Occurrence of Vibrio spp. in blue mussels (Mytilus edulis) from the German Wadden Sea

The present study aimed at determining the contamination of blue mussels grown in Germany with relevant bacterial organisms. Seasonal variations were examined. For that purpose, mussel samples were taken regularly between June 2004 and May 2005 in seven shellfish-growing areas of the German Wadden Sea. A total of 90 samples were analysed. The analysis included the compulsory microbiological parameters Escherichia coli and Salmonella spp., as well as the determination of the contamination with Vibrio spp. Although the analysed mussels complied with the legislation in force, potential human pathogens were detected in a wide range of samples. Vibrio spp. was detected in 74.4% of the samples analysed in this study. Among Vibrio isolates, Vibrio alginolyticus was the species most frequently detected (51.2%), followed by Vibrio parahaemolyticus (39.5%). Vibrio vulnificus was detected in 3.5% of the samples. V. parahaemolyticus and V. vulnificus were not found in samples collected at low water temperatures. The results indicate that blue mussels from shellfish-growing areas in the German Wadden Sea regularly contain pathogens relevant to public health. They also show that E. coli is not a reliable indicator for the contamination with Vibrio spp. To improve consumer protection, it therefore seems necessary to extend the analysis of mussels for direct human consumption by additional parameters.     

Occurrence and characterization of Aeromonas spp. in mussels from the Adriatic Sea

Samples of mussels (Mytilus galloprovincialis) were collected from natural beds on the Adriatic Sea in front of Ancona Province (Marches, Central Italy) officially recognized for human consumption. The mussels were analyzed to evaluate the prevalence of Aeromonas spp. pathogenic strains. Out of 144 samples, 32 Aeromonas strains were isolated and 12 showed virulence and enterophatogenicity on mice. Isolates were also examined to check their sensitivity to different antimicrobial agents. All isolates were sensitive to imepenem, neomycin, ciprofloxacin, tetracycline, oxytetracycline, doxycicline, chloramphenicol, polymyxin B, and colistin sulfate, but resistant to penicillin, carbenicillin, cephalotin, sulfamethoxazole, lincomycin, novobiocin, and rifampicin. Multiple resistance to antimicrobial agents with different mechanism of action was observed. Owing to the high occurrence of pathogenic Aeromonas strains, the risk of developing human infections by eating raw or undercooked mussels is envisaged.     

Occurrence of Vibrio and other pathogenic bacteria in Mytilus galloprovincialis (mussels) harvested from Adriatic Sea, Italy.

Sixty-two samples of Mytilus galloprovincialis (mussels) harvested from approved shellfish waters in the Adriatic Sea were examined for the presence of Vibrio, Salmonella, Campylobacter, and verocytotoxin producing Escherichia coli. Vibrio spp. were isolated from 48.4% of samples; the species most frequently found were V. alginolyticus (32.2%) and V. vulnificus (17.7%), followed by V. cincinnatiensis (3.2%), V. parahaemolyticus (1.6%), V. fluvialis (1.6%) and V. cholerae non-O1 (1.6%). V. parahaemolyticus resulted negative to Kanagawa-phenomenon and to PCR amplification of tdh gene. V. cholerae resulted negative to PCR amplification of sto gene. No Salmonella, Campylobacter, or E. coli verocytotoxin-producing strains were isolated. The results of this study suggest the potential risk of ingesting raw or undercooked mussels due to the frequent presence of potentially pathogenic Vibrio species.     

