engleski

Metal pollution and bacterial diversity in the surface sediments in the north Adriatic Sea

The marine environment is often representing a collection site for contaminants produced by industrial processes, oil exploration and active harbours and ship transport. All of these activities can generate heavy metal contamination. In addition to heavy metals, marine sediments and bays can be influenced by effluents of wastewater treatment plants (WWTPs), a hotspot of antibiotic resistance selection and a direct source for their spread into the environment. The present study was conducted in the bay of Pula, a semi enclosed costal ecosystem experiencing very strong contamination from multiple sources. In order to detect these influences in depth microbiological and chemical characterizations of surface sediments were performed. Based on the measured heavy metal concentrations, the fifteen investigated sites clustered into three groups, with one outgroup site. Bacterial communities in the sediment samples were mainly dominated by Gammaproteobacteria and Deltaproteobacteria, except two sites close to the discharge of a WWTP, which were dominated by Epsilonproteobacteria. In all samples, metal resistance genes (arsB and czcA) were detectable by qPCR. We found a positive correlation between the relative abundance of the Ectothiorhodospiraceaeand the abundance of arsB gene copy numbers, and between Rhodospirillaceae and Sva1033 clades and the czcA gene copy numbers. Furthermore, antibiotic resistance genes against erythromycin (ermB) and β-lactams (blaTEM) were detectable in various samples throughout the bay.

bacteria ; surface sediments ; metal resistance gene

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