Cell Adaptations of Rhodococci to Pharmaceutical Pollutants

Against the background of atense environmental situation, the risk of drug pollution in the natural environment is steadily increasing. Pharmaceuticals entering open ecosystems can cause toxic effects in wildlife from molecular to population levels. The aim of this research was to examine the impact of pharmaceutical pollutants on rhodococci, which are typical representatives of soil actinobacteria and active biodegraders of these compounds. The pharmaceutical products used in this research werediclofenac sodium and ibuprofen, which are non-steroidal anti-inflammatory drugs (NSAIDs) that are widely used and frequently found in the environment. The most common cell adaptations of rhodococci to the effects of NSAIDs were changes in zeta potential, catalase activity, morphometric parameters and degree of hydrophobicity; elevated contents of total cellular lipids; and the formation of cell conglomerates. The findings demonstrated the adaptation mechanisms of rhodococci and their increased resistance to the toxic effects of the pharmaceutical pollutants. Keywords: pharmaceutical pollutants, NSAIDs, diclofenac, ibuprofen, cell responses, Rhodococcus

Fate of Pharmaceuticals in a Submerged Membrane Bioreactor Treating Hospital Wastewater

The fate of 12 pharmaceutical pollutants was investigated to understand their removal mechanism during hospital wastewater (HWW) treatment in submerged membrane bioreactor (SMBR). High concentrations of anti-depressant (venlafaxine and desvenlafaxine), analgesic (ibuprofen and hydroxy-ibuprofen), and caffeine were detected in the HWW during the entire study period. The SMBR showed high removal >70% of antibiotics (sulfamethoxazole and clarithromycin), beta-blocker (acebutolol), hormone (estrone), and caffeine via biodegradation. The partial degradation of diclofenac, venlafaxine, and desvenlafaxine in SMBR indicates the growth promoter or agent requirement, which could facilitate the metabolism and co-metabolism of these pharmaceuticals by microorganisms. The study demonstrated that the major removal mechanism of pharmaceuticals in SMBR at optimized treatment conditions was biodegradation for the majority of examined pharmaceuticals. The assessment of SMBR performance at the low temperature of 15 and 10°C resulted in the drop of biodegradation efficiency of SMBR, affecting overall pharmaceuticals removal.

Microbial Electrochemical Fluidized Bed Reactor: A Promising Solution for Removing Pollutants From Pharmaceutical Industrial Wastewater

The capacity of electroactive bacteria to exchange electrons with electroconductive materials has been explored during the last two decades as part of a new field called electromicrobiology. Such microbial metabolism has been validated to enhance the bioremediation of wastewater pollutants. In contrast with standard materials like rods, plates, or felts made of graphite, we have explored the use of an alternative strategy using a fluid-like electrode as part of a microbial electrochemical fluidized bed reactor (ME-FBR). After verifying the low adsorption capacity of the pharmaceutical pollutants on the fluid-bed electrode [7.92 ± 0.05% carbamazepine (CBZ) and 9.42 ± 0.09% sulfamethoxazole (SMX)], our system showed a remarkable capacity to outperform classical solutions for removing pollutants (more than 80%) from the pharmaceutical industry like CBZ and SMX. Moreover, the ME-FBR performance revealed the impact of selecting an anode potential by efficiently removing both pollutants at + 200 mV. The high TOC removal efficiency also demonstrated that electrostimulation of electroactive bacteria in ME-FBR could overcome the expected microbial inhibition due to the presence of CBZ and SMX. Cyclic voltammograms revealed the successful electron transfer between microbial biofilm and the fluid-like electrode bed throughout the polarization tests. Finally, Vibrio fischeri-based ecotoxicity showed a 70% reduction after treating wastewater with a fluid-like anode (+ 400 mV), revealing the promising performance of this bioelectrochemical approach.