Effects of DNA Damage and Oxidative Stress in Human Bronchial Epithelial Cells Exposed to PM2.5 from Beijing, China, in Winter.

Epidemiological studies have corroborated that respiratory diseases, including lung cancer, are related to fine particulate matter (<2.5 µm) (PM2.5) exposure. The toxic responses of PM2.5 are greatly influenced by the source of PM2.5. However, the effects of PM2.5 from Beijing on bronchial genotoxicity are scarce. In the present study, PM2.5 from Beijing was sampled and applied in vitro to investigate its genotoxicity and the mechanisms behind it. Human bronchial epithelial cells 16HBE were used as a model for exposure. Low (67.5 µg/mL), medium (116.9 µg/mL), and high (202.5 µg/mL) doses of PM2.5 were used for cell exposure. After PM2.5 exposure, cell viability, oxidative stress markers, DNA (deoxyribonucleic acid) strand breaks, 8-OH-dG levels, micronuclei formation, and DNA repair gene expression were measured. The results showed that PM2.5 significantly induced cytotoxicity in 16HBE. Moreover, the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and cellular heme oxygenase (HO-1) were increased, and the level of glutathione (GSH) was decreased, which represented the occurrence of severe oxidative stress in 16HBE. The micronucleus rate was elevated, and DNA damage occurred as indicators of the comet assay, γ-H2AX and 8-OH-dG, were markedly enhanced by PM2.5, accompanied by the influence of 8-oxoguanine DNA glycosylase (OGG1), X-ray repair cross-complementing gene 1 (XRCC1), and poly (ADP-ribose) polymerase-1 (PARP1) expression. These results support the significant role of PM2.5 genotoxicity in 16HBE cells, which may occur through the combined effect on oxidative stress and the influence of DNA repair genes.

Elimination of antibiotic resistance genes in waste activated sludge by persulfate treatment during the process of sludge dewatering.

Two sludge conditioning modes (nanoscale zero valent iron modified by Ginkgo biloba L. leaf (G-nZVI)/sodium persulfate (PS) conditioning with different ratios (1:0, 1:0.1, 1:1 and 1:10) and G-nZVI/PS conditioning with continuous addition) in reducing the specific resistance of filtration (SRF) and removing antibiotic resistant genes (ARGs) were investigated. After 3 min, the SRF values decreased in following order: 2.45 × 108 m/kg (1:10) > 5.95 × 106 m/kg (1:0.1) > 3.72 × 106 m/kg (1:0) > 4.92 × 105 m/kg (1:1). In the continuous addition (1:1), the SRF value decreased from 1.04 × 108 m/kg to 6.47 × 106 m/kg at 9 min. Removal efficiency of ARGs was 2-6 orders of magnitude and no regeneration of ARGs was observed in sludge and water phase. When treated samples were incubated for 36 h, dominant microflora was negatively correlated with ARGs. This study revealed persulfate treatment could achieve dewatering and remove ARGs, simultaneously.

Sulfidated nanoscale zero-valent iron is an efficient material for the removal and regrowth inhibition of antibiotic resistance genes.

Antibiotic resistance genes (ARGs) and mobile gene elements (MGEs), the emerging genetic contaminants, are regarded as severe risks to public health for impairing the inactivation efficacy of antibiotics. Secondary effluents from wastewater treatment plants are the hotspots for spreading these menaces. Herein, sulfidated nanoscale zero-valent iron (S-nZVI) was occupied to remove ARGs and MGEs in secondary effluents and weaken the regrowth capacity of their bacterial carriers. The effects of S/Fe molar ratios (S/Fe), initial pH and dosages on 16S rRNA and ARGs removal were also investigated. Characterization, mass balance and scavenging experiments were conducted to explore the mechanisms of the gene removal. Quantitative PCR (qPCR) and high throughput fluorescence qPCR showed more than 3 log unit of 16S rRNA and seven out of 10 ARGs existed in secondary effluent could be removed after S-nZVI treatment. The mechanisms might be that DNA accepted the electron provided by the Fe0 core of S-nZVI after being adsorbed onto S-nZVI surface, causing the decrease of 16S rRNA, ARGs and lost their regrowth capacity, especially for typical MGE (intI1) and further inhibiting the vertical gene transfer (VGT) and intI1-induced horizontal gene transfer (HGT). Fe0 core was oxidized to iron oxides and hydroxides at the same time. High throughput sequencing, network analysis and variation partitioning analysis revealed the complex correlations between bacteria and ARGs in secondary effluent, S/Fe could directly influence ARGs variations, and bacterial genera made the greatest contribution to ARGs variations, followed by MGEs and operational parameters. As a result, S-nZVI could be an available reductive approach to deal with bacteria and ARGs.

