assisted-selection-biomarkers-linear-discriminant-analysis-effect

Assisted Selection of Biomarkers by Linear Discriminant Analysis Effect Size (LEfSe) in Microbiome Data

There is growing attention toward closed biological genomes in the environment and in health. To explore and reveal the intergroup differences among ...

Tianjin Research Institute for Water Transport Engineering, M.O.T.

Nitrous oxide (NO) generated from wastewater treatment plants (WWTPs) has drawn attention due to its high emission load and significant greenhouse effect. In the present study, NO emissions from a pilot-scale Carrousel oxidation ditch under various chemical oxygen demand (COD) to nitrogen ratio (COD/N) and aeration rates were systematically investigated. The highest NO emission factor was 0.142 ± 0.013%, at COD/N of 5 and aeration rate of 1.8 m h, which was much lower than the majority of previous studies. The results could be attributed to the high internal recycle ratio of the oxidation ditch process which lightened the burden of influent load to the system. The profiles of NO emissions and dissolved NO concentration along the channels showed a distinct spatial variation that NO emissions primarily occurred in the aeration zones due to the air stripping effect. However, both the aeration and anoxic zones contributed to NO generation due to autotrophic nitrification (AN), which was considered to be the main NO generation process. In addition, two simulated shock-load conditions, ammonia overload shock and aeration failure shock, were carried out to explore the response of the biological nitrogen removal (BNR) system. The results indicated that both shock-loads lead to excessive NO emissions, especially at higher aeration rates, which could be explained by the improved NO generation by AN process during the shock-load period. This study offered new insights into the role of operational parameters to NO emission and the alternative approach for NO mitigation during both the steady-state operation and shock-load conditions in the oxidation ditch process.

Nitrous oxide (NO) emissions from a pilot-scale oxidation ditch under different COD/N ratios, aeration rates and two shock-load conditions.

This study investigated the environmental effects of two familiar emerging contaminants, sulfamethoxazole (SMX) and erythromycin (ERY), and their mixture (10:1 /) using a green microalga, . The cell density, pigment content, and the activities of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) glutathione peroxidase (GSH-Px), and glutathione S-transferase (GST) were analyzed. The calculated EC values of SMX, ERY, and their mixture after 96 h were 0.49, 0.044, and 0.06 mg/L, respectively. High concentrations of antibiotics lead to a decrease in chlorophyll a and total carotenoid content, affecting the ability to photosynthesize ROS scavenging capacity. This may be a factor leading to the inhibition of algal growth. When  was exposed to SMX and the mixture, SOD and CAT increased to resist oxidative damage, while the activities of GSH and GST decreased, suggesting that this algae's antioxidant system was unbalanced due to oxidative stress.  reduced the ERY-induced ROS by increasing the activities of SOD, GSH, and GST. The difference in the contents of nonenzymatic antioxidants and enzyme antioxidants in  indicated the antioxidant mechanisms to SMX and ERY were not identical. This study provides insights into the oxidative stress process in  under different antibiotics.

Combined Effects of Sulfamethoxazole and Erythromycin on a Freshwater Microalga, : Toxicity and Oxidative Stress.

Nitrous oxide (NO) emission from wastewater treatment plants (WWTPs) requires urgent mitigation because of its significant contribution to the greenhouse effect. In this study, bioaugmentation was applied in a pilot-scale oxidation ditch with the aerobic denitrifying bacteria strain PCN-1 immobilized on polyurethane biocarriers, which demonstrated effective NO mitigation. Microbial community analysis suggested that the bioaugmentation facilitated a symbiotic relationship of the bacterial populations between the activated sludge and the biocarriers. The denitrifying bacteria with well-known NO reducing capabilities predominated on the biocarriers. Correspondingly, the increases of denitrifying genes and NO and NO reductase provided evidence for the enhanced genetic potential for NO and NO reduction. Besides, the enriched comammox Nitrospira on the biocarriers is proposed as another significant driver for NO mitigation by avoiding nitrite accumulation. In addition, the bioaugmentation enhanced the stability and recovery capability of the system in the ammonia overload and aeration failure shock tests.

Mitigating NO and NO emissions from a pilot-scale oxidation ditch using bioaugmentation of immobilized aerobic denitrifying bacteria.

Wastewater treatment plants (WWTP) are regarded as the last barriers for the release of incompletely separated and recycled nanoparticles (NPs) into the environment. Despite the importance and ubiquity of microbial extracellular polymeric substances (EPSs) in the complex wastewater matrix, the interaction between NPs and EPSs of anaerobic microflora involved in wastewater treatment and the resultant impact on the biomass metabolomics are unclear. Thus, the impacts of different metal oxide (TiO, ZnO, and CuO) NPs on functional bacteria in anaerobic granular sludge (AGS) and the possible toxicity mechanisms were investigated. In particular, the binding quality, enhanced resistance mechanism, and chemical fractional contribution of EPSs from AGS against the nanotoxicity of different NPs was assessed. The results showed that CuO NPs caused the most severe inhibition towards acetoclastic and hydrogenotrophic methanogens, followed by ZnO NPs, whereas TiO NPs caused no inhibition to methanogenesis. Excessive EPS production, especially the protein-like substances, was an effective strategy for reducing certain NPs' toxicity by immobilizing NPs away from AGS cells, whereas the metabolism restriction on inner microorganisms of AGS induced by CuO NPs can deteriorate the protective role of EPS, indicating that the roles of EPS may not be amenable to generalizations. Further investigations with lactate dehydrogenase (LDH) and reactive oxygen species (ROS) assays indicated that there are greatly essential differences between the toxicity mechanisms of metal NPs to AGS, which varied depending on the NPs' type and dosage. In addition, dynamic changes in the responses of EPS content to different NPs can result in a significant shift in methanogenic and acidogenic microbial communities. Thus, the production and composition of EPSs will be a key factor in determining the fate and potential effect of NPs in the complex biological matrix. In conclusion, this study broadens the understanding of the inhibition mechanisms of metal oxide NPs on the AGS process, and the influence of EPSs on the fate, behavior, and toxicity of NPs.

Fang Chang

Marine Resources Research Centre

Tianjin Research Institute for Water Transport Engineering, M.O.T.

Assisted Selection of Biomarkers by Linear Discriminant Analysis Effect Size (LEfSe) in Microbiome Data

Fang Chang

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Marine Resources Research Centre

Tianjin Research Institute for Water Transport Engineering, M.O.T.

Assisted Selection of Biomarkers by Linear Discriminant Analysis Effect Size (LEfSe) in Microbiome Data

Marine Resources Research Centre