Protection of Si Nanowires against Aß Toxicity by the Inhibition of Aß Aggregation.

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by the accumulation of amyloid beta (Aß) plaques in the brain. Aß1-42 is the main component of Aß plaque, which is toxic to neuronal cells. Si nanowires (Si NWs) have the advantages of small particle size, high specific surface area, and good biocompatibility, and have potential application prospects in suppressing Aß aggregation. In this study, we employed the vapor-liquid-solid (VLS) growth mechanism to grow Si NWs using Au nanoparticles as catalysts in a plasma-enhanced chemical vapor deposition (PECVD) system. Subsequently, these Si NWs were transferred to a phosphoric acid buffer solution (PBS). We found that Si NWs significantly reduced cell death in PC12 cells (rat adrenal pheochromocytoma cells) induced by Aß1-42 oligomers via double staining with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and fluorescein diacetate/propyl iodide (FDA/PI). Most importantly, pre-incubated Si NWs largely prevented Aß1-42 oligomer-induced PC12 cell death, suggesting that Si NWs exerts an anti-Aß neuroprotective effect by inhibiting Aß aggregation. The analysis of Fourier Transform Infrared (FTIR) results demonstrates that Si NWs reduce the toxicity of fibrils and oligomers by intervening in the formation of ß-sheet structures, thereby protecting the viability of nerve cells. Our findings suggest that Si NWs may be a potential therapeutic agent for AD by protecting neuronal cells from the toxicity of Aß1-42.

The Ecology and Evolution of Amoeba-Bacterium Interactions.

Amoebae are protists that have complicated relationships with bacteria, covering the whole spectrum of symbiosis. Amoeba-bacterium interactions contribute to the study of predation, symbiosis, pathogenesis, and human health. Given the complexity of their relationships, it is necessary to understand the ecology and evolution of their interactions. In this paper, we provide an updated review of the current understanding of amoeba-bacterium interactions. We start by discussing the diversity of amoebae and their bacterial partners. We also define three types of ecological interactions between amoebae and bacteria and discuss their different outcomes. Finally, we focus on the implications of amoeba-bacterium interactions on human health, horizontal gene transfer, drinking water safety, and the evolution of symbiosis. In conclusion, amoeba-bacterium interactions are excellent model systems to investigate a wide range of scientific questions. Future studies should utilize advanced techniques to address research gaps, such as detecting hidden diversity, lack of amoeba genomes, and the impacts of amoeba predation on the microbiome.

Cooperation among nitrifying microorganisms promotes the irreversible biotransformation of sulfamonomethoxine.

Ammonia-oxidizing microorganisms, including AOA (ammonia-oxidizing archaea), AOB (ammonia-oxidizing bacteria), and Comammox (complete ammonia oxidization) Nitrospira, have been reported to possess the capability for the biotransformation of sulfonamide antibiotics. However, given that nitrifying microorganisms coexist and operate as communities in the nitrification process, it is surprising that there is a scarcity of studies investigating how their interactions would affect the biotransformation of sulfonamide antibiotics. This study aims to investigate the sulfamonomethoxine (SMM) removal efficiency and mechanisms among pure cultures of phylogenetically distinct nitrifiers and their combinations. Our findings revealed that AOA demonstrated the highest SMM removal efficiency and rate among the pure cultures, followed by Comammox Nitrospira, NOB, and AOB. However, the biotransformation of SMM by AOA N. gargensis is reversible, and the removal efficiency significantly decreased from 63.84 % at 167 h to 26.41 % at 807 h. On the contrary, the co-culture of AOA and NOB demonstrated enhanced and irreversible SMM removal efficiency compared to AOA alone. Furthermore, the presence of NOB altered the SMM biotransformation of AOA by metabolizing TP202 differently, possibly resulting from reduced nitrite accumulation. This study offers novel insights into the potential application of nitrifying communities for the removal of sulfonamide antibiotics (SAs) in engineered ecosystems.

Research on the negative effect of product scarcity appeals on the purchase intention of green products and its mechanism.