Emergence and spread patterns of antibiotic resistance genes during two different aerobic granular sludge cultivation processes.

The prevalence and accumulation of antibiotic resistance genes (ARGs) were frequently detected in biological wastewater treatment processes, which might cause potential health crisis to human. In present study, the fates of ARGs during two different aerobic granular sludge (AGS) cultivation processes were investigated. The results showed that traditional AGS (T-AGS) cultivation process and enhanced AGS (E-AGS) cultivation process had significant differences (P < 0.005) in ARGs shift patterns. E-AGS process had higher average relative abundance (0.280 ± 0.079) of ARGs than T-AGS process (0.130 ± 0.041), while the intensity of ARGs enrichment during E-AGS (1.52-5.29 fold) was lower than T-AGS (3.79-75.31 fold) process. TnpA and intI1 as two different types of mobile genetic elements (MGEs) carrying ARGs, were observed to contribute significantly to the horizontal gene transfer (HGT) during T-AGS (r = 0.902, P < 0.050) and E-AGS (r = 0.823, P < 0.001) processes, respectively. Higher HGT level took place and more possible potential hosts (25 hosts) harboring ARGs were detected during E-AGS process comparing with T-AGS process (17 hosts). Meanwhile, over large AGS might increase the propagation of several antibiotic deactivation ARGs, so it was not advised. Overall, whether during T-AGS or during E-AGS process which was applied in a pilot-scale sequencing batch reactor treating municipal wastewater, the accumulation and spread of ARGs were inevitable. It should be valued that some suitable pre-treatments of seed sludge should be executed, meanwhile, advanced treatment for removing of ARGs in AGS should be conducted to maintain the relative abundances of ARGs at relatively low level.

DNA-based stable isotope probing identifies triclosan degraders in nitrification systems under different surfactants.

Three widely-used surfactants, rhamnolipid (RL), sophorolipid (SL) and sodium dodecyl benzene sulfonate (SDBS), were chosen to investigate their effects on the nitrification systems treating step-wised triclosan (TCS). Surfactants had little effects on nitrification. Surfactants could promote the desorption of TCS and enhance the TCS biodegradation in nitrification systems. And TCS biodegradation efficiencies obtained with RL, SL and SDBS were 1.25, 1.23 and 1.14 times higher than the control with 9.0 mg/L TCS, respectively. Illumina MiSeq sequencing showed that Amaricoccus could be resistant to TCS. And Amaricoccus, detected with RL, SL and SDBS, were more abundant than the control. DNA-based stable isotope probing assays revealed Amaricoccus was the major TCS degrader. And the addition of surfactants could obviously increase the diversity of active TCS degraders, especially for biosurfactants. It seems that the addition of surfactants showed positive effects for the nitrification systems treating TCS wastewater.

Enhanced granulation process, a more effective way of aerobic granular sludge cultivation in pilot-scale application comparing to normal granulation process: From the perspective of microbial insights.

Aerobic granular sludge (AGS) could be cultivated from only flocs (called normal granulation (NG) process) or mixture of flocs and crushed AGS (called enhanced granulation (EG) process), which might lead to different system performances such as granulation speed and pollutants removal efficiencies. However, the differences of mechanisms between NG and EG processes at microbial community level are still unknown. In this study, the NG and EG processes were implemented successively in a pilot-scale sequencing batch reactor (SBR) with certain amounts of additional carbon sources. Illumina MiSeq sequencing and quantitative PCR were applied to investigate the dynamics of bacterial communities during NG and EG processes and explore the possible explanations for faster EG process. The results showed that significant distinctions in bacterial diversities and community structures were observed between NG and EG processes. The major contributor to NG process was bacterial communities with 32.04% contribution. While EG process was more dependent on the interactions (73.16% contribution) between the bacterial communities and environmental variables (operational parameters and self-adaptive variable). EG process had higher relative abundances of functional bacteria than NG process. Glycogen accumulating organisms (GAOs) related bacteria with a total relative abundance of maximum 65.43% might be mainly responsible for the faster EG process. This study provided microbial insights for practical application of AGS technology that inoculating crushed AGS might be an effective way to cultivate AGS.