Geographical and annual variation in lipophilic shellfish toxins from oysters and mussels along the south coast of Korea

To better understand critical aspects of diarrhetic shellfish poisoning (DSP) occurrence in a chief producing region of bivalves in Korea, the geographical and annual variation of DSP toxins and other lipophilic toxins in mussels (Mytilus galloprovincialis) and oysters (Crassostrea gigas) were investigated by liquid chromatography-tandem mass spectrometry in an area on the south coast of Korea from 2007 to 2009. The total lipophilic shellfish toxin (LST) levels in bivalves showed geographical and annual variations. LSTs were detected mostly in the hepatopancreas of mussels from Jinhae Bay throughout the entire year, except in November and December of 2007, but were almost undetectable in all samples during the entire year in 2009. The peak DSP toxin (okadaic acid plus dinophysistoxin 1) levels in the hepatopancreas of mussels from Jinhae Bay and the Tongyeong region were 945.3 and 37.6 ng/g, respectively. The DSP toxin content was about 10 times higher in mussels than in oysters collected from the same region. The major toxins in bivalves were okadaic acid and dinophysistoxin 1; however, pectenotoxin 2 or yessotoxin was occasionally detected as a major component. The results of a quantitative analysis of phytoplankton showed that Dinophysis acuminata was the most probable source of the LSTs, with the exception of yessotoxin. When the highest DSP toxin level was measured (945.3 ng/g in the hepatopancreas of mussels from Jinhae Bay), the toxin concentration in whole mussel tissue was calculated to be 114.0 ng/g. The calculated highest DSP toxin level in whole oyster tissue from both regions was 15.0 ng/g. The calculated maximum toxicities in whole mussel and oyster tissues were lower than the regulatory limit (160 to 200 ng/g) in Korea, the European Union, and the United States. Korean oysters (242 samples) and mussels (214 samples) were thus deemed safe for consumption. But because such variation was detected in a relatively small area of the coast, it is possible that at some locations or during a specific period LST levels could exceed the standard and a few consumers could be at risk of experiencing DSP.     

Heavy metals in mussels (Mytilus galloprovincialis) from the lonian Sea, Italy

Concentrations of six heavy metals (Hg, Pb, Cd, Cr, Zn, and Sn) were determined in mussels (Mytilus galloprovincialis) collected between June and September 1997 from 10 locations along a sound formed by two inlets (Mar Piccolo) near the Gulf of Taranto (Ionian Sea, Italy). The average concentrations of the heavy metals found in mussels samples were 0.15 mg/kg for Hg, 1.19 mg/kg for Pb, 0.64 mg/kg for Cd, 0.31 mg/kg for Cr, 5.15 mg/kg for Zn, and 0.54 mg/kg for Sn. The concentrations of heavy metals in mussels from the first inlet did not differ greatly from those observed in mussels from the second inlet. The concentrations of heavy metals in the mussels analyzed were below acceptable levels for human consumption.     

Identification of polybrominated dibenzo-p-dioxins in blue mussels (Mytilus edulis) from the Baltic Sea

Polybrominated dibenzo-p-dioxins (PBDDs) are known to be formed as byproducts in connection with the manufacture and combustion of products containing brominated flame retardants. However, to date little is known about the occurrence of PBDDs in biological samples. The aim of the present investigation was to examine the presence of PBDDs in blue mussels (Mytilus edulis) from the Baltic Sea employing a procedure adapted for dioxin analysis. Two triBDDs (1,3,7-triBDD and 1,3,8-triBDD) were identified in biota here for the first time. This identification was based on accurate mass determination and comparison of retention times on three gas chromatographic columns of different polarities (PTE 5, SP-2331, and OV1701/heptakis) with synthesized standards, together with comparisons of electron capture negative ionization (ECNI) and electron ionization (EI) mass spectra. In addition, five PBDDs and one polybrominated dibenzofuran (PBDF) were tentatively identified; altogether, one diBDD, three triBDDs, three tetraBDDs, and one triBDFwere detected in the blue mussels. To our knowledge this is the first time PBDDs have been identified in biota of the Baltic Sea. The sigma triBDD concentration in the blue mussels was estimated to be 170 ng/g lipids. The origin of these PBDDs remains unclear, but a plausible hypothesis could be biogenic formation in the marine environment.     

