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At least 19 recordsLinked to original sources
PubMed2003

Simultaneous effects of environmental factors on motile Aeromonas dynamics in an urban effluent and in the natural seawater.

Seasonal dynamics of motile Aeromonas in a treated urban effluent and in natural seawater along the Sfax coast (Mediterranean sea, Tunisia) were measured over a year concurrently with seven environmental factors, and compared with those of faecal coliforms. Counts for Aeromonas from a standard plate count method, ranged from 1.48 x 10(5)CFU.100 ml(-1) to 2.2 x 10(8)CFU.100 ml(-1) in the effluent and from 7.9 x 10(3)CFU.100 ml(-1) to undetectable level in the surface marine waters. Contrary to faecal coliforms, the Aeromonas dynamics exhibited a seasonal distribution in seawater which was inverse of the seasonal distribution in the sewage: From the end of November 1998 to April 1999 (cold period), Aeromonas counts increased in the treated effluent, while it decreased very rapidly in seawater. From May to October (warm period), Aeromonas abundance decreased in the effluent but showed an increasing fluctuating trend in the marine waters with a maximum in late summer/early autumn when the temperatures were around 22-23 degrees C. Multiple correlation and regression analyses suggest, by the coefficient of determination (R(2)), that 42% of variance in Aeromonas number changes in the treated effluent, may be explained by only turbidity, radiation and Aeromonas density in the previous sample, while 37% of variance in marine ecosystem were explained by radiance and conductivity. Furthermore, the t statistics and their p values and the coefficient of partial determination (r(2)) indicated that radiance contributed the most (r(2)=0.3184, t=-3.2, p=0.0041) to the dynamics of motile Aeromonas in seawater, when combined with conductivity. The models relevant for changes in faecal coliforms abundance incorporated turbidity, radiance in the effluent and conductivity, pH, radiance, turbidity in coastal marine environment. These models explain 66% and 73% of the observed cell number fluctuation, with turbidity (r(2)=0.529, t=5.08, p=0.0001) and conductivity (r(2)=0.5407, t=4.97, p=0.0001) as dominant factors in the multivariate model proposed, respectively, for the two sampling sites. The results presented here suggest that the combination of negative effects of sunlight and conductivity in natural seawater mainly affects the colony-forming capacity and make the motile Aeromonas nonrecoverable during cold months.

Aeromonas↗
PubMed2001

Adsorption and uptake of Cu by Emiliania huxleyi in natural seawater.

Short-term kinetic experiments, carried out in natural coastal seawater (with predetermined background levels of trace metals and organic ligands, L) enriched with nitrate and phosphate, demonstrated that Emiliania huxleyi was able to uptake Cu very quickly. After 10 min of exposure (background Cu level in the inoculated cells: [Cu]total cellular = 9.3 x 10(-17) mol cell-1, [Cu]intracellular = 8.4 x 10(-17) mol cell-1, and [Cu]extracellular = 1.0 x 10(-17) mol cell-1) to a natural seawater which contained 29 nM total initial dissolved Cu concentration ([Cu]d) (29 nM [CuL] and 3.2 x 10(-13) M free Cu concentration, [Cu2+]) the intracellular Cu was already 28 x 10(-17) mol cell-1. This value corresponded to 85% of the intracellular metal observed in pseudoequilibrium conditions (after 24 h of exposure) and to 88% of the total metal sorption (adsorption plus uptake) after 10 min. In contrast, the external adsorption after 10 min was only 3.0 x 10(-17) mol cell-1 which corresponded to 60% of the extracellular metal in pseudoequilibrium conditions. Simultaneously occurred a very fast release of organic ligands (L) by E. huxleyi, the majority being identified by cathodic stripping voltammetry as glutathione. The production of exudates increased with both Cu concentration and exposure time. After 10 min of exposure, the production of exudates in a medium with 129 nM [Cu]d (72 nM [CuL] and 7.9 x 10(-13) M [Cu2+]) was 51 nM, about 42% of that observed in pseudoequilibrium. As the Cu complexes with the organic ligands present in the medium were very stable (logarithm of the conditional stability constant: 12.18 +/- 0.06) and the ligand concentration in the medium was relatively high (e.g. 123 nM CL in the medium with 129 nM initial [Cu]d after 10 min of exposure) most of the metal was organically bound in the medium.

