on the results of analyzing the fatty acid composition of potential food sources in Kraternaya Right, Yankich Island, Kurile Islands. Most animals had markers characteristic of diatoms: the 16:0/16:1m? ratio close to 1 and a high 20:503 content. We assume that the bivalves Macoma calcared and Macoma lukini, polychaetes Amphitrite cirrata and Pectinaria hyperborea, and holothurians Eupentacta pseudoquinquesemita and Psolus sp. feed mainly on diatoms. Fatty a c ~ d s pecific to bacteria branched, odd and 18:lw7 -were found in considerable amounts in the bivalve Ax~nopsida orbiculata, as well as in E pseudoquinquesernita, Psolus sp and P. hyperborea; hence we concluded that there was a substantial bacterial input into the food of these species. A high concentrat~on of C,, and PUFAs (polyunsaturated fatty acids), suggested to be an indicator of brown algae, was detected merely in the gastropod Littorina kurila. Although bactena are more important as a food source in Kraternaya Bight than In typical coastal ecosystems, the major food source for animals here is photosynthetic organisms, rather than chernosynthetic symbionts as is the case with deep-sea hydrothermal vents.

Urban Wastewater Discharge and Bacteriological Quality of Receiving Coastal Waters: Processes and Modelling

The aim of this paper is to present some results of bacterial studies which were developed by IFREMER in coastal discharge areas of urban wastewaters; they are focused on the determination of bacterial inputs by wastewater treatment plants, the role of environmental factors on the enteric bacteria survival in the coastal zone, and the modelling of bacteria transport and disappearance in order to provide useful management information for minimizing faecal pollution in the coastal zone.

Input of fecal coliform bacteria to an upland stream channel in the Yorkshire Dales

The input of fecal coliform bacteria to the River Skell stream from a small, approximately 0.5 ha, instrumented research site on Pateley Moor in the Yorkshire Dales was investigated. Bacterial concentrations were determined for a total of 433 water samples collected between October and December 1984 from 31 stream bank sites representing three types of near‐surface water flow: matrix through flow, nonmatrix through flow, and overland flow. Bacterial concentrations in matrix through flow were found to be very low, but much higher input rates were found in both nonmatrix through flow and overland flow. Overland flow sites were the most important group for the input of bacteria to the channel, both between and during storm events. The rate of fecal coliform input was found to increase during storm events, and there was a strong, positive correlation between bacterial input rate and stream stage height.

A lamina-scale geochemical and sedimentological study of sediments from the Peru Margin (Site 680, ODP Leg 112)

Abstract Individual laminae (mm-cm) were isolated from late Pliocene-Holocene sediments cored at Site 680 during ODP Leg 112 (Peru upwelling region). At all depths, individual laminae alternate between (1) pale, high porosity, clay-poor, diatom ‘framework’ oozes containing a high proportion of complete, well preserved diatom frustules and (2) dark, low porosity diatomaceous muds containing abundant diatom debris and foraminifer tests. In some instances, detrital-rich laminae with low amounts of diatom debris were also observed. Hydrogen-rich organic matter is finely disseminated throughout the sediments, perhaps occurring as coatings on detrital and biogenic grains. Both carbon isotopic and pyrolysis-GCMS analyses suggest that the organic matter is derived mainly from a marine algal and/or bacterial input. Py-GCMS further shows that, even in the sediments from 4.91 mbsf, the organic matter is significantly altered from the composition of living organisms. Only in two organic-lean Pliocene samples was there any sign of a significant input of terrestrial organic matter. Relative to laminae deposited during the Pleistocene-Holocene, late Pliocene laminae are depleted in TOC. This may reflect variations in primary productivity. TOC contents also vary between adjacent diatomaceous mud laminae in Pleistocene-Holocene sediments. In these laminae, TOC is inversely proportional to diatom abundance (which is believed to be related to productivity) but correlates positively with detrital content. Variations in the TOC content of closely spaced laminae is apparently not controlled by variations in productivity or preservation, but probably by variations in the TOC content of particulate matter reaching the sediment-water interface. Some parameters (organic S/C; δ 34 S) vary on a lamina scale — no larger scale trends are apparent. These variations are presumably the result of short-term, local changes in diagenetic conditions and are hard to quantify. In these H 2 S-rich sediments, differential uptake of sulphur into organic matter may be caused by variations in the availability of specific, reactive inorganic sulphur species, perhaps polysulphides. This study shows that conventional geochemical analysis of bulk, or of widely spaced samples can hide significant variations in sediment composition and inferred palaeoceanographical conditions. Although bulk samples may be used to determine the gross characteristics of a sedimentary sequence, fine-scale sampling is needed to define the processes which determined those characteristics.

