ABSTRACT
Triphenyltin (TPT) is widely used in crop pest control and ship antifouling coatings, which leads to its entry into aquatic environment and poses a threat to aquatic organisms. However, the effects of TPT on the early life stages of wild fish in natural water environments remains unclear. The aim of this study was to assess the toxic effects of TPT on the early life stages of fish under two different environments: field investigation and laboratory experiment. The occurrence of deformities in wild fish embryos and larvae in the Three Gorges Reservoir (TGR) and the developmental toxicity of TPT at different concentrations (0, 0.15, 1.5 and 15 µg Sn/L) to zebrafish embryos and larvae were observed. The results showed that TPT content was higher in wild larvae, reaching 27.21 ng Sn/g w, and the malformation of wild fish larvae mainly occurred in the eyes and spine under natural water environment. Controlled experiment exposure of zebrafish larvae to TPT also resulted in eye and spinal deformities. Gene expression analysis showed that compared with the control group, the expression levels of genes related to eye development (sox2, otx2, stra6 and rx1) and spine development (sox9a and bmp2b) were significantly up-regulated in the 15 µg Sn/L exposure group, which may be the main cause of eye and spine deformity in the early development stage of fish. In addition, the molecular docking results further elucidate that the strong hydrophobic and electrostatic interactions between TPT and protein residues are the main mechanism of TPT induced abnormal gene expression. Based on these results, it can be inferred that TPT is one of the teratogenic factors of abnormal eye and spine development in the early life stage of fish in the TGR. These findings have important implications for understanding the toxicity of TPT on fish.
Subject(s)
Embryo, Nonmammalian , Larva , Organotin Compounds , Water Pollutants, Chemical , Zebrafish , Animals , Organotin Compounds/toxicity , Water Pollutants, Chemical/toxicity , Larva/drug effects , Embryo, Nonmammalian/drug effects , Spine/drug effects , Spine/abnormalities , Eye/drug effects , Eye/embryologyABSTRACT
Metal pollution has raised negative impact on microbes, but little is known about the distribution and co-occurrence pattern of bacterial, fungal and archaeal communities along the soil profiles at multiple metal contamination sites. Here, we characterized the variations of metal concentrations and microbial communities with soil depth along five deep bores at the Tanghe Sewage Reservoir, a typical metal contamination area on the North China Plain. Co, Cd, Mg, Se, and Li were identified as the major contaminants in this area, and the pollution load index was 1.88, 1.54 and 1.62 in the shallow layer (0-0.6 m), deep layer (>2.0 m) and middle layer (0.6-2.0 m), respectively. The diversities and compositions of bacterial, archaeal and fungal communities varied significantly along the soil profiles. Deterministic process played a crucial role in shaping the difference of microbial community compositions among different soil layers, in which metal levels contributed more than soil physiochemical parameters. Furthermore, the interspecific co-occurrence network was most complex in the middle layer, indicating that metal pollution could decrease microbial network complexity. Bacterial keystone species in the co-occurrence networks showed both positive and negative correlations with polluted metals, whereas most archaeal and fungal keystone species were negatively related to multiple metals. These findings increased our understanding of distribution patterns, co-occurrence networks and environmental drivers of microbial communities in metal pollution soils.
Subject(s)
Mycobiome , Soil Pollutants , Archaea , Soil/chemistry , Soil Pollutants/analysis , Bacteria , Metals/pharmacology , Soil MicrobiologyABSTRACT
It is a well-established fact that aerobic denitrifying strains are profoundly affected by antibiotics, but bacterium performing simultaneous aerobic denitrification and antibiotic degradation is hardly reported. Here, a typical aerobic denitrifying bacterium Pseudomonas aeruginosa PCN-2 was discovered to be capable of sulfamethoxazole (SMX) degradation. The results showed that nitrate removal efficiency was decreased from 100% to 88.12%, but the resistance of strain PCN-2 to SMX stress was enhanced with the increment of SMX concentration from 0 to 100 mg/L. Transcriptome analysis revealed that the down-regulation of energy metabolism pathways rather than the denitrifying functional genes was responsible for the suppressed nitrogen removal, while the up-regulation of antibiotic resistance pathways (e.g., biofilm formation, multi-drug efflux system, and quorum sensing) ensured the survival of bacterium and the carrying out of aerobic denitrification. Intriguingly, strain PCN-2 could degrade SMX during aerobic denitrification. Seven metabolites were identified by the UHPLC-MS, and three degradation pathways (which includes a new pathway that has never been reported) was proposed combined with the expressions of drug metabolic genes (e.g., cytP450, FMN, ALDH and NAT). This work provides a mechanistic understanding of the metabolic adaption of strain PCN-2 under SMX stress, which provided a broader idea for the treatment of SMX-containing wastewater.
