A conceptual framework modeling of functional microbial communities in wastewater treatment electro-bioreactors.

Understanding the microbial ecology of a system allows linking members of the community and their metabolic functions to the performance of the wastewater bioreactor. This study provided a comprehensive conceptual framework for microbial communities in wastewater treatment electro-bioreactors (EBRs). The model was based on data acquired from monitoring the effect of altering different bioreactor operational parameters, such as current density and hydraulic retention time, on the microbial communities of an EBR and its nutrient removal efficiency. The model was also based on the 16S rRNA gene high-throughput sequencing data analysis and bioreactor efficiency data. The collective data clearly demonstrated that applying various electric currents affected the microbial community composition and stability and the reactor efficiency in terms of chemical oxygen demand, N and P removals. Moreover, a schematic that recommends operating conditions that are tailored to the type of wastewater that needs to be treated based on the functional microbial communities enriched at specific operating conditions was suggested. In this study, a conceptual model as a simplified representation of the behavior of microbial communities in EBRs was developed. The proposed conceptual model can be used to predict how biological treatment of wastewater in EBRs can be improved by varying several operating conditions.

Improved electrochemical detection of levofloxacin in diverse aquatic samples using 3D flower-like Co@CaPO4 nanospheres.

The misuse of antibiotics has become a concerning environmental issue, posing a significant threat to public health. Levofloxacin (LFX), a fluoroquinolone antibiotic, is particularly worrisome due to its detrimental impact on human health and the ecosystem. Therefore, the selective and accurate identification of LFX is of utmost importance. In this study, we have developed an electrochemical sensor based on cobalt-doped calcium phosphate (Co@CaHPO) for the sensitive and selective detection of LFX in various water samples. Under optimized conditions, the Co@CaHPO-modified glassy carbon electrode (GCE) exhibited exceptional electrochemical activity, low charge transfer resistance, and a fast electron transfer rate, outperforming the unmodified GCE. The proposed Co@CaHPO-modified GCE demonstrated remarkable electrochemical characteristics, including a wide linear range (0.3-460 µM) and a lower detection limit (0.151 µM) with high sensitivity (0.676 µAµM-1 cm2). This detection approach may enable the direct detection of LFX in the pharmaceutical environment. Furthermore, the resulting sensor exhibited good selectivity, excellent cyclic and storage stability, reproducibility, and repeatability. The practical application of this LFX sensor can be extended to various water samples, yielding reliable and satisfactory results.

In vitro α-glucosidase inhibitory activity of Tamarix nilotica shoot extracts and fractions.

α-glucosidase inhibitors represent an important class of type 2 antidiabetic drugs and they act by lowering postprandial hyperglycemia. Today, only three synthetic inhibitors exist on the market, and there is a need for novel, natural and more efficient molecules exhibiting this activity. In this study, we investigated the ability of Tamarix nilotica ethanolic and aqueous shoot extracts, as well as methanolic fractions prepared from aqueous crude extracts to inhibit α-glucosidase. Both, 50% ethanol and aqueous extracts inhibited α-glucosidase in a concentration-dependent manner, with IC50 values of 12.5 µg/mL and 24.8 µg/mL, respectively. Importantly, α-glucosidase inhibitory activity observed in the T. nilotica crude extracts was considerably higher than pure acarbose (IC50 = 151.1 µg/mL), the most highly prescribed α-glucosidase inhibitor on the market. When T. nilotica crude extracts were fractionated using methanol, enhanced α-glucosidase inhibitory activity was observed in general, with the highest observed α-glucosidase inhibitory activity in the 30% methanol fraction (IC50 = 5.21 µg/mL). Kinetic studies further revealed a competitive reversible mechanism of inhibition by the plant extract. The phytochemical profiles of 50% ethanol extracts, aqueous extracts, and the methanolic fractions were investigated and compared using a metabolomics approach. Statistical analysis revealed significant differences in the contents of the crude extracts and fractions and potentially identified the molecules that were most responsible for these observed variations. Higher α-glucosidase inhibitory activity was associated with an enrichment of terpenoids, fatty acids, and flavonoids. Among the identified molecules, active compounds with known α-glucosidase inhibitory activity were detected, including unsaturated fatty acids, triterpenoids, and flavonoid glycosides. These results put forward T. nilotica as a therapeutic plant for type 2 diabetes and a source of α-glucosidase inhibitors.

