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1.
J Environ Manage ; 317: 115474, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35751273

RESUMO

Nitrogen loss during composting is closely related to NH4+-N conversion, and ammonia-oxidizing bacteria (AOB) are important microorganisms that promote NH4+-N conversion. Since the biological activity of conventional AOB agents used for compost inoculation declines rapidly during the thermophilic phase of composting, new compound inoculants should be developed that are active during that phase. In the current study, the effects of inoculating cattle manure compost with newly isolated AOB (5%, v/w) [thermotolerant AOB X-2 strain (T-AOB-2), mesophilic AOB X-4 strain (M-AOB-4), and AOB X-2 combined with AOB X-4 (MT-AOB-2-4)] on the conversion of nitrogen, compost maturity, and the resident microbial community were studied. During 35 days of composting, compared with the control, AOB inoculation reduced NH3 emissions by 29.98-46.94%, accelerated the conversion of NH4+-N to NO2--N, increased seed germination values by 13.00-25.90%, and increased the abundance of the microbial community at the thermophilic phase (16.38-68.81%). Network analysis revealed that Bacillaceae play a crucial role in the composting process, with the correlation coefficients: 0.83 (p < 0.05) with NH3, 0.64 (p < 0.05) with NH4+-N, and 0.81 (p < 0.05) with NO2--N. In addition, inoculation with MT-AOB-2-4 notably increased the total nitrogen content of compost, prolonged the sanitation stage, and promoted compost maturity. Hence, MT-AOB-2-4 may be used to increase the microbial community abundance and improve the efficiency of cattle manure composting.


Assuntos
Betaproteobacteria , Compostagem , Microbiota , Amônia , Animais , Bactérias , Bovinos , Esterco/microbiologia , Nitrogênio , Dióxido de Nitrogênio , Oxirredução , Solo
2.
Chemosphere ; 305: 135411, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35738404

RESUMO

A main challenge in rapid nitrogen removal from rejected water in wastewater treatment plants (WWTPs) is growth of biomass by nitrite-oxidizing bacteria (NOB) and ammonia-oxidizing bacteria (AOB). In this study, partial nitritation (PN) coupled with air-lift granular unit (AGU) technology was applied to enhance nitrogen-removal efficiency in WWTPs. For successful PN process at high-nitrogen-influent conditions, a pH of 7.5-8 for high free-ammonia concentrations and AOB for growth of total bacterial populations are required. The PN process in a sequential batch reactor (SBR) with AGU was modeled as an activated sludge model (ASM), and dynamic calibration using full-scale plant data was performed to enhance aeration in the reactor and improve the nitrite-to-ammonia ratio in the PN effluent. In steady-state and dynamic calibrations, the measured and modeled values of the output were in close agreement. Sensitivity analysis revealed that the kinetic and stoichiometric parameters are associated with growth and decay of heterotrophs, AOB, and NOB microorganisms. Overall, 80% of the calibrated data fit the measured data. Stage 1 of the dynamic calibration showed NO2 and NO3 values close to 240 mg/L and 100 mg/L, respectively. Stage 2 showed NH4 values of 200 mg/L at day 30 with the calibrated effluent NO2 and NO3 value of 250 mg/L. In stage 3, effluent NH4 concentration was 200 mg/L at day 60.


Assuntos
Betaproteobacteria , Purificação da Água , Amônia , Bactérias , Reatores Biológicos/microbiologia , Calibragem , Desnitrificação , Nitritos , Nitrogênio , Dióxido de Nitrogênio , Oxirredução , Esgotos/microbiologia , Águas Residuárias/microbiologia
3.
Sci Rep ; 12(1): 7299, 2022 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-35508560

RESUMO

Nitrification, a key pathway of nitrogen (N) loss from agricultural soils, is performed by ammonia-oxidizing bacteria (AOB) and archaea (AOA). We examined the seasonal dynamics (2 years) of ammonia oxidizer gene abundances across a gradient of soil carbon (C) and N in a semi-arid soil after 8 years of tillage and crop residue treatments. AOB was more dominant than AOA in the surface soil, as AOA were undetected in 96% of samples. Seasonal variation in AOB abundance was related to substrate availability; AOB gene copy numbers increased at the end of the growing season (during summer fallow) following higher concentrations in dissolved organic matter soil water. This suggests increased co-location between AOB and substrate resources in pores still filled with water as the soils dried. AOB was however not statistically related to soil ammonium concentrations, soil water content, rainfall or temperature. Organic matter inputs enhanced AOB abundance independent of seasonal variation. AOB abundance was greatest in autumn and immediately preceding the start of the growing season, and coincided with elevated soil nitrate concentrations. The growth of the AOB population is likely to contribute to increased risk of N loss through leaching and/or denitrification at the start of the crop growing season following summer fallow.