Adsorption↗
PubMed1997

Salmonella DNA persistence in natural seawaters using PCR analysis.

The risks of false-positive responses were examined when using the polymerase chain reaction (PCR) method for the detection of Salmonella in the marine environment (water and shellfish). The degradation rates of DNA, both free and from dead Salmonella, were evaluated in natural seawaters maintained at 10 degrees and 20 degrees C, using PCR with Vir and invA primers. The DNA of dead Salmonella was detected up to 55 d in seawater collected in winter and stored at 10 degrees C. But in summer, the persistence was shorter: 10 d or even 2 d for a smaller inoculum (3 x 10(3) Salmonella ml-1). The role of the planktonic organisms present in spring and summer was pinpointed. For free DNA, the persistence times were shorter: from 2 to 4 d at 20 degrees C, and from 3 to 8 d at 10 degrees C showing that the nuclease activity of marine organisms is higher at warm temperatures. These data led us to recommend careful interpretations of direct PCR results, especially during cold periods and for samples collected close to terrestrial discharges of high concentrations of live, dead or lysed Salmonella. PCR is a rapid, specific and sensitive method, but should be applied with care to marine samples, in order to avoid false-positive responses.

Animals↗
PubMed2003

The effect of dissolved organic carbon on bacterial adhesion to conditioning films adsorbed on glass from natural seawater collected during different seasons.

Adhesion of three marine bacterial strains, i.e. Marinobacter hydrocarbonoclasticus, Psychrobacter sp. and Halomonas pacifica with different cell surface hydrophobicities was measured on glass in a stagnation point flow chamber. Prior to bacterial adhesion, the glass surface was conditioned for 1 h with natural seawater collected at different seasons in order to determine the effect of seawater composition on the conditioning film and bacterial adhesion to it. The presence of a conditioning film was demonstrated by an increase in water contact angle from 15 degrees on bare glass to 50 degrees on the conditioned glass, concurrent with an increase in the amount of adsorbed organic carbon and nitrogen, as measured by X-ray photoelectron spectroscopy. Multiple linear regression analysis on initial deposition rates, with as explanatory variables the temperature, salinity, pH and concentration of dissolved organic carbon (DOC) of the seawater at the time of collection, showed that the concentration of DOC was most strongly associated with the initial deposition rates of the three strains. Initial deposition rates of the two most hydrophilic strains to a conditioning film, increased with the concentration of DOC in the seawater, whereas the initial deposition rate of the most hydrophobic strain decreased with an increasing concentration of DOC.

Adhesiveness↗
PubMed2004

Maintenance of pathogenicity during entry into and resuscitation from viable but nonculturable state in Aeromonas hydrophila exposed to natural seawater at low temperature.

AIMS: To investigate the fate of Aeromonas hydrophila pathogenicity when cells switch, in nutrient-poor filtered sterilized seawater, between the culturable and nonculturable state. METHODS AND RESULTS: Aeromonas hydrophila ATCC 7966, rendered non culturable within 50-55 days of exposure to marine stress conditions, was tested for its ability to maintain haemolysin and to adhere to McCoy cells. Results showed that pathogenicity was lost concomitantly with culturability, whereas cell viability remained undamaged, as determined by the Kogure cell elongation test. However, this loss is only temporary because, following temperature shift from 5 to 23 degrees C, multiple biological activities of recovered Aer. hydrophila cells, which include their ability to lyse human erythrocytes and to attach and destroy McCoy cells were regained. During the temperature-induced resuscitation, constant total cell counts were observed. Moreover, no significant improvement in recovery yield was obtained on brain-heart infusion (BHI) agar plates amended with catalase. We suggest that in addition to the growth of the few undetected culturable cells, there is repair and growth of some mildly injured viable but nonculturable cells. CONCLUSIONS: The possibility that nonculturable cells of normally culturable Aer. hydrophila in natural marine environment may constitute a source of infectious diseases posing a public health problem was demonstrated. SIGNIFICANCE AND IMPACT OF THE STUDY: These experiments may mimic what happens when Aer. hydrophila cells are released in natural seawater with careful attention to the conditions in which surrounding waters gradually become warmer in late summer/early autumn.

