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Thaw rigor in Atlantic salmon (Salmo salar) fillets, as affected by thawing rate and frozen storage time
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High diversity in the regulatory region of Shiga toxin encoding bacteriophages
Get PDFBackground: Enterohemorrhagic Escherichia coli (EHEC) is an emerging health challenge worldwide and outbreaks caused by this pathogen poses a serious public health concern. Shiga toxin (Stx) is the major virulence factor of EHEC, and the stx genes are carried by temperate bacteriophages (Stx phages). The switch between lysogenic and lytic life cycle of the phage, which is crucial for Stx production and for severity of the disease, is regulated by the CI repressor which maintain latency by preventing transcription of the replication proteins. Three EHEC phage replication units (Eru1-3) in addition to the classical lambdoid replication region have been described previously, and Stx phages carrying the Eru1 replication region were associated with highly virulent EHEC strains. Results: In this study, we have classified the Eru replication region of 419 Stx phages. In addition to the lambdoid replication region and three already described Erus, ten novel Erus (Eru4 to Eru13) were detected. The lambdoid type, Eru1, Eru4 and Eru7 are widely distributed in Western Europe. Notably, EHEC strains involved in severe outbreaks in England and Norway carry Stx phages with Eru1, Eru2, Eru5 and Eru7 replication regions. Phylogenetic analysis of CI repressors from Stx phages revealed eight major clades that largely separate according to Eru type. Conclusion: The classification of replication regions and CI proteins of Stx phages provides an important platform for further studies aimed to assess how characteristics of the replication region influence the regulation of phage life cycle and, consequently, the virulence potential of the host EHEC strain.High diversity in the regulatory region of Shiga toxin encoding bacteriophagespublishedVersio
Evaluation of a recirculating aquaculture system research facility designed to address current knowledge needs in Atlantic salmon production
Get PDFA better understanding of recirculating aquaculture systems (RAS) biosecurity is crucial for a sustainable and ethical production of Atlantic salmon smolt and post-smolt in these systems. This study described and evaluated the performance of a RAS facility for fish infection research with Atlantic salmon as the main animal model. Fish body weight, length, water quality and system metrics from five independent experimental trials conducted between September 2020 and July 2021, were used to analyse the variation within and between treatments. Statistical power analysis was performed to determine the minimum number of fish required to use. The fish parameters variability showed that the inter-class correlation coefficient was on average low (0.1) and that the variation within tanks was larger than the variation between tanks. The realized power of the five-experiment average was 47 % for length and 59 % for weight. Assuming the maximum available number of tanks to achieve a power of 80 %, a medium to large treatment effect (0.5 - 0.8) and an inter-class correlation coefficient of 0, a minimum of 15 fish sampled per tank is required for the current study conditions. Water quality and system management metrics variation among the five experimental trials was higher compared to variation within the five experimental trials. Moreover, the variation of the water quality parameters controlled by sensors was relatively low, whereas parameters depending on biofilter maturation level and performance presented a very high variation. Water exchange rate dependent quality parameters showed a similar variation value, i.e., nitrate and water turbidity. The established baseline for variability and performance presents an important reference for the design and realization of future experiments in this RAS facility. It is foreseen that the current research facility will develop new knowledge to improve the RAS biosecurity in the Atlantic salmon aquaculture industry.Evaluation of a recirculating aquaculture system research facility designed to address current knowledge needs in Atlantic salmon productionpublishedVersio
CtrlAQUA - Annual Report 2021 - Centre for Closed-Containment Aquaculture
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Applications of hyperspectral imaging for documenting smoltification status and welfare in Atlantic salmon
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