Studies have shown that product scarcity appeals affect consumers' perceived scarcity, willingness to pay, and other responses, and that scarcity appeal has the potential to cause consumers to pay higher attention to the product. However, there is a lack of research on the psychological responses of consumers to scarcity appeal from the perspective of perceived green washing. In this paper, three experiments are conducted to demonstrate the impact of product scarcity appeals on consumers' purchase intentions. The research shows that when green products use product scarcity appeals as a strategy, consumers' purchase intentions are affected, but consumers' information processing about the product is the most important determinant. Perceived green washing mediates the negative effect of product scarcity appeals on green product purchase intentions. And impression management motives moderate the negative effect of product scarcity appeals on green product purchase intentions. The findings of the study not only help companies to effectively adopt the right advertising strategies to improve their marketing effectiveness, but also help them to explore the market for green products.

[Contamination Characteristics and Ecological Risk of Antibiotics in Contaminated Sites of Typical Pharmaceutical Factories in China].

To understand the contamination characteristics and ecological risk of antibiotics in contaminated fields of pharmaceutical plants， samples of the surface soil， soil column， wastewater treatment process water， ground water， and residue dregs were collected from two typical antibiotic pharmaceutical plants in South and North China. A total of 87 commonly used antibiotics were quantified using ultrasound extraction-solid phase extraction and ultra-high performance liquid chromatography-mass spectrometry. The results showed that a total of 31 antibiotics of five classes were detected in all types of samples， and the maximum concentrations at each sampling point in the surface soil， soil column， residue dregs， wastewater treatment process water， and groundwater were 420 ng·g-1， 595 ng·g-1， 139 ng·g-1， 1 151 ng·L-1， and 6.65 ng·L-1， respectively. Most of the antibiotics were found in the surface soil， showing a decreasing trend with the depth of the soil column. The ecological risk assessment indicated that sulfamethazine， sulfaquinoxaline， tetracycline， chlorotetracycline， and D-sorbitol were at higher risk. Improving the efficiency of antibiotic removal from pharmaceutical wastewater and preventing production shop leaks are effective measures of controlling antibiotic contamination into and around fields in pharmaceutical plants.

Metagenomic investigation of antibiotic resistance genes and resistant bacteria contamination in pharmaceutical plant sites in China.

Pharmaceutical plant sites play a significant role in the dissemination of antibiotic resistance genes (ARGs) into the environment. It is imperative to comprehensively monitor of ARGs across various environmental media at these sites. This study focused on three pharmaceutical plants, two located in North China and one in South China. Through metagenomic approaches, we examined the composition, mobility potential, and bacterial hosts of ARGs in diverse media such as process water, groundwater, topsoil, soil cores, and pharmaceutical fermentation residues across diverse environmental matrices, including topsoil, soil cores, process water, groundwater, and pharmaceutical fermentation residues. We identified a wide array of ARGs, comprising 21 types and 740 subtypes, with process water exhibiting the highest abundance and diversity. Treatment processes varied in their efficacy in eliminating ARGs, and the clinically relevant ARGs should also be considered when evaluating wastewater treatment plant efficiency. Geographical distinctions in groundwater ARG distribution between northern and southern regions were observed. Soil samples from the three sites showed minimal impact from pharmaceutical activity, with vancomycin-resistance genes being the most prevalent. High levels of ARGs in pharmaceutical fermentation residues underscore the necessity for improved waste management practices. Metagenomic assembly revealed that plasmid-mediated ARGs were more abundant than chromosome-mediated ARGs. Metagenome-assembled genomes (MAGs) analysis identified 166 MAGs, with 62 harboring multiple ARGs. Certain bacteria tended to carry specific types of ARGs, revealing distinct host-resistance associations. This study enhances our understanding of ARG dissemination across different environmental media within pharmaceutical plants and underscores the importance of implementing strict regulations for effluent and residue discharge to control ARG spread.

Copper stress shapes the dynamic behavior of amoebae and their associated bacteria.

