"Under pressure" : interaction between pharmaceuticals and river bacteria

Abstract: Pharmaceuticals are often entering the environment without being completely decomposed. Once released in the environment they continue to carry on their main function but instead targeting the inhabitants of the aquatic ecosystem. Our interest was drawn towards the bacteria, that are often present in the environment in the form of biofilms. Despite their small size, they are carrying on important functions for the ecosystem. Any disruption in their work can potentially result a disturbance in the whole ecosystem. Thus, knowing the possible effect of the pharmaceuticals on bacterial biofilms can give us more understanding about the mechanisms that lie beneath pharmaceutical pollution.Natural degradation processes like photolysis, hydrolysis, and biodegradation can reduce pollutant concentrations. Bacterial biofilms, common in aquatic ecosystems, play a crucial role in pharmaceutical degradation process. The extracellular polymeric substances (EPS) produced by biofilms enhance their tolerance to environmental stressors.This study focuses on bacterial biofilms chronically exposed to low levels of pharmaceuticals remaining in the treated waste water released from a STP into the Knivsta River, Sweden. Using the sequencing we mapped the species that inhabited the sampling location. Model biofilm consortia were constructed and characterized using various analysis techniques. Experiments investigated bacterial motility, biofilm formation, and interactions between isolates. The bacterial isolates exhibited diverse motility patterns. Cross- cultivation assays indicated coexistence without negative interactions among isolates. Chemical analysis using ATR-FTIR spectroscopy and cryo-XPS revealed differences in macromolecular composition among isolates.The impact of pharmaceuticals, such as Trimethoprim and Diclofenac, on bacterial growth was studied.The findings contribute to understanding the complex interactions between pharmaceuticals and bacterial biofilms, crucial for assessing environmental risks and designing possible wastewater treatment strategies.