The growing practice of wastewater reuse poses a significant risk to further 13 dissemination of antibiotic resistance due to the abundance of antibiotic resistance 14 bacteria (ARB) and antibiotic resistance genes (ARGs) in wastewater effluents. Anaerobic 15 membrane bioreactors (AnMBRs) are an emerging wastewater treatment technology 16 capable of reducing the total ARGs and ARB load discharged to receiving environments 17 compared to conventional aerobic treatment processes. While size exclusion is effective 18 at retaining ARB and its associated intracellular ARGs, the abundance and fate of 19 extracellular ARGs in an AnMBR effluent have not been examined. This study elucidates 20 the effect of combined antibiotics loading (ampicillin, erythromycin, and 21 sulfamethoxazole) on the abundance of intracellular and extracellular ARGs in an AnMBR 22 chemical oxygen demand (sCOD), total chemical oxygen demand (tCOD), volatile fatty 128 acids (VFAs), and mixed liquor and volatile suspended solids (MLSS/MLVSS). Biogas 129 production was monitored by an in-line gas flowmeter and assessed for methane content 130 by gas chromatography with flame ionization detection (GC-FID). Steady AnMBR