The dominance of non-halophilic archaea in autotrophic ammonia oxidation of activated sludge under salt stress: A DNA-based stable isotope probing study.

Dynamics of nitrification activity, ammonia-oxidizing archaea (AOA) and bacteria (AOB) abundance and active ammonia oxidizers of activated sludge were explored under different salinities. Results showed that specific ammonium oxidation rates were significantly negative with increasing salinity. The responses of AOA and AOB populations to salt stress were distinct. AOA abundance decreased at moderate salinities (2.5, 5 and 7 g L-1) and increased at high salinities (10, 15, 20 and 30 g L-1), while AOB abundance showed opposite tendency. DNA-based stable isotope probing assays indicated AOA exclusively dominated active ammonia oxidation of test samples under different salinities. The active AOA communities retrieved were all non-halophilic and regulated by salinities. Candidatus Nitrosocosmicus exaquare and Ca. Nitrosocosmicus franklandus were the predominantly active AOA in both salt-free and salt-containing microcosms, while 13C-labeled Nitrososphaera viennensis and Ca. Nitrososphaera gargensis were only retrieved from the microcosms amended with 0 and 30 g L-1 salinity, respectively.

More obvious air pollution impacts on variations in bacteria than fungi and their co-occurrences with ammonia-oxidizing microorganisms in PM2.5.

Based on long-term systematic sampling, information is currently limited regarding the impacts of different air pollution levels on variations of bacteria, fungi and ammonia-oxidizing microorganisms (AOMs) in fine particulate matter (PM2.5), especially their interactions. Here, PM2.5 samples were weekly collected at different air pollution levels in Beijing, China during one-year period. Microbial composition was profiled using Illumina sequencing, and their interactions were further investigated to reveal the hub genera with network analysis. Diversity of bacteria and fungi showed obvious seasonal variations, and the heavy- or severe-pollution levels mainly affected the diversity and composition of bacteria, but not fungi. While, the community structure of both bacteria and fungi was influenced by the combination of air pollution levels and seasons. The most abundant bacterial genera and some genera with highest abundance in heavy- or severe-pollution days were the hub bacteria in PM2.5. Whereas, only the dominant fungi in light-pollution days in winter were the hub fungi in PM2.5. The complex positive correlations of bacterial or fungal pathogens would aggravate the air pollution effects on human health, despite of their low relative abundances. Moreover, the strong co-occurrence and co-exclusion patterns of bacteria and fungi in PM2.5 were identified. Furthermore, the hub environmental factors (e.g., relative humidity and atmospheric pressure) may play central roles in the distributions of bacteria and fungi, including pathogens. Importantly, AOMs showed significant co-occurrence patterns with the main bacterial and fungal genera and potential pathogens, providing possible microbiological evidences for controlling ammonia emissions to effectively reduce PM2.5 pollution. These results highlighted the more obvious air pollution impacts on bacteria than fungi, and the complex bacterial-fungal interactions, as well as the important roles of AOMs in airborne microbial interactions webs, improving our understanding of bioaerosols in PM2.5.

Effects of triclosan on performance, microbial community and antibiotic resistance genes during partial denitrification in a sequencing moving bed biofilm reactor.

Effects of triclosan (TCS) on performance, microbial community and antibiotic resistance genes (ARGs) during partial denitrification (PD) were investigated in a sequencing moving bed biofilm reactor (SMBBR). TCS inhibited nitrite accumulation; inhibition effect was more obvious as TCS concentration increased from 1 to 5 mg/L, but it could recover. Extracellular polymeric substances contents increased with 1 mg/L TCS addition and decreased a lot at 5 mg/L TCS. Community structure in biofilm was different from that in floccular sludge, but it was similar at 5 mg/L TCS. Illumina sequencing showed that Pseudomonas, Aeromonas, Shewanella and Thauera became dominant genera. Abundance of nirS was stable and higher than that of narG and nosZ. High-throughput qPCR showed that mexF, acrA-02, fabK, etc. were screened at 5 mg/L TCS. IntI1 and tnpA-04 were abundant mobile genetic elements. The study furthers understanding of effects of TCS on PD, bacterial communities and ARGs in SMBBR.

Simultaneous adsorption and degradation of triclosan by Ginkgo biloba L. stabilized Fe/Co bimetallic nanoparticles.

