To examine whether there is a relationship between the degree of Campylobacter contamination observed in product lots of retail Icelandic broiler chicken carcasses and the incidence of human disease, 1,617 isolates from 327 individual product lots were genetically matched (using the flaA short variable region [SVR [) to 289 isolates from cases of human campylobacteriosis whose onset was within approximately 2 weeks from the date of processing. When there was genetic identity between broiler isolates and human isolates within the appropriate time frame, a retail product lot was classified as implicated in human disease. According to the results of this analysis, there were multiple clusters of human disease linked to the same process lot or lots. Implicated and nonimplicated retail product lots were compared for four lot descriptors: lot size, prevalence, mean contamination, and maximum contamination (as characterized by direct rinse plating). For retail product distributed fresh, Mann-Whitney U tests showed that implicated product lots had significantly (P = 0.0055) higher mean contamination than nonimplicated lots. The corresponding median values were 3.56 log CFU / carcass for implicated lots and 2.72 log CFU / carcass for nonimplicated lots. For frozen retail product, implicated lots were significantly (P = 0.0281) larger than nonimplicated lots. When the time frame was removed, retail product lots containing Campylobacter flaA SVR genotypes also seen in human disease had significantly higher mean and maximum contamination numbers than lots containing no genotypes seen in human disease for both fresh and frozen product. Our results suggest that cases of broiler-borne campylobacteriosis may occur in clusters and that the differences in mean contamination levels may provide a basis for regulatory action that is more specific than a presence-absence standard.
Author: admin
Regular seafood consumption is associated with beneficial health effects. This book reviews the research on seafood and health, the use and quality aspects of marine lipids and seafood proteins as ingredients in functional foods and consumer acceptance of (marine) functional food. The first chapter covers novel merging areas where seafood may prevent disease and improve health such as in cognitive development, mental health, cancer, allergy and oxidative stress are highlighted. Cases where nutrients in seafood may have health protective effects such as in proteins, peptides, amino acids, selenium, chitosan, glucosamine and chondroitin sulphate are also discussed. The next chapters cover quality aspects of marine lipids and seafood proteins as ingredients in functional foods. Lipids and proteins must have and retain a high quality so that the sensory and functional properties and the shelf life of the final product are acceptable. The methods used for processing marine lipids and proteins, are discussed as well as the different factors that can affect their quality in functional foods. The book then concentrates on factors related to consumers' attitudes, knowledge and awareness of functional foods. There are variations in types of carrier products and of demographic and cross-cultural factors in acceptance of functional foods. Finally, the book discusses challenges for small and medium enterprises to commercialize healthy nutrition. Variations in characteristics, capabilities, challenges and opportunities in the marketplace are presented using a Nordic study as reference.
The high mortality commonly observed during the early life stages of intensively reared halibut (Hippoglossus hippoglossus L) is believed to be caused by eg opportunistic bacteria. However, the impact of particular bacterial species is poorly defined and still remains disputable. The study describes the bacterial diversity in the gastrointestinal tract of halibut larvae in a large number of incubators at a commercial production site. The overall success of larvae was found to be highly variable and analysis of the gut microbiota revealed high variation of the cultivable part as well as the bacterial community of surface sterilized larvae analyzed by denaturing gradient gel electrophoresis (DGGE) or PCR amplified 16s rDNA products. Analysis of the bacterial community of unfed yolk sac larvae revealed higher diversity than previously reported, with Marinomonas, Marinobacter, Aeromonas and Shewanella dominating the community structure. There are indications that Marinomonas is found only in the overall most successful first feeding larvae of the period where the Vibrio group dominated the bacterial community together with Shewanella. Vibrio wodanis was identified as a part of the bacterial community of feeding larvae that yielded the poorest overall success of the period. α-Proteobacteria, not previously reported in halibut, were also found as a part of the bacterial community of first feeding larvae. The diverse bacterial community was only partly reflected in the cultivable part which, however, may reflect the dominating bacterial groups of the highly heterogeneous bacterial community of larvae in the production system as a whole. The bacterial community of the Artemia was found to be highly variable in different samples collected through the period. Only a small part of the different groups observed in the bacterial community of surface sterilized larvae was reflected in the cultivable part which was dominated by highly variable groups in different samples of Artemia. Also, the numbers of cultivable bacteria were found to positively correlate with jaw deformation of unfed yolk sac larvae as well as incomplete metamorphosis of feeding larvae.
