Shifts of system performance and microbial community structure in a constructed wetland after exposing silver nanoparticles.

The increasing utilization of silver nanoparticles (Ag NPs) in industry and commerce inevitably raises its release into wastewater. In this work, effects of Ag NPs on system performance and microbial community along the way of a vertical flow constructed wetland (VFCW) were investigated, along with the removal and fate of Ag NPs within the system. Results showed that the performance of control wetland kept stable during the experimental period, and the top substrate layer (soil layer) of wetland could remove most of pollutants in the influent. The study also suggested that addition of Ag NPs did not significantly affect organic matters removal. However, adverse effects were observed on the nitrogen and phosphorus removal. Removal efficiencies of TN, NH4+-N and TP approximately obviously reduced by approximately 10.10%, 8.42% and 28.35% respectively in contrast to before dosing after exposing 100 µg/L Ag NPs for 94 d, while the no dosing wetland with the stable performance. It was found that Ag NPs accumulated in the upper soil layer more than in the lower soil layer, and Ag NPs could enter into the plant tissues. After continuous input of Ag NPs, removal efficiency of Ag NPs was measured as 95.72%, which showed that the CW could effectively remove Ag NPs from the wastewater. The high-throughput sequencing results revealed that Ag NPs caused the shifts in microbial community structures and changed the relative abundances of key functional bacteria, which finally resulted in a lower efficiency of biological nitrogen and phosphorus removal.

Metabolomics revealed diurnal heat stress and zinc supplementation-induced changes in amino acid, lipid, and microbial metabolism.

Heat stress (HS) dramatically disrupts the events in energy and nutrient metabolism, many of which requires zinc (Zn) as a cofactor. In this study, metabolic effects of HS and Zn supplementation were evaluated by examining growth performance, blood chemistry, and metabolomes of crossbred gilts fed with ZnNeg (no Zn supplementation), ZnIO (120 ppm ZnSO4), or ZnAA (60 ppm ZnSO4 + 60 ppm zinc amino acid complex) diets under diurnal HS or thermal-neutral (TN) condition. The results showed that growth performance was reduced by HS but not by Zn supplementation. Among measured serum biochemicals, HS was found to increase creatinine but decrease blood urea nitrogen (BUN) level. Metabolomic analysis indicated that HS greatly affected diverse metabolites associated with amino acid, lipid, and microbial metabolism, including urea cycle metabolites, essential amino acids, phospholipids, medium-chain dicarboxylic acids, fatty acid amides, and secondary bile acids. More importantly, many changes in these metabolite markers were correlated with both acute and adaptive responses to HS. Relative to HS-induced metabolic effects, Zn supplementation-associated effects were much more limited. A prominent observation was that ZnIO diet, potentially through its influences on microbial metabolism, yielded different responses to HS compared with two other diets, which included higher levels of short-chain fatty acids (SCFAs) in cecal fluid and higher levels of lysine in the liver and feces. Overall, comprehensive metabolomic analysis identified novel metabolite markers associated with HS and Zn supplementation, which could guide further investigation on the mechanisms of these metabolic effects.

Evaluation of the properties of a tissue conditioner containing origanum oil as an antifungal additive.

STATEMENT OF PROBLEM: Adherence and colonization of Candida albicans on tissue conditioners is common and results in irritation of the denture-bearing mucosa. PURPOSE: The purpose of this study was to investigate the antifungal activity and properties of a tissue conditioner by incorporating origanum oil. MATERIAL AND METHODS: Origanum oil at varying concentrations was incorporated into a poly(methyl methacrylate) based tissue conditioner (Visco-gel), and its antifungal activity against Candida albicans was evaluated at 1 day and 1 week by using the agar punch well method. The adherence of Candida albicans, surface roughness, tensile strength, and bond strength of the tissue conditioner with an optimized origanum oil concentration were evaluated. The data were subjected to 2-way ANOVA (α=.05). RESULTS: Sixty vol% origanum oil in tissue conditioner (Visco-gel) showed a mean inhibitory zone of 21.00 ± 1.58 mm at 1 day and 13.44 ± 0.88 mm at 1 week. The control group showed 90 ± 6.80 yeast cells/mm(2) at 1 day and 165 ± 7.63 yeast cells/mm(2) at 1 week, whereas the group with origanum oil showed 16 ± 1.15 yeast cells/mm(2) at 1 day and 32 ± 4.00 yeast cells/mm(2) at 1 week. Surface roughness was less with the incorporation of origanum oil. Tensile strength at 1 day was 0.91 ± 0.52 N for the control group, whereas the group with origanum oil showed 0.16 ± 0.05 N. At 1 day, the bond strength of 3.97 ± 0.75 MPa was observed with control specimens, whereas tissue conditioner with origanum oil showed a bond strength of 3.73 ± 0.65 MPa. CONCLUSIONS: Within the limitations of this in vitro study, origanum oil can be used as an additive to tissue conditioner to reduce the adherence of Candida albicans without significantly affecting its bond strength to heat-polymerized acrylic resin.