Amoeba-bacteria interactions are prevalent in both natural ecosystems and engineered environments. Amoebae, as essential consumers, hold significant ecological importance within ecosystems. Besides, they can establish stable symbiotic associations with bacteria. Copper plays a critical role in amoeba predation by either killing or restricting the growth of ingested bacteria in phagosomes. However, certain symbiotic bacteria have evolved mechanisms to persist within the phagosomal vacuole, evading antimicrobial defenses. Despite these insights, the impact of copper on the symbiotic relationships between amoebae and bacteria remains poorly understood. In this study, we investigated the effects of copper stress on amoebae and their symbiotic relationships with bacteria. Our findings revealed that elevated copper concentration adversely affected amoeba growth and altered cellular fate. Symbiont type significantly influenced the responses of the symbiotic relationships to copper stress. Beneficial symbionts maintained stability under copper stress, but parasitic symbionts exhibited enhanced colonization of amoebae. Furthermore, copper stress favored the transition of symbiotic relationships between amoebae and beneficial symbionts toward the host's benefit. Conversely, the pathogenic effects of parasitic symbionts on hosts were exacerbated under copper stress. This study sheds light on the intricate response mechanisms of soil amoebae and amoeba-bacteria symbiotic systems to copper stress, providing new insights into symbiotic dynamics under abiotic factors. Additionally, the results underscore the potential risks of copper accumulation in the environment for pathogen transmission and biosafety.

Antibacterial polylactic acid fabricated via Pickering emulsion approach with polyethyleneimine and polydopamine modified cellulose nanocrystals as emulsion stabilizers.

Antibacterial biodegradable plastics are highly demanded for food package and disposable medical plastic consumables. Incorporating antibacterial nanoagents into polymer matrices is an effective method to endow polymers with antibacterial activity. However, synthesis of sustainable antibacterial nanoagents with high antibacterial activity via facile approach and well dispersion of them in polymer matrices are still challenging. In this study, polyethyleneimine (PEI) was grafted on surface of cellulose nanocrystals (CNCs) via the oxidation self-polymerization of dopamine (DA) and the Michael addition/Schiff base reaction between DA and PEI. The resulted PEI and polydopamine modified CNCs (PPCs) showed substantially enhanced antibacterial activity and reduced cytotoxicity for NIH3T3 than PEI due to increased local concentration and anchoring of PEI. The minimum concentration of PPCs to achieve antibacterial rate of 99.99 % against S. aureus and E. coli were about 50 and 20 µg/mL, respectively. PPCs displayed outstanding emulsifying ability, and PPC coated polylactic acid (PLA) microspheres were obtained by drying PPC stabilized PLA Pickering emulsion, leading to a well dispersion of PPCs in PLA. PPC/PLA film prepared by hot-pressing displayed great antibacterial performance and enhanced mechanical properties. Therefore, this study proposed a facile approach to fabricate biocompatible antibacterial nanoagents and plastics.

Biotransformation of sulfamonomethoxine in a granular sludge system: Pathways and mechanisms.

The biotransformation of sulfamonomethoxine (SMM) was studied in an aerobic granular sludge (AGS) system to understand the role of sorption by microbial cells and extracellular polymeric substances (EPS) and the role of functional microbe/enzyme biodegradation. Biodegradation played a more important role than adsorption, while microbial cells covered with tightly bound EPS (TB-EPS) showed higher adsorption capacity than microbial cells themselves or microbial cells covered with both loosely bound EPS (LB-EPS) and TB-EPS. The binding tests between EPS and SMM and the spectroscopic analyses (3D-EEM, UV-Vis, and FTIR) were performed to obtain more information about the adsorption process. The data showed that SMM could interact with EPS by combining with aromatic protein compounds, fulvic acid-like substances, protein amide II, and nucleic acids. Batch tests with various substances showed that SMM removal rates were in an order of NH2OH (60.43 ± 2.21 µg/g SS) > NH4Cl (52.96 ± 0.30 µg/g SS) > NaNO3 (31.88 ± 1.20 µg/g SS) > NaNO2 (21.80 ± 0.42 µg/g SS). Hydroxylamine and hydroxylamine oxidoreductase (HAO) favored SMM biotransformation and the hydroxylamine-mediated biotransformation of SMM was more effective than others. In addition, both ammonia monooxygenase (AMO) and CYP450 were able to co-metabolize SMM. Analysis of UPLC-QTOF-MS indicated the biotransformation mechanisms, revealing that acetylation of arylamine, glucuronidation of sulfonamide, deamination, SO2 extrusion, and δ cleavage were the five major transformation pathways. The detection of TP202 in the hydroxylamine-fed Group C indicated a new biotransformation pathway through HAO. This study contributes to a better understanding of the biotransformation of SMM.

