Antibiotic resistance genes (ARGs), a potential threat to the health of humans and animals, have been widely detected in various environments. However, not much information about ARGs in freshwater lakes have been recorded. In this study, we investigated the occurrence of 17 kinds of ARGs and three types of integronase genes in Taihu Lake (China), an important drinking water source for local residents. Fecal coliforms were also isolated from the water and sediments for antimicrobial susceptibility tests and related ARGs detection. Results showed that tetracycline resistance gene tetC, sulfanilamide resistance genes sul1 and sul2, and class 1 integronase gene int1 were present in all water and sediment samples. TetG was present in all water samples but was mainly distributed in sediment samples from the northern region of Taihu Lake. β-Lactam resistance gene bla OXA-1 was present in all water samples but was absent in the sediment samples. TetM and tetO were found present in water and sediment samples from the western area of the lake. Remarkably, 95% of isolated fecal coliforms were resistant to trimethoprim and multi-drug resistant isolates were also observed. Sul1 and tetC genes were found to be carried by isolates resistant to corresponding antibiotics. This study provided baseline information about the occurrence of ARGs and integronase genes in Taihu Lake and the results may extend our knowledge about antibiotic resistance of microbial communities in the lake.

Antibiotic resistance genes (ARGs), a potential threat to the health of humans and animals, have been widely detected in various environments. However, not much information about ARGs in freshwater lakes have been recorded. In this study, we investigated the occurrence of 17 kinds of ARGs and three types of integronase genes in Taihu Lake (China), an important drinking water source for local residents. Fecal coliforms were also isolated from the water and sediments for antimicrobial susceptibility tests and related ARGs detection. Results showed that tetracycline resistance gene tetC, sulfanilamide resistance genes sul1 and sul2, and class 1 integronase gene int1 were present in all water and sediment samples. TetG was present in all water samples but was mainly distributed in sediment samples from the northern region of Taihu Lake. β-Lactam resistance gene blaOXA-1 was present in all water samples but was absent in the sediment samples. TetM and tetO were found present in water and sediment samples from the western area of the lake. Remarkably, 95% of isolated fecal coliforms were resistant to trimethoprim and multi-drug resistant isolates were also observed. Sul1 and tetC genes were found to be carried by isolates resistant to corresponding antibiotics. This study provided baseline information about the occurrence of ARGs and integronase genes in Taihu Lake and the results may extend our knowledge about antibiotic resistance of microbial communities in the lake.