Fungus reduces tetracycline-resistant genes in manure treatment by predation of bacteria

New strategies to remove antibiotic resistance genes (ARGs), one of the most pressing threats to public health, are urgently needed. This study showed that the fungus Phanerochaete chrysosporium seeded to a composting reactor (CR) could remarkably reduce tetracycline-resistant genes (TRGs). The reduction efficiencies for the five main TRGs (i.e., tetW, tetO, tetM, tetPA, and tet(32)) increased by 8 to 100 folds compared with the control without P. chrysosporium, and this could be attributed to the decrease in the quantity of bacteria. Enumeration based on green fluorescence protein labeling further showed that P. chrysosporium became dominant in the CR. Meanwhile, the bacteria in the CR invaded the fungal cells via the cell wall defect of chlamydospore or active invasion. Most of the invasive bacteria trapped inside the fungus could not survive, resulting in bacterial death and the degradation of their TRGs by the fungal nucleases. As such, the predation of tetracycline-resistant bacteria by P. chrysosporium was mainly responsible for the enhanced removal of TRGs in the swine manure treatment. This study offers new insights into the microbial control of ARGs.

A highly selective and sensitive electrochemical sensor for tetracycline resistant genes detection based on the non-covalent interaction of graphene oxide and nucleobase

Antibiotic resistance genes (ARGs) are causing worldwide environmental problems, however, the traditional analytical methods and test equipment for them are time-consuming and expensive. The electrochemical sensor using the non-covalent bond between graphene oxide (GO) and single-stranded tet (ss-tet) was established for specific tetracycline resistance genes (tet, composed of ss-tet and complementary ss-tet (ss-tet') in water) detection, which preparation time was only 35 min and far less than most reported sensors based on covalent bond. As the result of the detection for tet, the developed sensor not only had the low detection limit of 50.0 pM (8.1 × 102 copies·mL-1), the short detection time within 42 min, but also had satisfactory stability, excellent reproducibility, and highly selectivity (RSD < 4.43 %). Besides, it also had acceptable accuracy comparing to the real-time quantitative polymerase chain reaction (RT-qPCR) and PCR array in tet detection. Noticeably, it also had been successfully applied to tetA detection in different water samples. In brief, the prepared non-covalent bond sensor is simple, rapid, and suitable for highly selective and sensitive detection of the ARGs in actual water.

Trueperella pyogenes isolated from dairy cows with endometritis in Inner Mongolia, China: Tetracycline susceptibility and tetracycline-resistance gene distribution

Trueperella pyogenes plays a crucial role in endometritis pathogenesis and is also associated with many infections, including metritis, mastitis, arthritis and liver abscessation, in many domestic animals. In this study, we investigated the prevalence of tetracycline resistance in T. pyogenes isolated from dairy cows with endometritis in Inner Mongolia, China, and we assessed tetracycline-resistance gene distribution among the isolates. Our results indicated that 68.7% and 62.5% of the isolates were resistant to tetracycline and doxycycline, respectively, and the rate of resistance to metacycline was 18.8%. The tetracycline resistance gene tetK was present in all isolates (n = 32), whereas the tetM gene was identified in 12.5% and 9.4% of the isolates, in the chromosome and plasmid, respectively. Strains carrying tetW were also common in the chromosome and plasmid, with abundances of 53.1% and 46.9%, respectively. However, tetO and otrA were absent in all isolates. The resistance phenotype analysis indicated that 6.3% of strains were susceptible to all tetracyclines, while 3.1% showed resistance to all tetracyclines.