Assuntos
Archaea , Betaproteobacteria , Amônia/metabolismo , Archaea/genética , Archaea/metabolismo , Bactérias/genética , Bactérias/metabolismo , Betaproteobacteria/metabolismo , Nitrificação , Nitrogênio/metabolismo , Oxirredução , Filogenia , Estações do Ano , Solo/química , Microbiologia do Solo , Água/metabolismo
4.
Int J Biol Macromol ; 210: 44-52, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35537581

RESUMO

Biochemical and biophysical studies revealed that chitinase O from Chitiniphilus shinanonensis (CsChiO) exhibits considerable thermotolerance, possibly due to the formation of a stable structural conformation. CsChiO is an exochitinase with a temperature optimum of 70 °C. The secondary structures of CsChiO and its catalytic domain (Cat-CsChiO) are only marginally affected upon heating up to 90 °C, as revealed by circular dichroism (CD) spectroscopy. Differential scanning calorimetric (DSC) studies revealed that CsChiO exhibits two endothermic transitions at ca. 51 °C (Tm1) and 59 °C (Tm2), whereas Cat-CsChiO shows a single endothermic transition at 52 °C. Together, the CD and DSC analyses suggested that the catalytic domain of CsChiO undergoes a thermotropic transition at ~52 °C from native state to another stable structural conformation. Results from molecular dynamic simulations corroborated that Cat-CsChiO adopts a stable structural conformation above 50 °C by partial unfolding. Thermotolerant CsChiO would be useful for the conversion of chitin, which is highly abundant, to biologically active COS. This study unveiled the adaptability of enzymes/proteins in nature to perform biological functions at elevated temperatures.


Assuntos
Betaproteobacteria , Quitinases , Termotolerância , Betaproteobacteria/metabolismo , Varredura Diferencial de Calorimetria , Quitina/química , Quitinases/metabolismo , Dicroísmo Circular , Termodinâmica
5.
Sci Total Environ ; 838(Pt 1): 155923, 2022 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-35577082

RESUMO

Ammonia-oxidizing bacteria (AOB) play an important role in the global nitrogen cycle and have broad applications in the nitrogen removal from wastewater. However, the AOB species are sensitive to environmental factors and usually form tight relationships with other microbes, making the AOB isolation and maintenance are difficult and time-consuming. In this study, the relationship that occurred between AOB and their bacterial partners was found to be able to improve the ammonia oxidation; during the co-cultivation, the magnesium ions (Mg2+) with removal rate as high as 36.7% was removed from culture medium by the concomitant bacterial species, which was regarded as the main reason for improving ammonia oxidation. During the pure cultivation of AOB isolate, when the concentration of Mg2+ reduced to low levels, the ammonia-oxidizing activity was more than 5 times and the amoA gene expression was more than 12 times higher than that grown in the initial culture medium. Based on a newly designed culture medium, the ammonia oxidation of AOB isolate grown in liquid culture was significantly promoted and the visible AOB colonies with much more number and larger diameter were observed to form on agar plates. With the addition of high concentration of calcium carbonate (CaCO3), AOB colonies could be easily and specifically identified by following the hydrolytic zones that formed around AOB colonies. Another AOB isolates were successively obtained from different samples and within a short time, suggesting the feasibility and effectivity of this culture medium and strategy on the AOB isolation from environments.