Aeromonas hydrophila↗
PubMed2006

Bioremediation and toxicity determination of natural seawater polluted with weathered crude oil by salt-tolerant consortia in a SBR.

The aim of this research was to compare the bioremediation treatment of seawater polluted with two different concentrations of weathered crude oil (0.2 for experiment (a) and 1.14% for experiment (b), v/v) by salt-tolerant consortia enriched from the sludge of a refinery wastewater treatment facility, in a SBR. The use of a commercial bioremediation stimulant (S200) was also evaluated as an alternative to the traditional nitrogen and phosphorus supplement.

Bacteria↗
PubMed2002

Time-of-flight secondary ion mass spectrometry: characterisation of stainless steel surfaces immersed in natural seawater.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been employed to study the biofouling of stainless steel samples immersed in seawater. The aim of these characterisations was to understand the initial mechanisms of biomolecule adsorption for relatively short immersion times (from 0 to 24 h). The results show that: (i) there were unavoidable sample "precontaminations" on the surfaces, despite precaution during their preparation and manipulation (washing, drying and storing); (ii) the major peaks detected were the substrate ones whatever the immersion time [However, some organic (nitrogen and oxygen containing) and inorganic secondary ions appeared and grew with the immersion time.]; (iii) the surface contaminations, the nonuniformity of the adsorbed material so as and bacteria have been clearly observed by high-lateral resolution molecular ToF-SIMS mapping.

Bacteria↗
PubMed2004

Temperature and growth-phase effects on Aeromonas hydrophila survival in natural seawater microcosms: role of protein synthesis and nucleic acid content on viable but temporarily nonculturable response.

The behaviour of Aeromonas hydrophila in nutrient-poor filter-sterilized seawater was investigated at 23 and 5 degrees C with respect to its growth phase. At both temperatures, the culturable A. hydrophila population declined below the detection level (0.1 c.f.u. ml(-1)) after 3-5 weeks, depending on the initial physiological state of the cells. During the first week, starved A. hydrophila cells appeared more resistant to the seawater stress at 5 degrees C than cells initially in the exponential growth phase. This difference was not observed at 23 degrees C, where de novo protein synthesis seemed to be required for long-term adaptation of cells from the exponential growth phase. Over the duration of the experiments, intact and total cell concentrations were not significantly affected, indicating that bacteria had entered a so-called viable but nonculturable state (VBNC). However, the incubated bacteria rapidly became heterogeneous with respect to their nucleic acid content, and their cell size decreased faster at 23 than at 5 degrees C. Resuscitation of VBNC cells was attempted by a temperature shift from 5 to 23 degrees C without exogenous nutrient addition. Comparison of the growth rates of the stressed population and of the untreated bacteria growing in the same autoclaved initial cell suspension showed significantly faster growth for the stressed cells, suggesting that in addition to growth of the few culturable stressed cells, a proportion of injured cells became culturable.

Aeromonas hydrophila↗
PubMed2026

Seawater type shapes larval development, intestinal microbiota, and water quality in Macrobrachium rosenbergii.