Survey of levels of cadmium in oysters,mussels, clams and scallops from the Pacific Northwest coast of Canada

Field and retail collections of bivalves from the Pacific Northwest, Canada, were analysed for cadmium concentrations by atomic absorption spectrophotometry (AAS). Both collections of varnish (Nuttallia obscurata) and manila (Venerupis philippinarum) clams contained cadmium concentrations of less than 0.5 µg g^?1, well below international safety guidelines of 1 and 2 µg g^?1 wet weight cadmium for the European and Hong Kong markets, respectively, as well as the 2 µg g^?1 safety guideline set by the Codex Alimentarius Commission (CAC). Cadmium concentrations in retail collections of the Pacific oyster, Crassostrea gigas, were generally above 2 µg g^?1 wet weight (range = 1.5–3.56 µg g^?1). Retail collections of the mussel, Mytilus spp., contained cadmium concentrations below the 2 µg g^?1 wet weight guideline, but not always the 1 µg g^?1 limit (range = 0.15?1.8 µg g^?1). However, field collections of Mytilus spp. contained cadmium concentrations between 0.35 and 4.00 µg g^?1 wet weight, and depending on sampling location, concentrations exceeded the CAC guidelines by more than two-fold. Locations where mussels had high cadmium concentrations correlated with regions that had previously reported high values for cadmium in Pacific oysters (r = 0.65; p < 0.05). Of the various shellfish analysed, the four species of scallops, Chlamys hastata, C. rubida, Crassadoma gigantea, and Patinopecten yessoensis, contained the greatest concentrations of cadmium, in excess of 5 µg g^?1 wet weight (range = 4.97–8.98 µg g^?1) with the greatest concentrations determined for C. gigantea. Cadmium concentrations in shellfish from the Pacific Northwest are greater than values reported for shellfish from other regions of the world and consumers need be aware of Health Canada consumption guidelines for shellfish from this region.     

Polycyclic aromatic hydrocarbons in mussels (Mytilus galloprovincialis) from the Ionian Sea, Italy

Concentrations of eight polycyclic aromatic hydrocarbons (PAHs) (phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[ghi]perylene) were determined in mussels (Mytilus galloprovincialis) collected between June and September 1995 from 10 locations along a sound of sea formed by two inlets (Mar Piccolo) close to the Gulf of Taranto (Ionian Sea, Italy). In mussels the concentrations of total PAHs were between 14.8 and 645.3 microg/kg wet weight. Among the single identified compounds, the predominance of phenanthrene (29.5 microg/kg wet weight) and anthracene (64.7 microg/kg wet weight) was evident. Another relevant pollutant was pyrene (18.4 microg/kg wet weight) followed by fluoranthene (7.2 microg/kg wet weight), whereas the other compounds showed low levels. The mussels that showed the highest total concentrations of PAHs were collected from stations affected by stronger human activities (industrial fallout, urban wastewaters, and contaminants transported via riverine discharge). Our results were similar to those found in areas classified as moderately polluted. This observation suggests the need for an increased effort in controlling sources of pollution in this area recognized as one of the most productive mussel-farming areas in the Italy.     

Presence of pathogenic Vibrio parahaemolyticus strains in mussels from the Adriatic Sea, Italy

Samples of mussels (Mytilus galloprovincialis) collected from approved coastal sites located on the Adriatic Sea (Central Italy) were examined for the presence of Vibrio parahaemolyticus and the occurrence of pathogenic strains. The isolation of the micro-organisms was performed using a standard method. A biochemical protocol was applied for the identification of the isolates. Polymerase chain reaction (PCR) was used to confirm the identification of the strains and to detect the tdh and trh genes. The Kanagawa phenomenon was assayed as phenotypic marker of thermostable direct hemolysin (TDH) toxin. The urease activity was assayed as phenotypic marker of trh gene. The protease activity and the cytotoxicity of strains were examined to identify other potential virulence factors. Thirty-five V. parahaemolyticus strains were isolated out of 144 samples. The tdh and trh genes were in one and three isolates, respectively. All strains, independent of the presence of tdh and trh genes, showed protease activity and cytotoxicity. Due to the occurrence of pathogenic V. parahaemolyticus, the potential risk of eating raw or undercooked mussels is envisaged.     

