Molecular analysis of skin bacterial assemblages from codfish and pollock after dry-salted fish production.

Dry-salted codfish and pollock are commercially important food products with a relatively long shelf life. To date, bacterial assemblages present in these products that are relevant for food safety have been monitored using only classical molecular and/or cultivation methods. The present study employed a rapid and accurate identification method involving PCR with denaturing gradient gel electrophoresis and pyrosequencing to characterize the bacterial assemblages in the skin of three closely related fishes: Gadus morhua, Gadus macrocephalus, and Theragra chalcogramma. This methodology can be crucial for timely identification of food spoilage, hazard analysis, and monitoring of critical control points during food production. Although all specimens were processed in the same factory, there were significant compositional differences in their skin bacterial communities. In general, the bacterial community was dominated by gram-negative species of the Gammaproteobacteria. Pyrosequencing yielded 90, 69, and 245 operational taxonomic units associated with G. morhua, G. macrocephalus, and T. chalcogramma, respectively. The most dominant operational taxonomic units were assigned in order to Pseudomonas sp., Serratia marcescens, Salinisphaera sp., and Psychrobacter pulmonis. Spoilage and pathogenic bacterial groups were detected in all the studied salted gadoid samples.

Richness and composition of sediment bacterial assemblages in an Atlantic port environment.

In the present study, we assessed the bacterial richness and composition of sediment samples collected in and around the port of Aveiro, on the Atlantic coast of mainland Portugal. Sediment samples were collected in five locations: two within the port harbor, two in port areas along a channel adjacent to the harbor and one in a relatively undisturbed reference location. These areas were characterized as under high, medium and no port activity, respectively. In-depth, barcoded-pyrosequencing analysis indicated that port activity affects the composition and abundance of bacterial communities colonizing surface sediments. Sampling sites under the influence of port activities (channel and harbor) were associated with higher relative abundances of Desulfobacterales and a marked decline in the abundance of Flavobacteriia. In addition, there was a pronounced prevalence of operational taxonomic units (OTUs) in the port area that were closely related to hydrocarbon-degrading bacteria (Desulfococcus spp.), antifouling paint (bacterium strain WH6-7) and copper rich sediments (bacterium strain CanalPD16A). Here we provide evidence that specific phylotypes detected have the potential to be used as biomarkers and should be evaluated in future studies as proxies for sediment disturbance associated with port activity.