Antibiotic Resistance and Prevalence of Class 1 and 2 Integrons in Escherichia coli Isolated from Two Wastewater Treatment Plants, and Their Receiving Waters (Gulf of Gdansk, Baltic Sea, Poland)

Abstract

Abstract:In order to comprehensively investigate tetracycline resistance in activated sludge of sewage treatment plants, 454 pyrosequencing and Illumina high-throughput sequencing were used to detect potential tetracycline resistant bacteria (TRB) and antibiotic resistance genes (ARGs) in sludge cultured with different concentrations of tetracycline. Pyrosequencing of 16S rRNA gene revealed that tetracycline treatment greatly affected the bacterial community structure of the sludge. Nine genera consisting of Sulfuritalea, Armatimonas, Prosthecobacter, Hyphomicrobium, Azonexus, Longilinea, Paracoccus, Novosphingobium and Rhodobacter were identified as potential TRB in the sludge. Results of qPCR, molecular cloning and metagenomic analysis consistently indicated that tetracycline treatment could increase both the abundance and diversity of the tet genes, but decreased the occurrence and diversity of non-tetracycline ARG, especially sulfonamide resistance gene sul2. Cluster analysis showed that tetracycline treatment at subinhibitory concentrations (5 mg/L) was found to pose greater effects on the bacterial community composition, which may be responsible for the variations of the ARGs abundance. This study indicated that joint use of 454 pyrosequencing and Illumina high-throughput sequencing can be effectively used to explore ARB and ARGs in the environment, and future studies should include an in-depth investigation of the relationship between microbial community, ARGs and antibiotics in sewage treatment plant (STP) sludge. OPEN ACCESSInt. J. Mol. Sci. 2014, 15 10084

Minimal selective concentrations of tetracycline in complex aquatic bacterial biofilms

“…Tetracycline concentrations of ≤1 μg/L selected for both tetA and tetG genes. Selection of tetA and tetG has previously been reported when exposing activated sludge bacteria, diluted in filtrated sewage influent, to very high concentrations of TC (5 and 20 mg/L) for six days (Huang et al, 2014). This indicates some degree of robustness of tetA and tetG as markers for a selection pressure from tetracycline.…”

“…This indicates some degree of robustness of tetA and tetG as markers for a selection pressure from tetracycline. However, in the study by Huang et al (2014), no effect on either gene was seen at 1 mg/L, the lowest concentration tested. It is unclear if this is a reflection of limited bioavailability of TC, use of an already established community in the assay, and/or fewer bacterial generations studied.…”

Fate of antibiotic resistance genes and antibiotic‐resistant bacteria in water resource recovery facilities

“…They found that 11 tet genes were present in the sludge, including tetA , tetB , tetC , tetG , tetK , and tetP(A) encoding tetracycline efflux proteins; tetM , tetO , tetS , and tetW encoding ribosomal protection proteins; and tetX encoding enzymatic modification protein. The amount of all of the tet genes increased, while sulII was decreased (Huang et al., ). Similarly, in a bench‐scale activated sludge process with 500 μg/L tetracycline influent, an increase in the proportion of tetA and tetB as well as both tetracycline‐intermediate‐resistant and tetracycline‐resistant heterotrophic bacteria occurred (Yu, Liu, & Li, ).…”

“…In order to observe the ability of activated sludge processes to remove ARGs and ARB, some researchers simulated mechanisms in laboratory‐scale reactors. Huang, Tang, Zhang, Xu, and Ren () sampled activated sludge from a water resource recovery facility in Nanjing, China, and detected the abundance of tetracycline and sulfonamide resistance genes. They found that 11 tet genes were present in the sludge, including tetA , tetB , tetC , tetG , tetK , and tetP(A) encoding tetracycline efflux proteins; tetM , tetO , tetS , and tetW encoding ribosomal protection proteins; and tetX encoding enzymatic modification protein.…”

“…Interestingly, when tetracycline resistance genes exist in activated sludge together with other ARGs such as sulII , the occurrence and diversity of nontetracycline ARGs decreased (Huang et al., ). They found that the considerable decrease in the abundance of sulII (from 83.49% to 14.76%) might be attributed to the domination of tetracycline in the sludge, owing to the higher abundance in the sludge without tetracycline stress than with tetracycline stress.…”