Subject(s)
Denitrification , Pseudomonas aeruginosa , Pseudomonas aeruginosa/metabolism , Sulfamethoxazole/pharmacology , Sulfamethoxazole/metabolism , Aerobiosis , Nitrogen/metabolism , Gene Expression ProfilingABSTRACT
Zinc oxide nanoparticles (ZnO NPs) show adverse impacts on aerobic denitrifying bacteria, little is known about the response of these bacteria to ZnO NPs exposure at cellular level. This study assessed the multiple responses of Pseudomonas aeruginosa PCN-2 under ZnO NPs exposure. We demonstrated that ZnO NPs exposure could inhibit the intracellular metabolism and stimulate the antioxidant defence capability of PCN-2. At lower exposure concentration (5 mg/L), exogenous ROS generated and resulted in the inhibition of pyruvate metabolism and citrate cycle, which caused deficient energy for aerobic denitrification. At higher concentrations (50 mg/L), endogenous ROS additionally generated and triggered to stronger down-regulation of oxidative phosphorylation, which caused suppressed electron transfers for aerobic denitrification. Meanwhile, ZnO NPs exposure promoted EPS production and biofilm formation, and antioxidases was especially particularly stimulated at higher concentration. Our findings are significant for understanding of microbial bacterial susceptibility, tolerance and resistance under the exposure of ZnO NPs.
Aerobic denitrification is suppressed with increased ZnO NPs concentrations.ZnO NPs induce inhibition of pyruvate metabolism and citrate cycle at 5 mg/L.Higher ZnO NPs concentration induces the generation of endogenous and exogenous ROS.Higher NPs concentration leads to the trigger of antioxidant system.ZnO NPs stimulate metabolisms of EPS production.
Subject(s)
Metal Nanoparticles , Nanoparticles , Zinc Oxide , Denitrification , Reactive Oxygen Species , TranscriptomeABSTRACT
Performance and molecular changes of an aerobic denitrifying phosphorus accumulating bacteria Pseudomonas psychrophila HA-2 have been investigated under different temperatures and ZnO nanoparticles (NPs) exposures. Strain HA-2 removed 95.7% of total nitrogen (TN) and 24.6% of phosphorus at 10 °C, which was attributed to the joint up-regulation of intracellular energy metabolism and ribosome. Moreover, with the increase of ZnO NPs from 0 to 100 mg/L, TN and phosphurs removal efficiencies decreased from 95.7% to 44.5% and 24.6% to 6.8% at 10 °C, respectively, whereas phosphorus removal rate increased from 10.5% to 24.5% at 20 °C. Further transcriptomics and proteomics revealed that significant down-regulation of purine and amino acid metabolisms was the main reason for the inhibitory effect at 10 °C, while the up-regulation of antioxidant pathways and functional genes expressions was responsible for the promoted phosphorus accumulation at 20 °C. This study provides a potential solution for improving biological nutrients removal processes in winter months.
Subject(s)
Nanoparticles , Zinc Oxide , Bacteria, Aerobic/metabolism , Bioreactors/microbiology , Denitrification , Nitrogen/metabolism , Phosphorus/metabolism , Pseudomonas/metabolism , Temperature , Zinc Oxide/pharmacologyABSTRACT
Aerobic denitrification has been proved to be profoundly affected by temperature and antibiotics, but little is known about how aerobic denitrifiers respond to temperature and antibiotic stress. In this study, the nitrate reduction performance and the intracellular metabolism by a psychrotolerant aerobic denitrifying bacteria, named Pseudomonas psychrophila RNC-1, were systematically investigated at different temperatures (10 °C, 20 °C, 30 °C) and different sulfamethoxazole (SMX) concentrations (0 mg/L, 0.1 mg/L, 0.5 mg/L, 1.0 mg/L, and 5.0 mg/L). The results showed that strain RNC-1 performed satisfactory nitrate removal at 10 °C and 20 °C, but its growth was significantly inhibited at 30 °C. Nitrate removal by strain RNC-1 was slightly promoted in the presence of 0.5 mg/L SMX, whereas it was significantly suppressed with 5.0 mg/L SMX. Nitrogen balance analysis indicated that assimilatory nitrate reduction and dissimilatory aerobic denitrification jointly dominated in the nitrate removal process of strain RNC-1, in which the inhibition effected on assimilation process was much higher than that on the aerobic denitrification process under SMX exposure. Further transcriptomics and proteomics analysis revealed that the psychrotolerant mechanism of strain RNC-1 could be attributed to the up-regulation of RNA translation, energy metabolism, ABC transporters and the over-expression of cold shock proteins, while the down-regulation of oxidative phosphorylation pathway was the primary reason for the deteriorative cell growth at 30 °C. The promotion of nitrate reduction with 0.5 mg/L SMX was related to the up-regulation of amino acid metabolism pathways, while the down-regulation of folate cycle, glycolysis/gluconeogenesis and bacterial chemotaxis pathways were responsible for the inhibition effect at 5.0 mg/L SMX. This work provides a mechanistic understanding of the metabolic adaption of strain RNC-1 under different stress, which is of significance for its application in nitrogen contaminated wastewater treatment processes.
