Antibiotic and Heavy Metal Resistant Bacteria Isolated from Aegean Sea Water and Sediment in Güllük Bay, Turkey : Quantifying the resistance of identified bacteria species with potential for environmental remediation applications

Heavy metal and antibiotic-resistant bacteria have potential for environmental bioremediation applications. Resistant bacteria were investigated in sediment and seawater samples taken from the Aegean Sea, Turkey, between 2011 and 2013. Bioindicator bacteria in seawater samples were tested using the membrane filtration technique. The spread plate technique and VITEK® 2 Compact 30 micro identification system were used for heterotrophic aerobic bacteria in the samples. The minimum inhibition concentration method was used for heavy metal-resistant bacteria. Antibiotic-resistant bacteria were tested using the disk diffusion method. All bacteria isolated from sediment samples showed 100% resistance to rifampicin, sulfonamide, tetracycline and ampicillin. 98% of isolates were resistant against nitrofurantoin and oxytetracycline. Higher antibiotic and heavy metal resistance was recorded in bacteria isolated from sediment than seawater samples. The highest levels of bacterial metal resistance were recorded against copper (58.3%), zinc (33.8%), lead (32.1%), chromium (31%) and iron (25.2%). The results show that antibiotic and heavy metal resistance in bacteria from sediment and seawater can be observed as responses to environmental influences including pollution in marine areas.