ABSTRACT
Two aerobic granular sludge (AGS) sequential batch reactors were operated at a mild (15 °C) temperature for 180 days. One of those bioreactors was exposed to a mixture of diclofenac, naproxen, trimethoprim, and carbamazepine. The AGS system, operating under pressure from emerging contaminants, showed a decrease in COD, BOD5, and TN removal capacity, mainly observed during the first 100 days, in comparison with the removal ratios detected in the control bioreactor. After an acclimatisation period, the removal reached high-quality effluent for COD and TN, close to 95% and 90%, respectively. In the steady-state period, trimethoprim and diclofenac were successfully removed with values around 50%, while carbamazepine and naproxen were more recalcitrant. The dominant bacterial OTUs were affected by the presence of a mixture of pharmaceutical compounds, under which the dominant phylotypes changed to OTUs classified among the Pseudomonas, Gemmobacter, and Comamonadaceae. The RT-qPCR and qPCR results showed the deep effects of pharmaceutical compounds on the number of copies of target genes. Statistical analyses allowed for linking the total and active microbial communities with the physico-chemical performance, describing the effects of pharmaceutical compounds in pollution degradation, as well as the successful adaptation of the system to treat wastewater in the presence of toxic compounds.
ABSTRACT
A bacterial strain, designated strain LP01(T), was isolated from a laboratory-scale microcosm packed with a mixture of soil and sewage sludge compost designed to study the evolution of microbial biodiversity over time. The bacterial strain was selected for its potential ability to store polyhydroxyalkanoates (PHAs) as intracellular granules. The cells were aerobic, Gram-stain-negative, non-endospore-forming motile rods. Phylogenetically, the strain was classified within the genus Massilia, as its 16S rRNA gene sequence had similarity of 99.2â% with respect to those of Massilia albidiflava DSM 17472(T) and M. lutea DSM 17473(T). DNA-DNA hybridization showed low relatedness of strain LP01(T) to the type strains of other, phylogenetically related species of the genus Massilia. It contained Q-8 as the predominant ubiquinone and summed feature 3 (C16â:â1ω7c and/or iso-C15â:â0 2-OH) as the major fatty acid(s). It was found to contain small amounts of the fatty acids C18â:â0 and C14â:â0 2-OH, a feature that served to distinguish it from its closest phylogenetic relatives within the genus Massilia. The DNA G+C content was 66.0 mol%. Phylogenetic, phenotypic and chemotaxonomic data obtained in this study suggest that strain LP01(T) represents a novel species of the genus Massilia, for which the name Massilia umbonata sp. nov. is proposed. The type strain is LP01(T) (â=âCECT 7753(T)â=âDSM 26121(T)).