Evolution of extracellular polymeric substances (EPS) in aerobic sludge granulation: Composition, adherence and viscoelastic properties.

Aerobic granular sludge (AGS) is a promising wastewater treatment innovation, but its instability hinders its broader applications. Understanding the granulation process is vital to address this issue. Extracellular polymeric substances (EPS) play an essential role in sludge granulation. However, one crucial aspect of EPS, the adhesive and viscoelastic properties, has been neglected in AGS studies. In this study, we set up two reactors fed with COD/N ratios of 100: 5 (R1) and 100: 10 (R2) for comparison, to investigate the adhesive and viscoelastic properties of sludge EPS during the sludge granulation. We found that R2 showed a more rapid sludge granulation with more stable granules formed, contained a higher abundance of amoA gene, and had a higher production of polysaccharides than R1. We also found a sharp decrease in polysaccharide production and ß-sheets abundance accompanied by granule size decrease in R1 on Day 80, indicating their essential roles in sludge granulation and granule stability. QCM-D (quartz crystal microbalance with dissipation monitoring) results showed that EPS became less adhesive and inclined to form unstable layers on the mineral surfaces along with the sludge granulation process. In contrast, they showed the opposite behavior and became more adhesive on the PVDF sensors. Our results suggested that higher polysaccharides, a higher ß-sheets band in proteins, and lower mineral surface-adhesive and viscoelastic properties benefited the aerobic sludge granulation process and the granule maintenance.

Responses of aerobic granular sludge to fluoroquinolones: Microbial community variations, and antibiotic resistance genes.

In this study, aerobic granular sludge (AGS) was operated under high levels of ammonium for removing three fluoroquinolones (FQs), i.e., ciprofloxacin (CFX), ofloxacin (OFX), and norfloxacin (NFX) at 3, 300, and 900 µg/L, respectively. Two key objectives were to investigate the differential distribution of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in sludge fractions and to evaluate correlations between ARGs and MGEs to nitrifying and denitrifying bacteria. AGS showed excellent stability under the exposure of FQs, with nitrite-oxidizing bacteria (NOB) more sensitive to FQs than ammonium-oxidizing bacteria (AOB). Specific oxygen utilization rates (SOUR) showed a reduction of 26.9% for NOB but only 4.0% of the reduced activity of AOB by 3 µg/L FQs. AGS performed better removal efficiencies for CFX and NFX than OFX, and the efficiencies increased with their elevated concentrations, except at 900 µg/L FQs. The elevated FQ concentrations led to a significant enrichment of intI1 and genus Thauera, while qnrD and qnrS showed no accumulation. Compared to nitrifiers, FQs relevant ARGs and the intI1 gene preferred to exist in denitrifiers, and the abundance of denitrifiers behaved a decreasing trend with the sludge size. Two quinoline-degrading bacteria were found in the AGS system, i.e., Alicycliphilus and Brevundimonas, possibly carrying qnrS and qnrD, respectively. Their relative abundance increased with the sludge size, which was 2.18% in sludge <0.5 mm and increased to 3.70% in sludge >2.0 mm, suggesting that the AGS may be a good choice in treating FQs-containing wastewater.

The influence of extracellular polymeric substances on the coagulation process of cyanobacteria.