Giant freshwater prawn (Macrobrachium rosenbergii) has high economic value and extensive aquaculture prospects, and larval quality critically restricts the sustainable development of the industry. To investigate the effects of different seawater sources on larval survival and growth, artificial seawater, natural seawater from Beibu Gulf (China) and East China Sea (China) were used as culture media to compare their influences on larval development and intestinal microbiota of M. rosenbergii. Significant intergroup differences were observed in cultivation outcomes. The larval emergence rate reached the maximum value of 52.1% in Group G (Beibu Gulf natural seawater), followed by 43.57% in Group R (artificial seawater), and only 36.4% in Group Z (East China Sea natural seawater), indicating distinct larval emergence gaps and a gradual decline in larval development efficiency. Intestinal microbiota analysis indicated that Pseudomonadota, Actinomycetota and Bacillota were the dominant phyla in all three groups. The relative abundance of Bacillota increased significantly in Group G on day 10. LEfSe analysis proved that this group owned the most stable microbial structure and highest community diversity, and pronounced structural fluctuations occurred in Group R, suggesting that intestinal microbial profiles can reflect larval developmental conditions. Correlation analysis showed that gut microbial composition was closely correlated with water environmental parameters, and microbial metabolic pathways were strongly associated with larval growth and development. This study indicates that natural seawater from the Beibu Gulf of China is more suitable for healthy larval cultivation of M. rosenbergii. Structural stability and diversity of intestinal microbiota are key factors affecting larval growth. The results offer theoretical references for optimizing artificial seawater formula and improving larval rearing efficiency.

16S rRNA↗
PubMed2004

Biotransformation and dissolution of petroleum hydrocarbons in natural flowing seawater at low temperature.

The objective of this study was to establish methods for controlled studies of hydrocarbon depletion from thin oil films in cold natural seawater, and to determine biotransformation in relation to other essential depletion processes. Mineral oil was immobilized on the surface of hydrophobic Fluortex fabrics and used for studies of microbial biodegradation in an experimental seawater flow-through system at low temperatures (5.9-7.4 degrees C) during a test period of 42 days. The seawater was collected from a depth of 90 m, and microbial characterization by epifluorescence microscopy, fluorescence in situ hybridization, and most-probable number analysis showed relatively larger fractions of archaea and oil-degrading microbes than in the corresponding surface water. Chemical analysis of hydrocarbons attached to the fabrics during the test period showed that n-alkanes (C10-C36) were decreased by 98% after 21 days, while naphthalenes were depleted by 99-100% during the same period. At the end of the period 4-5 ring polyaromatic hydrocarbon (PAH) compounds were removed by 82% from the fabrics. Analysis of the recalcitrant pentacyclic triterpane C30 17alpha(H),21beta(H)-hopane showed that the oil remained adsorbed to the fabrics during the test period. Comparison of depletion analysis with calculation of hydrocarbon dissolution in a flow-through system indicated that naphthalenes and smaller PAH compounds (alkylated 2-ring and 3-ring compounds) were removed from the fabrics by dissolution. The data further implied that depletion of n-alkanes and 4-5 ring PAH hydrocarbons were the result of biotransformation processes. PCR amplification of bacterial 16S rRNA genes from microbes adhering on the immobilized oil surfaces showed the dominance of a few bands when analysed in denaturing gradient gel electrophoresis (DGGE). Sequence analysis of DGGE bands revealed phylogenetic affiliation to the alpha- and gamma-subdivisions of proteobacteria and to the Chloroflexus-Flavobacterium-Bacteroides group.

Bacteria↗
PubMed1964

EFFECT OF CHELATING AGENTS ON THE GROWTH OF ESCHERICHIA COLI IN SEAWATER.