Isomeric distribution and rapid determination of trans-octadecenoic acids in German brands of partially hydrogenated edible fats

The determination of trans fatty acids (TFA), in particular trans-octadecenoic acids, in edible fats is of current interest, since just in the last years a variety of negative physiological effects has been related to TFA. A main source of C18:1 trans fatty acids are partially hydrogenated fats. Besides the total content of trans-octadecenoic acids, their isomeric distribution seems to be even more important, as fats of different origin, e.g. partially hydrogenated fats and ruminant fats, possibly show different physiological properties. In this study, 46 margarines and 16 shortenings and cooking fats, purchased in August of 1994, were analyzed for trans-octadecenoic acid isomers by a two-step method (Ag-TLC/HRGC). The mean relative isomeric distributions (g/100 g TFA) of both groups determined with a 100 m-column were comparable, with Δ9 and Δ10 being the main isomers. By repeated analysis of 15 brands between August of 1994 and January of 1996, the mean total C18:1 TFA content was found to have decreased in these margarines (n = 8) from 9.58% to 4.62% but not in shortenings/cooking fats (n = 7; 11.62% to 11.92%). The relative isomeric distribution was not affected in both groups. To avoid the problem of overlaps between cis-and trans-C18:1 isomers with GC analysis, formulae for the rapid determination of total C18:1 TFA contents in margarines and shortenings/cooking fats from direct GC data were statistically derived. Thus, applying these formulae and considering the mean relative distributions, absolute contents of all individual isomers of trans-octadecenoic acids can rapidly be determined from direct GC.     

Hydroxylated and methoxylated brominated diphenyl ethers in the red algae Ceramium tenuicorne and blue mussels from the Baltic Sea

Methoxylated polybrominated diphenyl ethers (MeO-PBDEs) and hydroxylated PBDEs (OH-PBDEs) have recently been identified in fish and wildlife from the Baltic Sea. Both OH-PBDEs and MeO-PBDEs are known natural products, while OH-PBDEs also may be metabolites of PBDEs. The aim of the present study was to determine if the red macroalga Ceramium tenuicorne could be a source for MeO- and OH-PBDEs in the Baltic environment. Blue mussels (Mytilus edulis) from the same area were also investigated for their content of MeO- and OH-PBDEs. Seven OH-PBDEs and four MeO-PBDEs were present both in the red macroalga and the blue mussels. The mussels also contained a monochlorinated OH-tetraBDE. One of the compounds, 6-methoxy-2,2',3,4,4',5-hexabromodiphenyl ether, has never been reported to occur in the environment. The identification was based on comparison of relative retention times with reference standards, on two gas chromatographic columns of different polarities, together with comparisons of full-scan electron capture negative ionization (ECNI) and electron ionization (EI) mass spectra. It is shown that MeO-PBDEs and OH-PBDEs are present in algae, but at this stage it could not be confirmed if the compounds are produced by the alga itself or by its associated microflora and/or microfauna.     

Organotin compounds in the liver tissue of marine mammals from the Polish coast of the Baltic Sea

Butyltins (BTs) and phenyltins (PhTs) were determined in the livers of marine mammals found by-caught or stranded along the Polish coast of the Baltic Sea. During the investigation an original analytical method was developed. Butyltin compounds were detected in all the liver samples, whereas phenyltins were not detected in any of the samples. The total concentrations of BTs ranged from 43.9 to 7698 ng(Sn) x g(-1) dry weight. Age-related trends to accumulate BTs in immature porpoises were found. At the same time there were no male-female differences in BTs concentrations observed. No statistically significant spatial distribution differences were found between the locations corresponding to the open Baltic Sea waters and inside the Gulf of Gdańsk, which is characterized by high maritime activity. In comparison to butyltin levels in marine mammals from other geographic regions, the samples analyzed indicate a significant degree of tributyltin pollution along the Polish coast of the Baltic Sea. On the basis of a literature review, higher BT levels are usually found in waters close to highly industrialized areas, such as Japan, Hong Kong, and the United States.     