Assuntos
Amônia , Betaproteobacteria , Amônia/metabolismo , Archaea , Bactérias/metabolismo , Betaproteobacteria/metabolismo , Íons/metabolismo , Magnésio , Oxirredução , Filogenia
6.
Sci Total Environ ; 835: 155568, 2022 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-35490817

RESUMO

Human activities severely affect the global nitrogen (N) cycle. Croplands receive intensive N fertilization; consequently, cropland and natural ecosystem differentiation often results in community and functional variation in N-transforming microbes, including nitrifiers, which perform nitrification central to N cycle. However, evidence of such variation is mostly limited to ammonia oxidizers (AO) in local fields, excluding soil heterogeneity and nitrite-oxidizing bacteria (NOB); the variation under diverse climatic and soil conditions is not comprehensively understood. We conducted a large-scale survey of 131 cropland and natural sites in China. The community patterns of ammonia-oxidizing bacteria (AOB) and NOB differed significantly between croplands and some natural ecosystems, whereas ammonia-oxidizing archaea (AOA) were not affected by ecosystem type. The AOB population and nitrification potential (NP) were significantly higher in agroecosystems than in natural systems except wetlands. Fewer co-occurrence interactions involving nitrifiers were observed in croplands than in natural ecosystems except forests, systematically indicating the ecological diversification of nitrifiers in potential microbial associations among these habitats. Ecosystem type, pH, organic matter (OM), total phosphorus (TP), mean annual temperature (MAT) and mean annual precipitation (MAP) were primary drivers of nitrifier community and functional shifts. This study provides the first large-scale evidence of overall nitrifier community (i.e., AOA, AOB and NOB) and potential functional shifts between agroecosystems and natural environments, enabling predictions of terrestrial N cycle under foreseeable natural land use conversions and global climate change.


Assuntos
Betaproteobacteria , Ecossistema , Amônia , Archaea , Bactérias , Humanos , Nitrificação , Nitritos , Oxirredução , Filogenia , Solo , Microbiologia do Solo
7.
Sci Total Environ ; 831: 154972, 2022 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-35367558

RESUMO

The responses of the operational performance and bacterial community structure of a nitrification membrane bioreactor (MBR) to elevated ammonia loading rate (ALR) were investigated. Effective nitrification performance was achieved at high ALR up to 3.43 kg NH4+-N/m3·d, corresponding to influent NH4+-N concentration of 2000 mg/L. Further increasing influent NH4+-N concentration to 3000 mg/L, the MBR system finally became completely inefficient due to the combined inhibition effect of salinity, free ammonia and free nitrous acid on nitrification. Ammonia-oxidizing bacteria (AOB) Nitrosomonas were enriched with the increase of ALR. The relative abundance of Nitrosomonas in the sludge with ALR of 2.57 kg NH4+-N/m3·d was up to 14.82%, which were 9-fold and 53-fold higher than that in seed sludge and the sludge with ALR of 0.10 kg NH4+-N/m3·d, respectively. The phylogenetic analysis of AOB amoA genes showed that Nitrosomonas europaea/mobilis lineage are chiefly responsible for catalyzing ammonia oxidation at high ALRs.


Assuntos
Betaproteobacteria , Nitrificação , Amônia/química , Bactérias/genética , Reatores Biológicos/microbiologia , Nitrosomonas , Ácido Nitroso , Oxirredução , Filogenia , Salinidade , Esgotos/química
8.
Sci Total Environ ; 833: 155132, 2022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-35405242

RESUMO

Bioaugmentation of nitrifying cultures can accelerate nitrification during startup and transition periods of recirculating aquaculture system (RAS) operations. To formulate nitrifying cultures for RASs, impacts of ammonia and salinity (NaCl) on culturing nitrifying microorganisms were comprehensively investigated by including currently known groups of nitrifying microorganisms (ammonia oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), comammox, Nitrospira, and Nitrobacter). By varying ammonia loading rate (ALRs of 1.6, 8, 20, 40, 60 and 150 mgN/L/d) of continuous-flow bioreactors fed with inorganic medium experimented for culture preparation, cultures containing distinct patterns of nitrifying communities were produced. Operating the reactors at the ALRs of ≤40 mgN/L/d, resulting in the effluent total ammonia nitrogen (TAN) and nitrite concentrations of ≤2.64 and ≤0.53 mgN/L, respectively, delivered the consortia consisting of a broad spectrum of substrate affinity nitrifying microorganisms. At the lower ranges of these ALRs (≤8 mgN/L/d), the most desirable consortia comprising comparable numbers of AOB, AOA, and comammox could be produced (the effluent TAN concentrations of ≤0.20 mgN/L), which would be resilient for applying in various RAS types. Enriching the cultures at the ALRs of ≥60 mgN/L/d allowed only the nitrifying microorganisms with low substrate affinity to dominate, incongruent with the consortia found in actual RASs. AOB were adaptable at all salinity studied (2, 15, and 30 g/L), while AOA and comammox were sensitive to elevated salinity (15 and 30 g/L, respectively). The ammonia removal rate of a culture prepared at 2 g/L salinity decreased largely when applied at 15 and 30 g/L. In contrast, those prepared at 15 and 30 g/L were more robust to different salinity. Separately preparing the cultures at different salinity for uses in freshwater-low salinity and brackish-marine RASs is recommended. The findings of this work enhance our understanding on how to formulate nitrifying culture augmentation for used in different RAS types.