Jones, Galen E. (Scripps Institution of Oceanography, University of California, La Jolla). Effect of chelating agents on the growth of Escherichia coli in seawater. J. Bacteriol. 87:483-499. 1964.-Escherichia coli did not grow at 37 C, or grew only after a prolonged lag phase in filter-sterilized basal seawater medium (synthetic or natural seawater supplemented with glucose, NH(4)Cl, and K(2)HPO(4)). When this basal medium was enriched with 0.01% or less organic matter, such as casein hydrolysate, peptone, or yeast extract, growth always occurred after a short lag phase. Adding 10(-5)m cysteine or autoclaving the seawater gave a similar effect. A variety of organic chelating agents (histidine, glycine, methionine, glycylglycine, 8-hydroxyquinoline, thioglycolic acid, o-phenanthroline, disodium ethylenediaminetetraacetic acid, etc.) reversed the toxicity of filter-sterilized basal seawater medium in concentrations predictable from stability constants. Even metal-complexing agents such as Na(2)S(2)O(3), Na(2)S, and NaCN in appropriate concentrations reversed toxicity. The quality of the distilled water and the treatment of glassware had a significant effect on the growth of E. coli in basal seawater medium. It was concluded that iodate is probably not the toxic substance for E. coli in seawater, since relatively high concentrations were stimulatory. The inhibition resulting from the individual salts of synthetic seawater was proportional to their concentration; NaCl was most inhibitory. This toxicity is believed to be derived from trace impurities in the reagent-grade chemicals used to prepare synthetic seawater. Evidence was also found for the toxicity of heavy metals in natural seawater. Heavy metals in seawater appear to inhibit growth but not respiration.

Chelating Agents↗
PubMed2004

Toxicity of ammonia to three marine fish and three marine invertebrates.

Laboratory toxicity tests were performed to obtain more data on the toxicity of ammonia to saltwater organisms. The standards for in-stream ammonia limits in marine environments presently are based on toxicity tests involving both freshwater and saltwater organisms. Acute tests (48 and 96 h) were performed at 20 degrees C, and chronic tests (7 days) were performed at 25 degrees C. Synthetic seawater and natural seawater from the Chesapeake Bay were used and compared. Included among the organisms tested were sheepshead minnow (14 days old), summer flounder (2 months old), Atlantic silverside (14 days old), mysid shrimp (less than 2 days old), ghost shrimp (10 days old), and quahog clam (9 months old). Based on these results, it seems the chronic criterion for ammonia in marine environments could be increased from 0.035 to 0.081 mg/L un-ionized ammonia, which would, of course, increase the chronic limit for total ammonia under typical saltwater conditions by a factor of 2.31. No difference was observed in the toxicity of ammonia in natural water compared to synthetic water for both the summer flounder and Atlantic silverside. Furthermore, the Atlantic silverside became more sensitive to ammonia as the salinity was increased from 14 to 22 ppt, but exhibited no change in toxicity response from 22 to 30 ppt.

Ammonia↗
PubMed1983

Purification of sea urchin sperm bindin by DEAE-cellulose chromatography.

A procedure for purifying bindin from sperm of the sea urchin Strongylocentrotus purpuratus is presented in detail. The impure bindin, dissolved in 4 M urea, 50 mM sodium phosphate, pH 6.6, is adsorbed to DEAE-cellulose and eluted wit 4 M urea, 650 mM sodium phosphate, pH 6.6. The purified bindin is not contaminated with tubulin or histone HI. A precipitate of this DEAE-purified bindin, made by dialysis into Ca2+-free seawater and natural seawater, is a species-specific agglutinin of unfertilized eggs. This method of obtaining consistently pure preparations of bindin will aid in the analysis of its role in fertilization.

Animals↗
PubMed2001

Chemiluminescence method with potassium permanganate for the determination of organic pollutants in seawater.

A chemiluminescence method with potassium permanganate was developed for use as an indicator of organic pollutants in fresh water. This method could be applied to the determination of organic pollutants in seawater as well. However, the flow chemiluminescence method suffered from the interference of chloride ions at the same concentration of seawater because of the production of manganese dioxide in the oxidation of chloride ions with permanganate. The conditions (concentrations of potassium permanganate and sulfuric acid and sample volume, i.e. flow injection method) were chosen to minimize the interference of chloride ions. The chemiluminescence method shows a good correlation with the chemical oxygen demand method on fresh water added artificial sea salt and seawater samples. Natural seawater was analyzed by the chemiluminescence method. The results obtained were compared with those obtained by chemical oxygen demand under the alkaline condition and total organic carbon methods. The chemiluminescence method has higher sensitivity and reproducibility than the conventional chemical oxygen demand and total organic carbon methods.