Occurrence of chlorogenic acids in potatoes

Ten varieties of potato cultivated under the same conditions were analyzed for the occurrence of chlorogenic acids by high performance liquid chromatography. 3-O-caffeoylquinic acid (n-chlorogenic acid) is the predominant compound with 22-71 ppm, (on average of 41 ppm) depending on variety. 4-O-caffeoylquinic acid (phi 11 ppm), 5-O-caffeoylquinic acid (phi 7 ppm), 3,4-dicaffeoylquine acid (phi 3 ppm), and at times 3,5-dicaffeoylquinic acid (in traces) were also demonstrated. Caffeic acid compounds are not distributed uniformly in the potato tuber. They occur in strongly decreasing concentration from the outer sections to the inner ones. About 50% of these compounds are located in the potato peel and the adjoining tissue.     

Occurrence of perfluoroalkyl compounds in surface waters from the North Pacific to the Arctic Ocean

Perfluoroalkyl compounds (PFCs) were determined in 22 surface water samples (39-76°N) and three sea ice core and snow samples (77-87°N) collected from North Pacific to the Arctic Ocean during the fourth Chinese Arctic Expedition in 2010. Geographically, the average concentration of ∑PFC in surface water samples were 560 ± 170 pg L(-1) for the Northwest Pacific Ocean, 500 ± 170 pg L(-1) for the Arctic Ocean, and 340 ± 130 pg L(-1) for the Bering Sea, respectively. The perfluoroalkyl carboxylates (PFCAs) were the dominant PFC class in the water samples, however, the spatial pattern of PFCs varied. The C(5), C(7) and C(8) PFCAs (i.e., perfluoropentanoate (PFPA), perfluoroheptanoate (PFHpA), and perfluorooctanoate (PFOA)) were the dominant PFCs in the Northwest Pacific Ocean while in the Bering Sea the PFPA dominated. The changing in the pattern and concentrations in Pacific Ocean indicate that the PFCs in surface water were influenced by sources from the East-Asian (such as Japan and China) and North American coast, and dilution effect during their transport to the Arctic. The presence of PFCs in the snow and ice core samples indicates an atmospheric deposition of PFCs in the Arctic. The elevated PFC concentration in the Arctic Ocean shows that the ice melting had an impact on the PFC levels and distribution. In addition, the C(4) and C(5) PFCAs (i.e., perfluorobutanoate (PFBA), PFPA) became the dominant PFCs in the Arctic Ocean indicating that PFBA is a marker for sea ice melting as the source of exposure.     

Levels of metals in reared mussels from Taranto Gulf (Ionian Sea,Southern Italy)

Samples of Mytilus galloprovincialis were collected monthly during the period July 1999–June 2000 from two mussel culture areas influenced by urban and industrial wastes. These stations, subjected to different environmental impact conditions, are located in the coastal area of Taranto Gulf (Ionian Sea, Southern Italy). Metals (Cd, Cu, Pb, Zn, Fe and As) were determined by atomic absorption spectrophotometry (AAS) in the whole soft tissue of mussels. Seasonal changes in metal concentrations were observed. Metals exhibited maximum values in later winter–early spring, followed by a progressive decrease during the summer.     

The problem of selective determination of PSP toxins in mussels

Levels of paralytic shellfish poisoning (PSP) toxins in shellfish are routinely determined by mouse bioassay. In order to improve the qualitative and quantitative determination of PSP toxins, chromatographic techniques with fluorescence detection have been developed. These HPLC methods and the HPLC/MS coupling were used to determine a second PSP toxin which was found, in addition to saxitoxin, in canned Spanish mussels. These canned mussels were rejected in 1986 by the German food control because PSP concentrations were too high. It has been shown that these samples contained mainly dc-saxitoxin.     

