Distribution of antibiotic-resistant bacteria in the Abyssal sea and the strengthening of resistance traits by exposure to microplastics

摘要

Although residues from the antibiotics found in marine products were originallyexamined as a pressing problem facing marine life, marine bacteria’s resistance toantibiotics has recently come to the fore as a central environmental issue. This studywas conducted to examine antibiotic resistance levels among different marine samplesand to show the connection between marine bacteria’s resistance to antibiotics andtheir exposure to microplastics. Marine bacteria were collected from coastal seawater,abyssal seawater, and coastal sand, and intestinal bacteria were collected from deepseafish, coastal fish, shellfish, and rotten fish; each of these samples of bacteria wastested for resistance to four types of antibiotics (meropenem, streptomycin, penicillin,and vancomycin). Among the types of bacteria collected from the coastal sand, 87.1%to 100% showed resistance to one or more of the selected antibiotics, and among thetypes of bacteria collected from the coastal waters, 84.6% to 100% showed antibioticresistance. In addition, when the distribution of resistant bacteria was observed inintestinal bacteria collected from coastal and abyssal fish, the intestinal bacteria ofabyssal fish had lower rates of resistance to antibiotics than that of coastal fish;moreover, 100% of versatile resistant bacteria (which showed resistance to more thanthree types of antibiotics) found in the intestines of coastal fish were resistant toantibiotics while, among abyssal fish, only 92% showed resistance. Among theintestinal bacteria found in shellfish and decomposing fish except for one type ofsensitive bacteria, all types of bacteria were resistant to vancomycin and meropenem.Finally, as a result of culturing antibiotic-resistant bacteria with microplastics, 11 outof 12 types of bacteria developed antibiotic resistance, showing that exposure tomicroplastics can cause antibiotic resistance. Based on these results, it can beconcluded that microplastics contribute to the development of antibiotic resistanceamong marine bacteria.