The decoupling of hydrocarbons and fatty acids in the dissolved and particulate water phases of a deltaic environment

Hydrocarbons and fatty acids have been analysed in the dissolved and particulate phases of a series of 46 water samples collected over a period of 16 months in different environments of the Ebro Delta (bays, channels and river-bed). Several qualitative and quantitative differences have regularly been observed between the particulate and the dissolved fractions, such as higher concentrations and spatial variability of lipids in the particulates, which are also enriched in unsaturated components. Furthermore, an apparent source-related decoupling between both phases has been detected by a cross-correlation study of the multivariate dataset resulting from the distributions of these components. In the dissolved fraction they have been classified into three groups. The largest, consisting mostly of hydrocarbons, reflects the anthropogenic (urban- and petroleumrelated) inputs. The second is composed of some C 15-C 20 fatty acids and represents the biogenic autochthonous inputs, especially those of algal origin. A third group is formed by the C 21-C 30 n-alkanoic acids and corresponds to the terrigenous distributions. However, the biogenic sources are better characterized in the particulate phase where groups of components reflecting algal, bacterial and terrestrial inputs have been observed.

The microbial input in carbonate-anhydrite facies of a sabkha palaeoenvironment from Guatemala: A molecular approach

Nine representative rock samplesincluding four anhydrites, an oil-stained dolomite and a laminated mudstone (source rock) from a sabkha-type palaeoenvironment (La Felicidad 1 well, Guatemala) have been compared in order to tentatively characterize each facies by a geochemical signature. Each sample has been studied by using basic parameters (TOC, Rock-Eval pyrolysis yields) and analyses of alkanes and aromatics by computerized GC-MS. The following families of compounds have been reviewed: n-alkanes, branched and cyclic alkanes, n-alkylbenzenes, benzohopanes, monoaromatic steroids, D-ring aromatic 8,14-secohopanoids, alkylnaphthalenes, alkylphenanthrenes, alkyldibenzothiophenes and triaromatic steroids. Despite close geochemical relationships of all the sample, a more in-depth investigation taking into account molecular patterns and semi-quantitative data reveals significant differences among the samples. Anhydrites may be differentiated from carbonates which illustrates the efficiency of organic geochemistry in environmental palaeoreconstruction even in organiccarbon-lean sediments (TOC = 0.04–0.08% in anhydrites). In these anoxic, marginally mature sediments the strong predominance of triterpanes over steranes (TT to ST > 20) associated with other molecular features leads to the conclusion that the main contribution to the organic matter of all facies is by bacteria. Several prominent components including novel families (iso-C 23 and iso-C 27 alkanes, tetracyclic terpanes, D-ring aromatic 8–14-secohopanoids, 1-phenylpentadecane, undecylnaphathalene and their mono- and dimethylated counterparts) have been interpreted as derived from halophilic bacteria. These conclusions may be extended to all crude oils from the same area which may be considered as true bacterially-derived petroleums. The La Felicidad 1 well data are discussed with reference to other palaeosabkha-type sequences from the SW Aquitaine Basin (France) in which the bacterial input is less important. However, in these sabkha sequences 1-phenylpentadecane, undecylnaphthalene and related structures have also been identified.

Organic geochemical studies of a Messinian evaporitic basin, northern Apennines (Italy)—II Isoprenoid and n-alkyl thiophenes and thiolanes

Series of n-alkyl and isoprenoid thiophenes and thiolanes, most of which have not been previously reported, have been identified in an extract from a Messinian (Upper Miocene) marl layer deposited under hypersaline, euxinic conditions. The identifications were based on mass spectra and Chromatographic data of synthesized reference compounds and on comparison of mass spectra, relative retention times and response on the FPD. Their specific structures and their distribution patterns show similarities with those of the alkanes. Inorganic sulphur is therefore considered to be incorporated into specific lipid moieties from (archae)bacterial and/or algal input during diagenesis. A biosynthetic origin of these compounds is also possible, however. The organic sulphur compounds encountered are thought to be indicators of a hypersaline depositional environment.

Comparison of the lipid composition of sediments from three sites in the Venezuela Basin

Solvent extractable and bound lipids from pelagic (site 1), turbidite (site 2) and hemipelagic (site 3) sediments of the Venezuela Basin have been analysed to indicate input sources of sedimentary lipids. Acids consist mainly of normal, branched, monoenoic and cyclopropyl components less than 24 carbons long with concentration and distribution indicating bacterial inputs of a similar level to each site. Long-chain acids, alcohols and 24-ethylcholest-5-en-3β-ol represent an input of higher plant-derived organics, which maximizes at sites 2 and 3. The source of this material is likely to be the Orinoco and Amazon river systems. Algal input is suggested by the distribution of sterols comprising diatoms and coccolithophores (24-methyl sterols), and dinoflagellates (dinosterol and other 4-methyl sterols). Algal and short-chain higher plant acids are absent, probably due to degradation of cellular material in the water column and microbial utilization of lipids in the surface sediment.