Occurrence of perfluorooctane sulfonate and other perfluorinated alkylated substances in harbor porpoises from the Black Sea

Perfluorooctane sulfonate (PFOS) and other perfluorinated alkylated substances (PFAS) were determined in liver, kidney, muscle, brain, and blubber samples of 31 harbor porpoises (Phocoena phocoena relicta) of different age and sex stranded along the Ukrainian coast of the Black Sea. In all individuals and in all tissues, PFOS was the predominant PFAS, accounting for on average 90% of the measured PFAS load. PFOS concentrations were the highest in liver (327+/-351 ng/g wet wt) and kidney (147 +/-262 ng/g wet wt) tissue, and lower in blubber (18+/-8 ng/g wet wt), muscle (41+/-50 ng/g wet wt), and brain (24 +/-23 ng/g wetwt). No significant differences could be determined between males and females, nor between juvenile and adult animals (p > 0.05). Perfluorononanoic acid, perfluorodecanoic acid, perfluoroundecanoic acid, and perfluorododecanoic acid could be detected in liver tissue of approximately 25% of the individuals. Perfluorobutane sulfonate, perfluorobutanoic acid, and perfluorooctanoic acid were not detected in any of the porpoise livers. Although we investigated a potential intraspecies segregation according to the source of prey, using stable isotopes, no statistically significant correlation between PFOS concentrations and stable isotopes could be determined. It is, however, noteworthy that the contamination by PFOS in the Black Sea harbor porpoises is comparable to levels found in porpoises from the German Baltic Sea and from coastal areas near Denmark and, therefore, might pose a threat to this population.     

Metal content determination in four fish species from the Adriatic Sea

Concentrations of As, Cd, Cu, Hg and Pb were measured by atomic absorption spectrometry (AAS) in muscle tissues of four fish species: anchovy (Engraulis encrasicholus), mackerel (Scomber japonicus), red mullet (Mullus surmuletus) and picarel (Spicara smaris) from the Croatian waters of the Adriatic Sea during 2008 and 2009. Metal levels measured in anchovy were in the following ranges (mg kg⁻¹): As 0.01–54.8, Cd 0.001–0.02, Cu 0.001–6.29, Hg 0.001–0.52 and Pb 0.001–0.34 mg kg⁻¹. Metal ranges in red mullet were (mg kg⁻¹): As 0.01–70.9, Cd 0.002–0.85, Cu 0.001–57.3, Hg 0.001–2.07 and Pb 0.001–0.27 mg kg⁻¹. Metal level ranges measured in mackerel were (mg kg⁻¹): As 0.01–36.4, Cd 0.001–0.1, Cu 0.001–15.9, Hg 0.001–0.78 and Pb 0.002–0.24 mg kg⁻¹. In picarel, metal level ranges were (mg kg⁻¹): As 0.01–54.6, Cd 0.001–0.1, Cu 0.08–32.9, Hg 0.001–0.207 and Pb 0.001–0.46 mg kg⁻¹. Significant differences in metal concentrations were found among fish species. The results presented on metal contents in the examined species give an indication of the environmental conditions. Concentrations of Cd, Cu, Hg and Pb obtained were far below the established values by the European Community regulations. However, arsenic levels found in red mullet were higher than the recommended legal limits for human consumption and as such may present a human health issue.     

Occurrence of giardia cysts in mussels (Mytilus galloprovincialis) destined for human consumption

Between January and June 2004, a total of 200 nondepurated mussel samples of the Galician coast (northwest Spain) were examined for Giardia cysts with a direct immunofluorescence antibody test. Giardia cysts were found in mussels from all of the estuaries studied, with an overall rate of contamination of 41.5%. There was relation between the presence of Giardia cysts, the microbiological contamination (expressed as most probable number of Escherichia coli) detected in the samples, and the harvesting area. This is the first work that describes the presence of Giardia cysts in mussels (Mytilus galloprovincialis) destined for human consumption.