[Impact of Tetracycline Antibiotic on the Transcriptional Expression of Tetracycline Resistance Genes in ].

The tetracycline (TC) antibiotic has been widely found in different environmental matrices. The tetracycline resistant bacterium (TRB) of was screened and purified from activated sludge, and was then used to study the impact of TC stress on the gene abundances and expression levels of TC resistance genes (TC-ARGs), including , , and , which were respectively quantified by quantitative PCR and reverse transcriptional PCR. Correlations between the TC concentration and gene abundances of TC-ARGs and their expression levels were discussed. The results showed that TC stress had an inhibiting effect on the growth of during the entire culture cycle (24 h) and that the growth rate of the bacterial concentration decreased with increasing TC concentration. However, less impact on the gene abundance of TC-ARGs was found. TC stress could promote the expression of TC-ARGs in , and the expression levels of , , and genes first increased and then decreased. The correlation results indicated that no significant correlation was observed between the TC concentration and gene abundances of TC-ARGs and their expression levels. Nevertheless, the gene abundances of and were significantly correlated with their expression levels, thus indicating that they can be used to evaluate and assess expression levels to a certain extent.