The hydrophobicity and flocculation properties of cyanobacterial cells are closely related to their extracellular polymeric substances (EPS). During the treatment of drinking water, the coagulation and removal of EPS-wrapped cyanobacterial particles from natural water sources is very difficult. In this work, a series of surface characteristics of cyanobacterial cells with different EPS fractions were analyzed to evaluate their influences on the coagulation process. With the removal of EPS, the coagulation efficiency of cyanobacteria was gradually improved. The intracellular microcystin release showed that the cyanobacterial cells in each EPS removal phase were almost intact with few broken cells. The surface of cyanobacterial cells had higher hydrophobicity and lower zeta potentials with each step of the EPS extraction, which improved the ratio of particles that were in an unstable state. Furthermore, the deeper the EPS extraction phase, the larger the decreased in size of cyanobacterial particles, thus increasing their specific surface area for adsorption with coagulant. It was concluded that the coagulation mechanism of EPS-wrapped cyanobacterial particles was: the cyanobacterial cells were first peeled off through attraction by opposite charges from the coagulant, and then they were adsorbed before settling down. This study provides a scientific basis for the removal of cyanobacteria by enhancing coagulation.

Untreated swine wastes changed antibiotic resistance and microbial community in the soils and impacted abundances of antibiotic resistance genes in the vegetables.

Animal waste fertilization is a traditional agricultural practice, which may have adverse effects to soil ecosystem. However, the side-effects of animal waste fertilization on vegetables are less studied. Here we selected a swine farming village for investigation with a nearby village without swine farming as comparison. In the swine farming village, the farmers use untreated swine manure and wastewater as fertilizers for vegetable cultivation. In the reference village, the farmers mainly use commercial organic fertilizers. The objective of this study is to assess the impacts of untreated swine waste fertilization on both soils and vegetables in terms of antibiotics, antibiotic resistance genes (ARGs) and bacterial microbial communities. The results indicate that untreated swine waste fertilization caused both antibiotic and ARG contaminations and changed the microbial community compositions in the soils. Varieties of tetracyclines and related resistance genes were detected especially in swine wastewater treated soils. The soil quality was impacted with the relations to bacterial abundances and microbial geochemical functions. Proteobacteria and Bacteroidetes were prevalent and positively correlated to ARGs in soils, indicating they were potential antibiotic resistant bacteria. Antibiotics and ARGs were detected in vegetables of both villages. The abundances of ARGs were relatively higher in some vegetable samples of the swine farming village than the reference village. In addition, intracellular parasites Rickettsiales with positive correlation to ARGs were prevalent in some vegetables of swine farming village, indicating potential health risks through eating contaminated vegetables. The results of this study suggest that untreated swine wastes may cause adverse effects to not only agricultural soils but also associated vegetables.

[Contamination Characteristics and Ecological Risk Assessment of Androgens, Glucocorticoids, and Progesterone in the Liusha Bay, South China Sea].

Steroid hormones have been continuously detected and well studied in freshwater bodies in recent years, although information regarding their contamination characteristics in seawater is rare. In this paper, samples were collected in Liusha Bay, South China Sea, and the contamination characteristics, as well as the spatial distribution of 33 steroid hormones, were studied by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The results showed that 7 steroid hormones occurred with concentrations ranging from 0.003 (medroxyprogesterone, MP) to 9.023 ng·L-1(dehydroprogesterone, DGT), and from 0.017 (androsta-1,4-diene-3,17-dione, ADD) to 9.281 ng·g-1 (4-androstene-3,17-dione, AED) in seawater and sediment samples, respectively. The concentrations of detected steroid hormones were higher during wet weather than during the dry weather, and higher in the aquaculture area compared to that in the non-aquaculture area. There were no significant differences in the spatial and temporal distribution of steroid hormones in sediment. Wastewater discharge and additives in aquaculture feeds were the main routes of steroid hormones entering the marine environment. The results of the ecological risk assessment indicated that the AED posed low risk to the marine environment, whereas other steroid hormones posed no risk. Correlation analysis indicated that the concentration distribution of steroid hormones was related to salinity, water temperature, particulate matter (SS), and chemical oxygen demand (COD) in the marine environment. The results of this study contribute to the understanding of the contamination characteristics of steroid hormones in the Liusha Bay area and provide a scientific basis for ecological risk assessment and control.