Chromatography, Liquid↗
PubMed2002

Determination of V(IV) and V(V) by electrothermal atomic absorption spectrometry following selective solid-phase extraction and the study on the change in the oxidation state of vanadium species in seawater during the sample storage.

The changes in the oxidation state of vanadium in artificial and natural seawater samples were studied by electrothermal atomic absorption spectrometry (ETAAS) with a direct injection of a resin suspension. V(IV) and V(V) were extracted as the complex with Chromazurol B and with N-cinnamoyl-N-2,3-xylylhydroxylamine, respectively, using a suspension of an anion-exchange resin and determined by ETAAS independently. The detection limits of both methods were 0.02 ng ml(-1) for 40 ml of a sample solution. The recovery tests for an artificial seawater sample spiked with V(IV) and/or V(V) were carried out carefully. The results showed that the recoveries of V(IV) or V(V) were 99.2-109% and the standard deviations were 1-6%. The total V was also determined after V(V) was reduced by ascorbic acid. In artificial seawater at pH 7.8, V(V) was stable but V(IV) was oxidized rapidly. In acidified artificial seawater (pH 2.0), V(IV) was oxidized slowly but only a small tendency of such reduction of V(V) was observed. In a natural seawater sample, V(IV) was not detected. The acidification of the natural seawater sample resulted in the reduction of V(V).

Hydrogen-Ion Concentration↗
PubMed1984

Metabolic and ultrastructural response to glucose of two eurytrophic bacteria isolated from seawater at different enriching concentrations.

Two marine bacteria, an Acinetobacter sp. (strain GO1) and a vibrio sp. (strain G1), were isolated by extinction dilution and maintained in natural seawater supplemented with nitrogen, phosphorus, and glucose at 0.01 and 10 mg of glucose carbon per liter above ambient monosaccharide concentrations, respectively. After 3 days in unsupplemented natural seawater, growth in batch culture with glucose supplements was determined by changes in cell numbers and glucose concentration. The exponential growth of the Acinetobacter strain with added glucose was indistinguishable from that in natural seawater alone, whereas that of the Vibrio strain was more rapid in the presence of glucose supplements, suggesting that the Acinetobacter strain preferred the natural organic matter in seawater as a carbon source. The ultrastructure for both isolates was unaffected by glucose supplements during exponential growth, but there were marked changes in stationary-phase cells. The Vibrio strain formed polyphosphate at 10 mg of glucose carbon per liter, whereas poly-beta-hydroxybutyrate formation occurred at 100 mg and became excessive at 1,000 mg, disrupting the cells. In contrast, the Acinetobacter strain elongated at 100 and 1,000 mg of glucose carbon per liter but failed to show poly-beta-hydroxybutyrate formation. The diversity of responses shown here would not have been detected with a single concentration of substrate, often used in the literature to characterize both pure and natural populations of marine bacteria.

Acinetobacter↗
PubMed2000

Photoreduction and evolution of mercury from seawater

The photoreduction of mercury (Hg2+ to Hg0) in natural seawater was investigated by means of a radiotracer (203Hg2+) solution exposed to natural and simulated sunlight. Different light regimes (dark, natural daylight, and a solar simulator), and dissolved organic carbon (DOC) levels from commercially available humic acids concentrations, were tested in the laboratory to evaluate the possibility of occurrence of the reaction in the environment. The natural seawater prepared accordingly to each experimental condition was continuously purged of the Hg0 formed, which was then re-oxidised in an acid trap and determined. The use of a solar simulator permitted the test of light intensity and wavelength dependence of the process under investigation. The reaction is dependent on the concentration of DOC in the experimental solution, increasing light intensity and decreasing wavelength. Reduction rates were in the range of 0.04-2.2% h(-1) for the DOC concentrations and light regimes tested. The process might have geochemical implications for the cycling of mercury around the air-sea interface.

Journal Article↗