Triclosan (TCS), an antimicrobial agent added in many pharmaceutical and personal care products, can cause some environmental problems due to its bioaccumulation, toxicity and potential antibiotic cross-resistance. In this study, Ginkgo biloba L. leaf extract was used as the green stabilizing agent to synthesize Fe/Co bimetallic nanoparticles (G-Fe/Co NPs), which were applied to remove TCS from aqueous solution. G-Fe/Co NPs were characterized by TEM, EDS, SEM, BET, FTIR, XRD and XPS. G. biloba L. leaf extract improved the dispersion and reduced the passivation of NPs. The TCS removal efficiency followed the order of G-Fe/Co NPs > G-Fe NPs > Co NPs > Fe/Co NPs > Fe NPs. G-Fe/Co NPs can be reused at least eight times. The Co leaching under different initial pH values was negligible. The factors affecting the TCS removal were investigated. The results indicated that the removal of TCS followed pseudo-second-order kinetics, and the removal rate constant decreased with increasing the initial pH value and the initial TCS concentration, and decreasing the Co loading of G-Fe/Co NPs and NPs dosage. The mass balance of TCS removal by G-Fe/Co NPs indicated that adsorption was dominant process and TCS degradation was an accumulative process.

The more important role of archaea than bacteria in nitrification of wastewater treatment plants in cold season despite their numerical relationships.

Nitrification failure of wastewater treatment plants (WWTPs) in cold season calls into investigations of the functional ammonia-oxidizing microorganisms (AOMs). In this study, we report the abundance of ammonia-oxidizing archaea (AOA), bacteria (AOB) and complete ammonia-oxidizing (comammox) Nitrospira in 23 municipal WWTPs in cold season, and explore the correlations between AOMs abundance and their relative contribution to nitrification. The copy numbers of AOA and AOB amoA gene ranged from 2.42 × 107 to 2.47 × 109 and 5.54 × 106 to 3.31 × 109 copies/g sludge, respectively. The abundance of amoA gene of Candidatus Nitrospira inopinata, an important strain of comammox Nitrospira, was stable with averaged abundance of 8.47 × 106 copies/g sludge. DNA-based stable isotope probing (DNA-SIP) assays were conducted with three typical WWTPs in which the abundance of AOA was lower than, similar to and higher than that of AOB, respectively. The results showed that considerable 13C-assimilation by AOA was detected during active nitrification in all WWTPs, whereas just a much lesser extent of 13C-incorporation by AOB and comammox Nitrospira was found in one WWTP. High-throughput sequencing with 13C-labeled DNA also showed the higher reads abundance of AOA than AOB and comammox Nitrospira. Nitrososphaera viennensis was the dominant active AOA, while Nitrosomonas oligotropha and Nitrosomonas europaea were identified as active AOB. The results obtained suggest that AOA, rather than AOB and comammox Nitrospira, dominate ammonia oxidation in WWTPs in cold season despite the numerical relationships of AOMs.

Functional genera, potential pathogens and predicted antibiotic resistance genes in 16 full-scale wastewater treatment plants treating different types of wastewater.

This study aimed to investigate the bacterial communities and antibiotic resistance genes (ARGs) in 16 wastewater treatment plants (WWTPs) treating municipal, industrial and mixed wastewater. Wastewater types showed obvious effects on bacterial communities and functions. Nitrosomonas, Nitrospira, Hyphomicrobium and Accumulibacter were the main functional genera. Mycobacterium was the dominant potential pathogens. A total of 69 ARGs were obtained, and the dominant ARGs subtypes were similar in different WWTPs. Efflux pumps were the most common resistance mechanisms. Copper and zinc resistance genes were the main metal resistance genes (MRGs). Wastewater types affected the distributions of ARGs and MRGs, and they were more similar in industrial and mixed wastewater. The co-occurrence of ARGs existed within or across ARG types, and they were also positively linked to MRGs, some functional and pathogenic genera or environmental factors. This study furthers the understanding of interactions between bacterial communities, ARGs and MRGs in different WWTPs.

[Shovel-shaped electrode transurethral plasmakinetic enucleation versus plasmakinetic resection of the prostate in the treatment of benign prostatic hyperplasia].