Subject(s)
Denitrification , Nitrates , Aerobiosis , Anti-Bacterial Agents/pharmacology , Nitrogen/chemistry , Proteomics , Pseudomonas , TranscriptomeABSTRACT
The proper choice of dissolved oxygen (DO) is important in aerobic treatment. In this paper, a multi-stage vertical variable diameter membrane bioreactor was developed to treat pharmaceutical wastewater containing 6-APA and ceftriaxone sodium. In the 180 days of operation, the performance of COD, BOD5, 6-APA, ceftriaxone sodium removal, sludge index, and microbial enzyme activity under different DOs (from 0.5 to 6.0 mg/L) were investigated. The results showed that the optimal range of DO was 1.5-2.1 mg/L, and the highest removal rates of COD and BOD5 were observed 87.3%±2.4% and 95.3%±1.8%, the corresponding effluent COD and BOD5 were 189 mg/L and 24 mg/L, respectively. To reduce the energy consumption and ensure stability of DO in the reactor, a control strategy based on an improved differential evolution BP fuzzy neural network was built and found that the performance and cost of the controlled DO were improved effectively than that of uncontrolled DO.
Subject(s)
Pharmaceutical Preparations , Wastewater , Bioreactors , Oxygen , Waste Disposal, FluidABSTRACT
This paper focused on the feasibility and performance of an up-flow anaerobic bio-electrochemical system (UBES) for treating sulfamethoxazole (SMX) antibiotic wastewater at different COD loading rates (LRs) from 2.02 ± 0.13 to 6.09 ± 0.14 kgCOD/(m3·d). Open-circuit UBES had a lower average COD removal rate of 62.4 ± 4.7% in Run2, and the accumulation of volatile fatty acid (VFA) was occurred. However, closed-circuit UBES can alleviate the accumulation of VFA (which was decreased from 720.4 to 102.4 mg/L), the highest average COD, SMX removal rates were 85.7 ± 3.2% and 73.7 ± 2.0%, respectively. The closed-circuit UBES can withstand more than 3 times LR than open-circuit UBES, which proved that the ability of microorganisms to resist toxic substance stress was strengthened. And the mathematical models for pollutants removal rate were established and well interpreted the results, which also can guide the operation of UBES.
ABSTRACT
In this study, a lab-scale multiple draft tubes airlift loop membrane bioreactor (Mt-ALMBR) was used for treating acidic 7-amino cephalosporanic acid (7-ACA) wastewater under different pHs (3.54-6.20) and hydraulic retention time (HRT) (48 h, 36 h, 24 h and 16 h). During about 200 days operation, under HRT of 48 h and pH condition about 6.0, the optimum average COD and BOD5 removal rates were reach to 84.4 ± 2.1% and 94.9 ± 0.8%, and the highest 7-ACA removal rate also observed as 77.6%. Biodegradation, membrane rejection, hydrolysis and sludge adsorption were the four main pathways of 7-ACA removal. With the increase of pH, biodegradation, membrane rejection and hydrolysis had significant positive impacts on 7-ACA removal, while adsorption had a negative impact. Moreover, mathematical models for 7-ACA removal rate and pH were calculated to guide the operation of Mt-ALMBR. Biodegradation was the main pathway to remove 7-ACA when pH was >4.17.
Subject(s)
Waste Disposal, Fluid , Wastewater , Amino Acids, Acidic , Bioreactors , SewageABSTRACT
This paper focused on the performance of an up-flow bio-electrochemical system (UBES) for treating the ß-lactams pharmaceutical wastewater under different hydraulic retention time (HRT). UBES is added a bio-electrochemical system below the three-phase separator based on up-flow anaerobic sludge blanket (UASB). Comparisons of chemical oxygen demand (COD) removal, accumulation of volatile fatty acid (VFA) and biogas production were investigated during the 316-day operation time, which was divided into five parts with HRT of 96â¯h, 72â¯h, 48â¯h, 36â¯h and 20â¯h, respectively. The average COD removal efficiency of UBES could reach 45.3⯱â¯7.5%, 72.2⯱â¯3.5%, 86.2⯱â¯1.4%, 75.9⯱â¯1.8% and 64.9⯱â¯2.0%, which were 2.4%, 6.1%, 6.4%, 10.2%, 8.7% more than those of UASB under different HRTs, respectively. Biogas production as well as methane production of UBES were significantly higher than UASB during the whole changing HRT process, the maximum methane yield of UBES was 0.31⯱â¯0.07â¯L/gCODremoved. Accumulation of VFA in UBES was discovered to be lighter than UASB, the minimum average VFA in UBES was 131.9⯱â¯18.5â¯mg/L, which was obtained at HRT of 48â¯h. These results proved that UBES can slow down the inhibition of VFA on methanogens to make sure a good performance on COD removal and biogas production than UASB. Moreover, the relationships between methane production and VFA, biogas production and COD consumption were analyzed. A cost and benefit were analyzed for evaluating the potential of UBES in practical applications compared with UASB. Finally, radial basis function neural network (RBFNN) model was developed and fitted well with the experimental data, which can be employed to predict the effluent quality of the UBES and UASB.