Determining Indicator Antibiotic Resistance Genes for Effectively Monitoring Dissemination of Antibiotic Resistance Genes in Orchard Soils, South Korea

Abstract

The proliferation of antibiotic resistance bacteria and genes has become major concerns in public health. It has been known that agricultural pesticides were heavily applied to orchards in South Korea. Thus, in this study, we investigated to profile antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) using high-throughput qPCR in orchard soils in South Korea. A total of 297 ARGs and 52 MGEs were detected in the orchard samples, which were significantly higher than those in the control samples. Linear discriminant analysis effect size (LEfSe) analyses identified seven discriminative ARGs in the orchard samples, including aac3-Via, tetL, aadE, qacH_351, sul1, strB, and aac(3)-Xa, which accounted for 39.4% of the total ARGs abundance. Network analysis revealed significant relationships among ARGs, MGEs, and bacterial genera, highlighting the correlation between core ARGs and MGEs. This indicates the role of MGEs in facilitating the horizontal gene transfer (HGT) of ARGs in orchard soils. Furthermore, MGEs and bacterial phyla, such as Actinomycetota, likely contributed to the variation in ARGs. Variance partitioning analysis (VPA) further revealed that MGEs accounted for 34.39% of the variation in ARG profiles, emphasizing their crucial role in the dissemination of ARGs. These findings show the significant impact of agricultural practices on the proliferation of ARGs in the orchard soils in South Korea and emphasize the role of MGEs as key drivers of ARGs dissemination. This study contributes to a better understanding of antibiotic resistance in orchard environments where agricultural pesticides were heavily - applied.