OBJECTIVE: To compare the safety and effectiveness of shovel-shaped electrode transurethral plasmakinetic enucleation of the prostate (PKEP) with those of plasmakinetic resection of the prostate (PKRP) in the treatment of benign prostatic hyperplasia (BPH). METHODS: We retrospectively analyzed the clinical data about 78 BPH patients received in Shanghai Ninth People's Hospital from June 2016 to January 2017, 39 treated by shovel-shaped electrode PKEP and the other 39 by PKRP. We observed the patients for 6 months postoperatively and compared the effects and safety of the two surgical strategies. RESULTS: No statistically significant difference was observed between the PKEP and PKRP groups in the operation time (ï¼»69.3 ± 8.8ï¼½ vs ï¼»72.2 ± 7.9ï¼½ min, P = 0.126), but the former, as compared with the latter, showed a markedly less postoperative loss of hemoglobin (ï¼»3.9 ± 2.8ï¼½ vs ï¼»13.9 ± 5.2ï¼½ g/L, P <0.001) and shorter bladder irrigation time (ï¼»12.5 ± 1.2ï¼½ vs ï¼»43.4 ± 2.8ï¼½ h, P <0.001), catheterization time (ï¼»64.0 ± 4.5ï¼½ vs ï¼»84.8 ± 3.0ï¼½ h, P <0.001) and hospital stay (ï¼»3.1 ± 0.3ï¼½ vs ï¼»5.5 ± 0.4ï¼½ d, P <0.001). There were no statistically significant differences between the PKEP and PKRP groups in the postoperative maximum urinary flow rate (Qmax) (ï¼»21.62 ± 1.07ï¼½ vs ï¼»21.03 ± 0.96ï¼½ ml/s, P = 0.12), International Prostate Symptoms Score (IPSS) (5.85 ± 0.90 vs 6.03 ± 0.81, P = 0.279), quality of life score (QoL) (2.0 ± 0.73 vs 2.28 ± 0.72, P = 0.09), postvoid residual urine volume (PVR) (ï¼»19.59 ± 6.01ï¼½ vs ï¼»20.21 ± 5.16ï¼½ ml, P = 0.629), or the incidence rates of urinary incontinence (2.56% ï¼»1/39ï¼½ vs 7.69% ï¼»3/39ï¼½, P >0.05) and other postoperative complications. CONCLUSIONS: Both PKEP and PKRP are effective methods for the treatment of BPH, but PKEP is worthier of clinical recommendation for a better safety profile, more thorough removal of the prostate tissue, less blood loss, shorter hospital stay, and better improved quality of life of the patient.

[Microbial Community Dynamics During Two Sludge Granulation Processes].

Aerobic granular sludge (AGS) was cultivated in a sequencing batch reactor (SBR). In this study, AGS was broken during the formation process and then mature AGS formed again. The microbial community dynamics during two sludge granulation processes were investigated using high-throughput sequencing to reveal the dominant bacteria beneficial to AGS formation. The abundance dynamics of nitrifying microorganisms were analyzed by a quantitative polymerase chain reaction (qPCR). The results showed that the amount of extracellular protein and polysaccharides increased during two sludge granulation processes. The abundance of ammonia oxidizing archaea (AOA) increased during the first AGS formation process and during the process of AGS maturation. The abundance of ammonia oxidizing bacteria (AOB) decreased during the first AGS formation process, while it maintained a higher abundance than AOA during AGS cultivation. Microbial diversity decreased with AGS formation. The relative abundance of Proteobacteria increased by 12.29% and 5.90% during two sludge granulation processes, respectively. Candidatus Competibacter belonging to Proteobacteria was enriched during two sludge granulation processes, accounting for 14.20% in mature AGS. Overall, extracellular protein and polysaccharides may have contributed to the sludge granulation. Both AOA and AOB might have been involved in ammonia oxidation. This study indicated that Ca. Competibacter might contribute to AGS formation.

Ammonia-oxidizing bacteria dominate ammonia oxidation in a full-scale wastewater treatment plant revealed by DNA-based stable isotope probing.