To investigate a possible speciation event within the redfish (Sebastes mentella) complex in the Irminger Sea, we examined genetics, traditional morphology, geometric morphometrics and meristics of individuals sampled throughout the Sea. Tissue samples from 1901 fish were collected in 1995 and 1996 and from 1999 to 2002, and the fish were genotyped at nine microsatellite loci, two of which were developed for this study. Individual-based genetic analyzes showed that two different gene pools exist in the Irminger Sea. Although these groups overlap extensively geographically, they segregate according to depth: those above and below 550 m. This signal of genotype distinction with depth was evident in both the earlier and later sampling. Historical imprints in the genetic data indicated that the redfish in the Irminger Sea are likely to represent a case of an incipient speciation event that began in allopatry during the Pleistocene glaciations followed by secondary contact. Although hybridization was observed between groups, an analysis of traditional and geometric morphometrics and of meristic variables suggested that restricted gene flow between the currently parapatric deep- and shallow-mesopelagic incipient species may be maintained by ecological isolation mechanisms.
Cod (Gadus Morhua) muscle proteins were solubilized using alkaline treatment of the muscle. Solutions of similar protein composition were obtained between pH 10.5 and 12.0, however, pH> 11 was required for optimal yield. Addition of salt (up to 0.25 M NaCl) did not affect protein yield or composition. Light scattering showed that a significant fraction of the proteins was present as large self similar and flexible aggregates. When the pH was decreased below 10, gelation was observed below a critical temperature of about 25 ° C, which could be reversed by heating. Slow irreversible aggregation was also observed leading to coarsening and syneresis of the gels or precipitation at higher temperatures. The rate of irreversible aggregation increased with decreasing pH and was fast below pH 8. Homogeneous thermo-reversible self supporting gels that were stable for a period of days could be prepared without heating at a narrow pH range between 8.5 and 9.5.
Myosin was extracted from Atlantic Cod (Gadus morhua) using different methods resulting in small aggregates of pure myosin. These aggregates consisted of between 8 and 20 myosin molecules and were relatively stable at low temperatures (T<20 ° C) in dilute (C<5 g / L) solutions containing 0.5 M KCl in the pH range 6.0–8.0. At higher concentrations precipitation or gelation was observed. Heat-induced aggregation at low concentrations was studied using turbidimetry and light scattering. In most cases the aggregation stagnated at longer heating times, but in some cases the aggregation continued until it led to precipitation of large flocs. Cooling led to further growth of the aggregates, which was, however, reversed upon heating.
The structure of the aggregates was determined after cooling and dilution using static and dynamic light scattering. Self-similar aggregates were observed, characterized by a fractal dimension of 2.2. The size of the aggregates formed after extensive heating increased with increasing temperature (30–70 ° C), decreasing pH (8.0–6.0) and increasing protein concentration (0.4–3 g / L), but the structure of large aggregates was independent of the conditions.
The production by enzymatic treatment of fish protein hydrolysates (FPH) is a promising route to add value to fisheries proteinic co-products (fish frames, heads etc.). Indeed, FPH possess good nutritional properties and biological activities for food and feed uses. Pressure-driven membrane separations such as ultrafiltration (UF) and nanofiltration (NF) can be used after the hydrolysis to increase the specific activities of the FPH. This paper discusses the impact of a two-step UF / NF process producing four different fractions on two industrial FPH with different hydrolysis degrees. Fractionation is carried out in “realistic” conditions for an industrial process, on highly concentrated FPH solutions (about 100 g of dry matter / L) at a high volume reduction factor. For each step, UF or NF, the variation of the permeation flux in the course of the fractionation is discussed according to the FPH hydrolysis degree and the membranes cut-offs. The values of performance indicators defined in terms of nitrogen content are also examined, including the concentration factor (CF), the relative recovery in the retentate (ηR) and the mean and final retention factors (RFm and RFf). Computed values of these indicators are validated through the setting of volume and mass balances around each step. The impact of fractionation on the FPH peptidic population is shown. Peptidic populations are described in terms of chromatographic profiles (SEC – FPLC). The UF fractionation produces a permeate enriched with respect to the FPH smaller than a molecular weight of about 600–750 Dalton, and a retentate enriched in large peptides (above the same MW). A similar behavior is found for the NF fractionation. Comparing the impact of the UF fractionation on the two hydrolysates allows to conclude that the membrane cut-off is well-suited when comprised between the MWs of the biggest and the most abundant peptides in the FPH.
