抄録
This study aimed to elucidate antibiotic-resistant bacterial communities in the lake sediments of Lake Kitaura, Japan using culture-based and non-culture methods. Based on bacterial 16S rRNA amplicon sequencing using DNA extracted from the lake sediments, PICRUSt2 predictive metagenomic analysis suggested an increased representation of taxa whose reference genomes contain genes associated with tetracycline (TC) resistance. The rate of TC-resistant bacteria increased in river water downstream of the Hokota River, and TC-resistant bacteria appeared in lake sediments upstream of the lake based on the culture-dependent assay. PCR amplification revealed TC resistance genes (tetA, B, M, O, and W) in the river water downstream of the river. However, only the tetW amplicon was detected in the water above the lake sediment and in the lake sediments in the upper reaches. 18 TC-resistant bacterial strains obtained from river water and lake sediments suggested that TC-resistant bacterial communities diversified in the lower reaches of the river. Additionally, we identified TC-resistant bacterial strains that amplified tetAB and tetM by PCR, respectively. Furthermore, tetW-based meta-amplicon sequence analysis showed that infectious and intestinal bacteria from humans and animals inflowed from the lower reaches of the river into the lake. To the best of our knowledge, this study is the first to report that TC-resistant bacteria reach the upper reaches of the lake sediments of Lake Kitaura via the Hokota River.