A full-scale wastewater treatment plant (WWTP) with three separate treatment processes was selected to investigate the effects of seasonality and treatment process on the community structures of ammonia-oxidizing archaea (AOA) and bacteria (AOB). And then DNA-based stable isotope probing (DNA-SIP) was applied to explore the active ammonia oxidizers. The results of high-throughput sequencing indicated that treatment processes varied AOB communities rather than AOA communities. AOA slightly outnumbered AOB in most of the samples, whose abundance was significantly correlated with temperature. DNA-SIP results showed that the majority of AOB amoA gene was labeled by 13C-substrate, while just a small amount of AOA amoA gene was labeled. As revealed by high-throughput sequencing of heavy DNA, Nitrosomonadaceae-like AOB, Nitrosomonas sp. NP1, Nitrosomonas oligotropha and Nitrosomonas marina were the active AOB, and Nitrososphaera viennensis dominated the active AOA. The results indicated that AOB, not AOA, dominated active ammonia oxidation in the test WWTP.

Shifts in bacterial community composition and abundance of nitrifiers during aerobic granulation in two nitrifying sequencing batch reactors.

Shifts in bacterial community composition and abundance of nitrifiers during aerobic granulation, and the effects of wastewater composition on them were investigated using Illumina sequencing and quantitative PCR. The bacterial diversity decreased sharply during the post-granulation period. Although cultivated with different wastewater types, aerobic granular sludge (AGS) formed with similar bacterial structure. The bacterial structure in AGS was completely different from that of seed sludge. The minor genera in seed sludge, e.g., Arcobacter, Aeromonas, Flavobacterium and Acinetobacter, became the dominant genera in AGS. These genera have the potential to secrete excess extracellular polymer substances. Whereas, the dominant genera in seed sludge were found in less amount or even disappeared in AGS. During aerobic granulation, ammonia-oxidizing archaea were gradually washed-out. While, ammonia-oxidizing bacteria, complete ammonia oxidizers and nitrite-oxidizing bacteria were retained. Overall, in this study, the bacterial genera with low relative abundance in seed sludge are important for aerobic granulation.

[Short-term Effect of Roxithromycin on Abundance and Diversity of Ammonia-Oxidizing Microorganisms in Activated Sludge].

In this study, the short-term effect of roxithromycin(ROX) on the abundance and diversity of ammonia-oxidizing archaea(AOA) and ammonia-oxidizing bacteria(AOB) based on amoA gene in activated sludge were investigated by high-throughput sequencing and quantitative real-time PCR(qPCR). High-throughput sequencing overcomes the drawbacks of low sequencing depth, significant randomness and great bias of traditional Sanger sequencing. This approach can provide enough sequencing depth to comprehensively investigate the sensitive and insensitive ammonia-oxidizing microorganisms under ROX selective pressure. Lab-scale reactors were operated under ten different ROX levels. The results indicated that the environmental(0.3-30 µg·L-1) and medium(300 µg·L-1and 3000 µg·L-1) levels of ROX did not affect ammonia oxidation, while the higher concentration(5000-12000 µg·L-1) of ROX showed a significant negative effect on ammonia oxidation. The environmental and medium levels of ROX stimulated the growth of AOA, however, the higher level of ROX decreased the abundance of AOA. In addition, different levels of ROX(except 0.3 µg·L-1) caused the decrease of the abundance of AOB, which suggested that AOA was less sensitive than AOB under ROX selective pressure. The results of high-throughput sequencing showed that ROX selective pressure caused the decrease of the numbers of OTUs for AOA and increase of that for AOB. The insensitive AOA, accounting for 57.70%-97.81% of the total sequences, were Candidatus Nitrososphaera gargensis and Candidatus Nitrosoarchaeum koreensis. The insensitive AOB were Nitrosomonas oligotropha, Nitrosospira multiformis, Nitrosomonas watsonii and Nitrosomonas halophilus, accounting for 0.76%-5.10% of the total sequences. These results also indicated that AOA was insensitive to ROX, but AOB was sensitive to ROX. RDA analyses showed that AOA Ca. Nitrososphaera gargensis, Ca. Nitrosoarchaeum koreensis and AOB N. oligotropha, N. watsonii, N. halophilus were positively correlated with ROX concentrations.

[Microbial Population Dynamics During Sludge Granulation in a Simultaneous Nitrogen and Phosphorus Removal System].