Optimization of moving bed biofilm reactors for oil sands process-affected water treatment: The effect of HRT and ammonia concentrations.

Two moving bed biofilm reactors (MBBRs) were optimized to improve the biodegradation of organic compounds in raw and ozonated OSPW by changing the hydraulic retention time (HRT) and the influent ammonia concentrations. During the five stages, the average COD removal reached 50.8±3.4%, 52.8±6.5%, 54.7±4.3%, 56.3±2.2%, and 58.0±2.3% respectively in raw OSPW MBBR, and 54.6±3.8%, 57.2±7.1%, 55.5±5.8%, 58.3±2.2%, and 60.7±2.3% respectively in ozonated OSPW MBBR. Welch's weighted ANOVA tests show that the increase in ammonia levels significantly improved the COD removal in the two systems, while the HRT was an important parameter for COD decrease in the raw OSPW MBBR. Compared to the HRT, the increase in ammonia concentrations were more beneficial for acid extractable fraction (AEF) degradation and the average AEF removal reached 29.80% (raw OSPW MBBR) and 16.50% (ozonated OSPW MBBR) by the end of the optimization (Stage V; HRT=96h, 60mg/L NH4+-N). >98% of the NH4+-N was removed in the two MBBR systems, showing good nitrification. Microtoxicity tests showed that no significant correlations were found between HRT/ammonia levels and the OSPW toxicity changes toward V. fischeri. Spearman's rank correlation analysis was applied for q-PCR data, showing that positive correlations between the removal efficiencies of AEF and NSR and NirK gene copies were observed in the raw OSPW MBBR system, while positive correlations between AEF removal efficiency and total bacteria gene, NSR, Nitro, and NirK gene copies were observed in the ozonated OSPW MBBR system.

Comparison of biomass from integrated fixed-film activated sludge (IFAS), moving bed biofilm reactor (MBBR) and membrane bioreactor (MBR) treating recalcitrant organics: Importance of attached biomass.

This study compared microbial characteristics and oil sands process-affected water (OSPW) treatment performance of five types of microbial biomass (MBBR-biofilm, IFAS-biofilm, IFAS-floc, MBR-aerobic-floc, and MBR-anoxic-floc) cultivated from three types of bioreactors (MBBR, IFAS, and MBR) in batch experiments. Chemical oxygen demand (COD), ammonium, acid extractable fraction (AEF), and naphthenic acids (NAs) removals efficiencies were distinctly different between suspended and attached bacterial aggregates and between aerobic and anoxic suspended flocs. MBR-aerobic-floc and MBR-anoxic-floc demonstrated COD removal efficiencies higher than microbial aggregates obtained from MBBR and IFAS, MBBR and IFAS biofilm had higher AEF removal efficiencies than those obtained using flocs. MBBR-biofilm demonstrated the most efficient NAs removal from OSPW. NAs degradation efficiency was highly dependent on the carbon number and NA cyclization number according to UPLC/HRMS analysis. Mono- and di-oxidized NAs were the dominant oxy-NA species in OSPW samples. Microbial analysis with quantitative polymerase chain reaction (q-PCR) indicated that the bacterial 16S rRNA gene abundance was significantly higher in the batch bioreactors with suspended flocs than in those with biofilm, the NSR gene abundance in the MBR-anoxic bioreactor was significantly lower than that in aerobic batch bioreactors, and denitrifiers were more abundant in the suspended phase of the activated sludge flocs.

Microbial activity balance in size fractionated suspended growth biomass from full-scale sidestream combined nitritation-anammox reactors.

The purpose of this study was to determine the abundance, distribution and activity of aerobic ammonia-oxidizing bacteria (AOB) and anammox in size fractionated aggregates from full-scale suspended growth combined nitritation-anammox sidestream reactors. Plants with or without a cyclone device were also studied to assess a purported enrichment of anammox granules. Specific aerobic ammonium oxidation rates (p=0.01) and specific oxygen uptake rates (p=0.02) were significantly greater in flocs than in granules. AOB abundance measured using quantitative FISH was significantly higher in flocs than in granules (p=0.01). Conversely, anammox abundance was significantly greater in granules (p=0.03). The average ratio of anammox/AOB in systems employing hydrocyclone separation devices was 2.4, significantly higher (p=0.02) than the average ratio (0.5) in a system without a hydrocyclone. Our results demonstrate substantial functional and population-level segregation between floccular and granular fractions, and provide a key corroboration that cyclone separation devices can increase anammox levels in such systems.

