Fungal treatment of metoprolol and its recalcitrant metabolite metoprolol acid in hospital wastewater: Biotransformation, sorption and ecotoxicological impact.

Hospital wastewater (HWW) effluents represent an important source of contaminants such as pharmaceutical compounds and their human metabolites. To better evaluate dedicated treatment of hospital effluents for pollutant mitigation, not only the parent compounds should be considered but also the intermediates generated during treatment. The metabolite metoprolol acid (MTPA) has been found in urban wastewaters at higher concentration than its parent compound metoprolol (MTP), being more recalcitrant to biodegradation. The aim of this study was to investigate degradation, transformation and sorption of the ß-blocker MTP, and its recalcitrant metabolite MTPA, during water treatment based on the fungi Ganoderma lucidum, Trametes versicolor and Pleurotus ostreatus. Fourteen intermediates were identified in MTP biotransformation while five of them also attributed to MTPA biodegradation and two to MTPA only. Their identification allowed their correlation in separate biotransformation pathways suggested. The highest degradation rate of metoprolol (up to 51%) and metoprolol acid (almost 77%) was found after 15-days treatment with Ganoderma lucidum, with an increase in toxicity up to 29% and 4%, respectively. This fungus was further selected for treating real HWW in a batch fluidized bed bioreactor (FBB). Treated wastewater and fungal biomass samples were used to evaluate the distribution of the target compounds and the intermediates identified between solid and liquid phases. While similar elimination capabilities were observed for the removal of metoprolol, and even higher for its persistent metabolite metoprolol acid, the extent on compound transformation diminished considerably compared with the study treating purified water: a high level of the persistent α-HMTP and TP240 were still present in effluent samples (15% and 6%, respectively), being both TPs present at high proportion (up to 28%) in fungal biomass. This is the first time that pharmaceutical TPs have been investigated in the fungal biomass.

Fungal biodegradation of the N-nitrosodimethylamine precursors venlafaxine and O-desmethylvenlafaxine in water.

Antidepressant drugs such as Venlafaxine (VFX) and O-desmethylvenlafaxine (ODMVFX) are emerging contaminants that are commonly detected in aquatic environments, since conventional wastewater treatment plants are unable to completely remove them. They can be precursors of hazardous by-products, such as the carcinogenic N-nitrosodimethylamine (NDMA), generated upon water chlorination, as they contain the dimethylamino moiety, necessary for the formation of NDMA. In this study, the capability of three white rot fungi (Trametes versicolor, Ganoderma lucidum and Pleurotus ostreatus) to remove both antidepressants from water and to decrease NDMA formation potential was investigated. Furthermore, transformation by-products (TPs) generated along the treatment process were elucidated and also correlated with their NDMA formation potential. Very promising results were obtained for T. versicolor and G. lucidum, both being able to remove up to 100% of ODMVFX. In the case of VFX, which is very recalcitrant to conventional wastewater treatment, a 70% of removal was achieved by T. versicolor, along with a reduction in NDMA formation potential, thus decreasing the associated problems for human health and the environment. However, the NDMA formation potential remained practically constant during treatment with G. lucidum despite of the equally high VFX removal (70%). This difference was attributed to the generation of different TPs during both fungal treatments. For example, G. lucidum generated more ODMVFX, which actually has a higher NDMA formation potential than the parent compound itself.

Stropharia rugosoannulata and Gymnopilus luteofolius: Promising fungal species for pharmaceutical biodegradation in contaminated water.

Pharmaceuticals are environmental micropollutants that pose an emerging challenge because they are poorly eliminated in conventional wastewater treatment plants. Over the last decade, many attempts have been made to solve this problem, and wastewater fungal treatment is a promising alternative. In this study, six different ligninolytic fungi (Trametes versicolor, Ganoderma lucidum, Irpex lacteus, Stropharia rugosoannulata, Gymnopilus luteofolius and Agrocybe erebia) were studied as bioremediation candidates for the removal and degradation of six recalcitrant pharmaceutical micropollutants: Carbamazepine (CBZ), Venlafaxine (VFX), Iopromide (IPD), Diclofenac (DCF), Cyclophosphamide (CFD) and Ifosfamide (IFD). Self-immobilization in a pellet shape was achieved for all fungal mycelia (which was the first time that this was reported for S. rugosoannulata, G. luteofolius, and A. erebia). Biodegradation achievement was greater than 90% for IPD with G. luteofolius and greater than 70% for CBZ with S. rugosoannulata, which suggests a great potential for this alternative biological treatment. Besides, this was the first report where fungal treatment achieved CFD and IFD removals greater than 20% for the treatment with T. versicolor, G. lucidum and S. rugosoannulata.

Preliminary evaluation of Pleurotus ostreatus for the removal of selected pharmaceuticals from hospital wastewater.

The fungus Pleurotus ostreatus was investigated to assess its ability to remove diclofenac, ketoprofen, and atenolol spiked at 10 mg/L each one in hospital wastewater. The degradation test was carried out in a fluidized bed bioreactor testing both the batch and the continuous mode (hydraulic retention time in the range 1.63-3 days). In batch mode, diclofenac disappeared in less than 24 h, ketoprofen was degraded up to almost 50% in 5 days while atenolol was not removed. In continuous mode, diclofenac and ketoprofen removals were about 100% and 70% respectively; atenolol degradation was negligible during the first 20 days but it increased up to 60% after a peak of laccase production and notable biomass growth. In order to identify the enzymatic system involved, further experiments were carried out in flasks. Purified laccase completely transformed atenolol and diclofenac in less than 5 h, but not ketoprofen. In vivo experiments suggested that cytochrome P450 could be involved in diclofenac and ketoprofen degradation, while partial correlation studies confirmed the role of laccase in atenolol and diclofenac degradation. Two intermediates of diclofenac and ketoprofen were detected by nuclear magnetic resonance. Moreover P. ostreatus was able to reduce chemical oxygen demand of the hospital wastewater which is an important advantage comparing to other fungi in order to develop a wastewater treatment process. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1529-1537, 2017.