A metabolomics approach to evaluate the effect of lyophilization versus oven drying on the chemical composition of plant extracts.

Lyophilization is the "gold standard" for drying plant extracts, which is important in preserving their quality and extending their shelf-life. Compared to other methods of drying plant extracts, lyophilization is costlier due to equipment, material and operational expenses. An alternative method is post-extraction oven-drying, but the effects of this process on extract quality are unknown. In this study, crude extracts from Arthrocnemum macrostachyum shoots were compared using three post-extraction drying methods (lyophilization and oven drying at 40 and 60 °C) and two extraction solvents (water and aqueous 50% ethanol). Untargeted metabolomics coupled with chemometrics analysis revealed that post extraction oven-drying resulted in the loss of up to 27% of molecular features when compared to lyophilization in water extracts only. In contrast, only 3% of molecular features were lost in aqueous 50% ethanol extracts when subjected to oven drying. That is to say, ethanol used as a solvent has a stabilizing effect on metabolites and enhances their resistance to thermal transformation in the oven. Collectively, oven-drying of extracts was as effective as lyophilization in preserving metabolites in extracts only when 50% ethanol was used as a solvent. The results presented in this paper demonstrate the value of selecting solvent-appropriate post-extraction drying methods.

Impact of current density on the function and microbial community structure in electro-bioreactors.

The assessment of bacterial communities in wastewater electro-bioreactors has garnered attention to improve efficiency of wastewater treatment plant (WWTP) processes. This study evaluated the effects of applying different current densities on the function and microbial community structure of an electro-bioreactor by measuring nutrient removal efficiency and analyzing 16S rRNA gene high-throughput sequencing. The electro-bioreactors at current density of 3, 5 and 7 A/m2 resulted in an enrichment of operational taxonomic units belonging to distinct functional bacterial families such as (Nitrospiraceae: 8.5, 12.5 and 12.6% relative abundance, respectively) and (Rhodocyclaceae: 8.1, 8.8 and 9.7% relative abundance, respectively), leading to efficient N-removal (>98%) and P-removal (>98%) higher than the control bioreactor (9.6 and 5.0%, respectively). Applying different electric currents proved to affect microbial community composition in electro-bioreactors. The results reported here could prove to be valuable for process control, optimization and improving WWTPs design and operation.

Effect of hydraulic retention time on microbial community structure in wastewater treatment electro-bioreactors.

The impact of hydraulic retention time (HRT) on the performance and microbial community structure of control and electro-bioreactors was investigated. Control bioreactors and electro-bioreactors were operated at HRT ranging between 6 and 75 hr. The total bacterial counts in addition to the removal efficiency of NH4+ -N, sCOD, and PO43- -P was assessed in all the reactors tested. In addition, Illumina sequencing was performed to determine the microbial communities that developed in these reactors under each HRT condition. Phylogenetic analysis showed that Proteobacteria and Bacteroidetes were the dominant phyla in those reactors. In addition, Nitrospira sp. and Pseudomonas sp. were found to be present in electro-bioreactors with higher relative abundance than in control bioreactors. The results presented here are the first to determine what different microbial communities in wastewater electro-bioreactors due to the application of an electric current under different HRTs.

Assessment of Microbial Community Structure and Function in Serially Passaged Wastewater Electro-Bioreactor Sludge: An Approach to Enhance Sludge Settleability.

Several studies have been carried out to understand bulking phenomena and the importance of environmental factors on sludge settling characteristics. The main objective of this study was to carry out functional characterization of microbial community structure of wastewater electro-bioreactor sludge as it undergoes serial passaging in the presence or absence of a current density over 15 days. Illumina MiSeq sequencing and QIIME were used to assess sludge microbial community shifts over time. (α) and (ß) diversity analysis were conducted to assess the microbial diversity in electro-bioreactors. A phylogeny-based weighted UniFrac distance analysis was used to compare between bacterial communities while BIO-ENV trend and Spearman's rank correlation analysis were performed to investigate how reactor operational parameters correlated with bacterial community diversity. Results showed that the removal efficiency of soluble chemical oxygen demand (sCOD) ranged from 91-97%, while phosphorous (PO43--P) removal was approximately 99%. Phylogenetic analysis revealed stark differences in the development of sludge microbial communities in the control and treatment reactor. There was no mention of any studies aimed at characterizing functional microbial communities under electric field and the results communicated here are the first, to our knowledge, that address this gap in the literature.