Changes in antibiotic resistance genotypes and phenotypes after two typical sewage disposal processes

Area of Science:

• Environmental microbiology
• Public health
• Wastewater treatment technologies

Background:

• Antibiotic resistance genes (ARGs) in wastewater treatment plants (WWTPs) are a global concern.
• Understanding ARG and resistant bacteria distribution in different WWTP processes is limited.

Purpose of the Study:

• To quantitatively study the abundance and fate of antibiotic resistance genotypes and phenotypes.
• To compare ARG and resistant bacteria removal in biological aerated filter (BAF) and anaerobic-oxic (A/O) systems.

Main Methods:

• Quantitative analysis of antibiotic resistance genotypes and phenotypes.
• Comparison of BAF and A/O wastewater treatment processes.
• Investigation of bacterial community evolution and its relation to tetracycline resistance.

Main Results:

• Average removal rate of total ARGs exceeded 90%.
• ARG abundance increased in A/O units but decreased in BAF units.
• BAF systems showed higher removal rates for resistant bacteria than A/O systems.
• Tetracycline resistance in bacteria correlated with bacterial community changes.

Conclusions:

• While ARGs are largely removed, WWTPs can be hotspots for resistance.
• BAF systems are more effective than A/O systems for removing resistant bacteria.
• Mitigation strategies should prioritize removing bacterial hosts to reduce ARG environmental release.