Since the 1950s, massive volumes of per- and polyfluoroalkyl substances (PFAS) (called "forever chemicals") have been released into the environment, contaminating soil, surface water, and groundwater sources. PFAS are regularly exposed to humans, animals, and the environment through food, water, consumer products, and waste streams from PFAS-manufacturing businesses. Recent pharmacological research has identified the direct and indirect pathways that connect the human gut microbiome to xenobiotic biotransformation. Though environmental contaminants are an important component of xenobiotics and exhibit overlapping biotransformation routes with gut microbial metabolites, the probable interaction between gut microbiome and environmental contaminant biotransformation remains unknown.

The purpose of this research was to determine the influence of oxygen respiration on the biotransformation of alternative electron acceptors (e.g., nitrate and sulfate) that underpins the simultaneous removal of ammonium and sulfate in a single aerated sequencing batch reactor. In the feast condition, complete nitrification was obtained. Antibiotic combinations in the environment cause the emergence of bacterial strains resistant to various antibiotics. Oxidases are versatile enzymes that can biodegrade antibiotics. In Pichia pastoris, several laccases (LACs), manganese peroxidases (MNPs), and versatile peroxidase (VP) were recreated.