Treatment of oil sands process-affected water (OSPW) using ozonation combined with integrated fixed-film activated sludge (IFAS).

Two integrated fixed-film activated sludge (IFAS) reactors were operated continuously to treat raw (untreated) and ozonated (30 mg/L) oil sands process-affected water (OSPW). After 11 months, 12.1% of the acid extractable fraction (AEF) and 43.1% of the parent naphthenic acids (NAs) were removed in the raw OSPW IFAS, while 42.0% AEF and 80.2% of parent NAs were removed in the ozonated OSPW IFAS. UPLC/HRMS analysis showed that NA biodegradation significantly decreased as the NA cyclization number increased. Confocal laser scanning microscopy (CLSM) results showed that the biofilm in the ozonated OSPW IFAS was significantly thicker (94 ± 1.6 µm) than the biofilm in the raw OSPW IFAS (72 ± 2.8 µm) after 283 days of cultivation. The quantitative polymerase chain reaction (q-PCR) revealed that the abundance proportions of both nitrifier genes (AomA, NSR and Nitro) and denitrifier genes (narG, nirS, nirK and nosZ) within total bacteria were significantly higher in biofilms than in flocs in the raw OSPW IFAS system, but a different trend was observed in the ozonated OSPW IFAS system.

Treatment of oil sands process-affected water using moving bed biofilm reactors: With and without ozone pretreatment.

Two moving bed biofilm reactors (MBBRs) were operated to treat raw (untreated) and 30 mg/L ozone-treated oil sands process-affected water (OSPW). After 210 days, the MBBR process showed 18.3% of acid-extractable fraction (AEF) and 34.8% of naphthenic acids (NAs) removal, while the ozonation combined MBBR process showed higher removal of AEF (41.0%) and NAs (78.8%). Biodegradation of raw and ozone treated OSPW showed similar performance. UPLC/HRMS analysis showed a highest NAs removal efficiency with a carbon number of 14 and a -Z number of 4. Confocal laser scanning microscopy (CLSM) showed thicker biofilms in the raw OSPW MBBR (97 ± 5 µm) than in the ozonated OSPW MBBR (71 ± 12 µm). Quantitative polymerase chain reaction (q-PCR) results showed higher abundance of gene copies of total bacteria and nitrogen removal relevant bacteria in the ozonated OSPW MBBR, but no significant difference was found. MiSeq sequencing showed Proteobacteria, Nitrospirae, and Acidobacteria were dominant.

Characterization of the interactions between tetracycline antibiotics and microbial extracellular polymeric substances with spectroscopic approaches.

The antibiotics have attracted global attentions for their impact on aquatic ecosystem. The knowledge about the fate of antibiotics encountering extracellular polymeric substances (EPS) is, however, limited. In this study, we investigated the interacting mechanisms of tetracycline (TC) to EPS extracted from aerobic activated sludge. The contributions of the main components of EPS, extracellular proteins, and polysaccharides were evaluated using bovine serum albumin and alginate sodium, respectively. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance indicated that hydroxyl, carboxyl, and amino groups were the domain chemical groups involved in the interaction between TC and EPS, and the binding of TC onto EPS changed the structure of these chemical groups, thus causing shifts in their UV-visible absorption spectra. In addition, we found that extracellular proteins, rather than polysaccharides, were the major active contents involved in the interaction. Three-dimensional excitation-emission matrix fluorescence spectroscopy showed that the fluorophores in EPS were clearly quenched by TC and the static quenching process was observed, implying the complex formation of TC and EPS. Furthermore, thermodynamic analysis indicated that the binding of TC with EPS is spontaneous and dominated by electrostatic forces.