In this study, domestic sewage was utilized to cultivate aerobic granular sludge (AGS) in a simultaneous nitrogen and phosphorus removal (SNPR) system. The bacterial population dynamics during the aerobic sludge granulation were investigated to reveal the granulation mechanisms using Illumina MiSeq PE300 high-throughput sequencing. Quantitative real time polymerase chain reactions (PCR) were used to investigate shifts in the abundance of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), nitrite-oxidizing bacteria (NOB) and polyphosphate accumulating organisms (PAOs). After cultivation for 100 d, the AGS was compact and demonstrated good SNPR performance. During the AGS formation process, extracellular polysaccharides obviously increased, while extracellular proteins kept relatively stable. The abundance of AOA significantly decreased during the formation of AGS process, while the abundance of PAOs increased. The bacterial diversity increased at first and then decreased during the formation of AGS. The bacterial community changed dramatically during aerobic sludge granulation. Persistent operational taxonomic units (OTUs) accounted for 92.70% of the total sequences. Proteobacteria (31.07%-53.67%), Bacteroidetes (6.70%-16.50%) and Chloroflexi (7.84%-13.36%) were the dominant phyla. Candidatus competibacter was obviously enriched in the AGS formation process (increased from 0.11% in the seed sludge to 35.33% in the AGS) and may play an important role in the formation of AGS.

Diversity, abundance and activity of ammonia-oxidizing microorganisms in fine particulate matter.

Increasing ammonia emissions could exacerbate air pollution caused by fine particulate matter (PM2.5). Therefore, it is of great importance to investigate ammonia oxidation in PM2.5. This study investigated the diversity, abundance and activity of ammonia oxidizing archaea (AOA), ammonia oxidizing bacteria (AOB) and complete ammonia oxidizers (Comammox) in PM2.5 collected in Beijing-Tianjin-Hebei megalopolis, China. Nitrosopumilus subcluster 5.2 was the most dominant AOA. Nitrosospira multiformis and Nitrosomonas aestuarii were the most dominant AOB. Comammox were present in the atmosphere, as revealed by the occurrence of Candidatus Nitrospira inopinata in PM2.5. The average cell numbers of AOA, AOB and Ca. N. inopinata were 2.82 × 104, 4.65 × 103 and 1.15 × 103 cell m-3 air, respectively. The average maximum nitrification rate of PM2.5 was 0.14 µg (NH4+-N) [m3 air·h]-1. AOA might account for most of the ammonia oxidation, followed by Comammox, while AOB were responsible for a small part of ammonia oxidation. Statistical analyses showed that Nitrososphaera subcluster 4.1 was positively correlated with organic carbon concentration, and Nitrosomonas eutropha showed positive correlation with ammonia concentration. Overall, this study expanded our knowledge concerning AOA, AOB and Comammox in PM2.5 and pointed towards an important role of AOA and Comammox in ammonia oxidation in PM2.5.

[Abundance and Community Composition of Ammonia-Oxidizing Archaea in Two Completely Autotrophic Nitrogen Removal over Nitrite Systems].

Ammonia oxidation is the first and rate-limiting step of nitrification, which was thought to be only performed by ammonia-oxidizing bacteria (AOB). In recent years, ammonia-oxidizing archaea (AOA) was also confirmed to take part in ammonia oxidation. The diversity and abundance of AOA have been investigated in various environments, however, little is known regarding the AOA in the completely autotrophic nitrogen removal over nitrite (CANON) wastewater treatment process. In this study, the abundance and diversity of AOA were investigated in the biofilm and flocculent activated sludge collected in a lab-scale (L) CANON system and a pilot-scale (P) CANON systems, respectively. The quantitative real time PCR (qPCR) was applied to investigate the abundance of AOA and the diversity of AOA was determined by polymerase chain reaction (PCR), cloning and sequencing. The qPCR results showed that the average abundance of AOA amoA gene of L and P was 2.42 x 10(6) copies x g(-1) dry sludge and 6.51 x 10(6) copies x g(-1) dry sludge, respectively. The abundance of AOA in biofilm was 10.1-14.1 times higher than that in flocculent activated sludge. For P system, the abundance of AOA in flocculent activated sludge was 1.8 times higher than that in biofilm. The results indicated that the abundance of AOA might be affected by different sludge morphology. The diversity of AOA in P system was extremely limited, only one OTU was observed, which was classified into Nitrosopumilus subcluster 5.2. The diversity of AOA in L system was higher, eight OTUs were observed, which were classified into five genera: Nitrososphaera subcluster 9, subcluster 8.1, subcluster 4.1, subcluster 1.1 and Nitrosopumilus subcluster 5.2. The diversity and abundance of AOA were different in CANON systems with different sludge morphology. AOA may play an important role in ammonia oxidation in CANON system.