Regional Organic Geochemistry of Offshore Louisiana: ABSTRACT

Geochemical analyses of well cuttings from offshore Louisiana reveal trends inorganic matter characteristics that mimic thermal alteration effects, but are in fact related to depositional environments. Sediments deposited on the continental slope contain organic matter that is considerably higher in hydrogen content than organic matter from adjacent environments. These chemical variations are reflected in headspace composition of canned cuttings. Slope sediments, at or near the top of the oil window over a widespread area, are commonly encountered near the base of the penetrated section, leaving the greater part of the principal zone of oil generation unsampled. Active petroleum generation must occur deeper than 8,000-15,000 ft, depending on local geothermal gradient. Mod l calculations of thermal maturity, used in conjunction with burial history analysis, are consistent with our empirical observations of the maturation of organic matter based on vitrinite reflectance and geothermal gradient. In the absence of direct evidence from the source beds of Gulf of Mexico oils, detailed biomarker analysis can provide information on the nature and thermal history of the organic matter from which the oils were generated. Thermal maturity of the oils increases from west to east, indicating that source beds of eastern oils are older than those of western oils. Oils produced from the eastern offshore region were probably generated from early to middle Miocene sediments. The depocenter was located to the northwest, and deposition of oil-generating sediments enriched in marine organic matter occurred in deep water. Oils produced from the western offshore region were probably generated from Pliocene sediments. The depocenter was located close to where the oils are found today; hence, the ils are enriched in components derived from land plants deposited in oxygenated sediments. Oils produced from two locations close to the present-day shelf edge are significantly different from the other offshore oils. These were probably generated from middle to late Miocene sediments deposited in anoxic basins with high bacterial input. End_of_Article - Last_Page 1431------------

Extractable and bound neutral lipids in some lacustrine sediments

The extractable and bound neutral lipids from sediments of two lacustrine environments, viz. coastal lagoons (Ebro Delta) and shallow hypersaline ponds (Los Monegros) have been examined. The coastal lagoons were generally eutrophic and their autochthonous plankton changed seasonally from freshwater (e.g. Phormidium and Nitzschia sp.) to marine ( Dunaliella) species. The sediments at Los Monegros consist of cyanobacterial algal mats ( Microcoleus) with an underlying black sapropel layer. Alkanes, alkenes, alkanols, sterols and carbonyl compounds were analyzed by GC-MS and exhibited significant differences between the free and bound fractions. The data obtained support earlier suggestions that allochthonous lipids are not incorporated into the bound fraction whereas bacterial input is largely reflected within this fraction. In addition to biological markers indicative of allochthonous (terrestrial) and authochthonous (algal and bacterial) inputs other compounds, including diterpenes (sclarene isomers) multibranched C 25 alkenes (C 25 : 2 and C 25 : 3) and hydrosqualenes (C 30 : 2-C 30 : 6) have been identified in lacustrine sediments for the first time. A series of components of diagenetic origin are also identified in lagoon sediments. These include free C 23-C 33 n-alkenes (CPI 5.4) Δ 2 sterens, Δ 3,5- and Δ N,22 -steradienes. The distributions of Δ 2-sterenes parallels that of the stanols in the bound fraction which exhibit a higher C 27-stanol/stenol ratio than that of the free fraction. The direct biological input stanols is suggested to explain this feature. A smooth distribution of C 25-C 35 n-alkanes (CPI-1.5), probably of microbial origin, is another characteristics of the bound lipids. Long chain n-alkan-2-ones and n-alkanals were present in the lagoon with distributions similar to those of n-alkanes and n-alkanols, respectively. n-Ketones are probably not produced in situ, but transported from soils. n-Aldehydes were only found in the bound fraction illustrating the protection from further degradation that binding affords to organic matter. In summary, tha unaltered algal and bacterial markers in the sapropel mud are consistent with the bioecology of the system, while in the coastal lagoon sediments a more advanced microbial decomposition of organic matter is observed particularly in the analysis of the bound fraction.

Trans -Monounsaturated Acids in a Marine Bacterial Isolate

A sedimentary bacterial isolate has been shown to contain trans-monounsaturated fatty acids (6% of the total fatty acids). The ratio of trans- to cis-acids in this isolate was in the range 3.2 to 7.6. The identification of trans-monounsaturated acids in a marine bacterium implied that the trans-acids which have been reported in recent sediments could derive, in whole or part, from direct bacterial input.