Assuntos
Amônia , Betaproteobacteria , Archaea , Nitrificação , Oxirredução , Filogenia , Cloreto de Sódio , Triacetonamina-N-Oxil
9.
Chemosphere ; 301: 134653, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35447203

RESUMO

Biodegradation is regarding as the most important organic micro-pollutants (OMPs) removal mechanism during riverbank filtration (RBF), but the OMPs co-metabolism mechanism and the role of NH4+-N during this process are not well understood. Here, we selected atenolol as a typical OMP to explore the effect of NH4+-N concentration on atenolol removal and the role of ammonia oxidizing bacteria (AOB) in atenolol biodegradation. The results showed that RBF is an effective barrier for atenolol mainly by biodegradation and adsorption. The ratio of biodegradation and adsorption to atenolol removal was dependent on atenolol concentration. Specifically, atenolol with low concentration (500 ng/L) is almost completely removed by adsorption, while atenolol with higher concentration (100 µg/L) is removed by biodegradation (51.7%) and adsorption (30.8%). Long-term difference in influent NH4+-N concentrations did not show significant impact on atenolol (500 ng/L) removal, which was mainly dominated by adsorption. Besides, AOB enhanced the removal of atenolol (100 µg/L) as biodegradation played a more crucial role in removing atenolol under this concentration. Both AOB and heterotrophic bacteria can degrade atenolol during RBF, but the degree of AOB's contribution may be related to the concentration of atenolol exposure. The main reactions occurred during atenolol biodegradation possibly includes primary amide hydrolysis, hydroxylation and secondary amine depropylation. About 90% of the bio-transformed atenolol was produced as atenolol acid. AOB could transform atenolol to atenolol acid by inducing primary amide hydrolysis but failed to degrade atenolol acid further under the conditions of this paper. This study provides novel insights regarding the roles played by AOB in OMPs biotransformation during RBF.


Assuntos
Atenolol , Betaproteobacteria , Amidas , Amônia/metabolismo , Betaproteobacteria/metabolismo , Biodegradação Ambiental , Filtração , Oxirredução
10.
Huan Jing Ke Xue ; 43(4): 2204-2208, 2022 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-35393844

RESUMO

Soil pH is recognized as an important environmental factor in determining the niche differentiation for ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) communities. Species of comammox, a single microorganism capable of the complete oxidation of ammonia to nitrate, have recently been discovered. Metagenomic analysis and quantitative PCR showed that Comammox Nitrospira were found in a wide range of environments, including soil. Comammox bacteria are differentiated into one of two clades (A and B) based on the phylogeny of genes encoding the α-subunit of ammonia monooxygenase genes (amoA). However, all discovered Comammox Nitrospira strains have been isolated and cultured in aquatic ecosystems, including N. inopinata, N. nitrosa, and N. nitrificans, all belonging to clade A. Currently, Comammox Nitrospira has not been obtained from soil environments, which limits our understanding of soil Comammox Nitrospira. Here we hypothesized that, as AOA and AOB, the ecological site of Comammox Nitrospira may also be affected by pH. Therefore, soil samples with differing pH were collected, and the abundances and community structures were studied to elucidate the mechanism of pH effect on the distributions and community compositions of Comammox Nitrospira in soil. Quantitative PCR of comammox clade A and clade B amoA genes in DNA extracts were performed using QuantStudio TM6 Flex Real-Time PCR Systems. The community compositions for Comammox Nitrospira were studied by the cloning libraries of amoA genes method. The results showed that the abundance of Comammox clade A amoA gene in acidic paddy soil was two orders of magnitude higher than that in neutral paddy soil (P<0.05), and the abundance of Comammox clade B in acidic paddy soil was significantly higher than that in neutral paddy soil (P<0.05); the abundance of Comammox clade A amoA gene in acidic paddy soil was 60 times higher than that of clade B, whereas the abundance ratio of Comammox clade A and clade B amoA genes in neutral paddy soil was about two times higher. These results indicated that soil pH significantly affected the abundance of Comammox Nitrospira. The results of cloning and sequencing showed that the Comammox in neutral paddy soil was mainly N. inopinata, which belonged to clade A; no strain belonging to clade B was annotated. Comammox clade A in acidic paddy soil was mainly Composed of N. inopinata and N. nitrosa, and clade B was mainly uncultured bacterium (FN395328). The results indicated that soil pH was an important factor in shaping Comammox Nitrospira community structure. Comammox Nitrospira were detected in all soil samples, and Comammox clade A had a preference for acidic environments. It seemed that species from N. nitrosa possessed the ecological niche of low pH environments, whereas species from N. inopinata preferred to live in neutral environments. In conclusion, pH had a significant effect on the abundance and community structure of Comammox Nitrospira, which was one of the important factors affecting the niche differentiation of Comammox Nitrospira.