The protein requirements of Atlantic halibut (Hippoglossus hippoglossus L) were tested in two trials for fish with initial size of 564 g and 973 g. The fish were fed near isocaloric diets with crude protein in dry matter (CP) between 35% and 53%. There was no significant effect of CP on weight development or SGR, daily feed intake or protein efficiency ratio in either trial. However, CP significantly affected the feed conversion (FCR) of the smaller fish with FCR increasing at lower CP. The CP did not affect the final protein or lipid content of the fish. The results of the study suggest that the minimum CP for maximum growth is 41% and 35% for 560 g and 970 g halibut respectively.
Moritella viscosa causes winter ulcer disease in salmonids. The aim of the present work was to isolate and partially characterize an extracellular peptidase from M. viscosa, and to study its role in virulence. The peptidase, termed MvP1, was a 38-kDa metallopeptidase produced in late exponential growth. The optimum temperature for MvP1 was 40 ° C, but the enzyme was active over a wide range of temperatures. MvP1 was non-lethal to salmon at concentrations up to 0.22 μg / g fish, but extracellular products were lethal to salmon. MvP1 degraded casein, gelatin and collagen from lumpfish skin. It caused considerable tissue necrosis and hemorrhages at the site of injection, and affected cell – cell adhesions in EPC and BF-2 cell lines, but was not highly cytotoxic. The peptidase partially degraded fish IgM heavy chain but was non-hemolytic. The mvp1 gene was sequenced and encoded a 734-aa polypeptide containing a signal sequence, an N-terminal propeptide, a mature peptidase domain and a C-terminal propeptide. The MvP1 propeptide undergoes both N-terminal and C-terminal processing and different C-terminal processing results in the formation of several active isoforms of the mature peptidase. The catalytic domain showed highest sequence similarity with several vibriolysins (EC 3.4.24.25) originating from Pseudoalteromonas strains, showing up to 80% aa identity. The results indicate that MvP1 is a previously unknown vibriolysin that might affect M. viscosa virulence by aiding in the invasion and dissemination of the bacterium in its host, by causing tissue destruction.
Strains PRI 2268 and PRI 3838T were isolated from two separate hot springs in the Torfajokull geothermal area of South Iceland. The cells were non-motile rods, approximately 0.3 μm in width and 1.5–2.5 μm in length. Electron microscopy revealed a Gram-negative cell-wall structure. The strains grew at 45–79 ° C (optimum, 65 ° C) and pH 5.5–10.5 (optimum, pH 6.0–7.0). 16S rRNA gene sequence analysis indicated that they formed a separate branch within the genus Thermus with 'Thermus kawarayensis'KW11 as their closest cultured relative (96.5 % similarity). The gene sequence similarities of both new isolates to Thermus aquaticus YT-1T and Thermus igniterrae RF-4T were 96.1 % and 95.5 %, respectively. DNA – DNA relatedness between strain PRI 3838T and 'T. kawarayensis'was 46.1 %. The DNA G + C content of strain PRI 3838T was 69.0 mol%. The predominant menaquinones, pigmentation, fatty acid profiles and phospholipid profiles of the novel strains were similar to those of other members of the genus Thermus. However, the new strains could be differentiated from the type strains of all other species of the genus Thermus by their lack of catalase activity and their utilization of only a few carbon sources. Furthermore, the novel strains exhibited mixotrophic growth with sulfur oxidation. On the basis of 16S rRNA gene sequence comparisons, DNA – DNA hybridization and physiological and biochemical characteristics, the new isolates represent a novel species. Since the species appears to be ubiquitous in Icelandic hot springs, the name Thermus islandicus sp. nov. is proposed. The type strain is PRI 3838T (= DSM 21543T= ATCC BAA-1677T).