Antibiotic Resistance and Phylogeny of Bacterial Isolates with Biogeochemical Analysis from Sediments of Eastern Mediterranean Sea

Abstract

Ilknur Tuncer and Nihayet Bizsel

Background: Bacteria in marine environments show different diversity and resistance patterns. In this study, the phylogeny and antibiotic susceptibility levels of bacterial strains isolated from sediments of Eastern Mediterranean Sea (0–1235 m depths) were analyzed in association with geochemical parameters of sediments.

Methods: Bacterial isolation was performed and totally 185 isolate whose 16S rRNA gene sequences were deposited into NCBI Gen Bank were assayed with disk diffusion method using eleven antibiotics. Statistical comparison was performed for susceptibility levels of strains and geochemical parameters of stations as grain size and carbon, nitrogen, phosphorus contents of sediment samples.

Results and Conclusion: The highest resistance was mostly to amikacin and ceftazidime. While the Bacillus strains with the highest diversity had the highest resistance, the genera Planococcus, Marinobacter, Psychrobacter and Vibrio were susceptible to all antibiotics and even the genera Halobacillus, Fictibacillus, Lysinibacillus, Salinimonas, Photobacterium, Planococcus, Psychrobacter and Vibrio had no intermediate level. The geochemical contents of the sediments and susceptibility levels of the bacterial isolates were not statistically correlated but there was positive correlation between grain size and resistance. Due to the influence of terrestrial and anthropogenic factors, the shallowest stations had the highest resistance and were separated from deep-basins in correlation analysis.

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