Assuntos
Betaproteobacteria , Solo , Amônia , Archaea/genética , Bactérias , Ecossistema , Concentração de Íons de Hidrogênio , Nitrificação , Oxirredução , Filogenia , Solo/química , Microbiologia do Solo
11.
Water Res ; 216: 118301, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35364353

RESUMO

Recent research has shown enhanced biological phosphorus removal (EBPR) from municipal wastewater at warmer temperatures around 30 °C to be achievable in both laboratory-scale reactors and full-scale treatment plants. In the context of a changing climate, the feasibility of EBPR at even higher temperatures is of interest. We operated two lab-scale EBPR sequencing batch reactors for > 300 days at 30 °C and 35 °C, respectively, and followed the dynamics of the communities of polyphosphate accumulating organisms (PAOs) and competing glycogen accumulating organisms (GAOs) using a combination of 16S rRNA gene metabarcoding, quantitative PCR and fluorescence in situ hybridization analyses. Stable and nearly complete phosphorus (P) removal was achieved at 30 °C; similarly, long term P removal was stable at 35 °C with effluent PO43-_P concentrations < 0.5 mg/L on half of all monitored days. Diverse and abundant Candidatus Accumulibacter amplicon sequence variants were closely related to those found in temperate environments, suggesting that EBPR at this temperature does not require a highly specialized PAO community. A slow-feeding strategy effectively limited the carbon uptake rates of GAOs, allowing PAOs to outcompete GAOs at both temperatures. Candidatus Competibacter was the main GAO, along with cluster III Defluviicoccus members. These organisms withstood the slow-feeding regime, suggesting that their bioenergetic characteristics of carbon uptake differ from those of their tetrad-forming relatives. Comparative cycle studies revealed higher carbon and P cycling activity of Ca. Accumulibacter when the temperature was increased from 30 °C to 35 °C, implying that the lowered P removal performance at 35 °C was not a direct effect of temperature, but a result of higher metabolic rates of carbon (and/or P) utilization of PAOs and GAOs, the resultant carbon deficiency, and escalated community competition. An increase in the TOC-to-PO43--P ratio (from 25:1 to 40:1) effectively eased the carbon deficiency and benefited PAOs. In general, a slow-feeding strategy and sufficiently high carbon input benefited a high and stable EBPR at 35 °C, representing basic conditions suitable for full-scale treatment plants experiencing higher water temperatures.


Assuntos
Betaproteobacteria , Fósforo , Betaproteobacteria/metabolismo , Reatores Biológicos , Carbono , Estudos de Viabilidade , Aquecimento Global , Glicogênio/metabolismo , Hibridização in Situ Fluorescente , Fósforo/metabolismo , Polifosfatos/metabolismo , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo
12.
Water Res ; 217: 118338, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35397371

RESUMO

Enhanced biological phosphorus removal (EBPR) performance and microbial community dynamics during dry and wet-weather conditions of a full-scale treatment plant was evaluated by converting a section of activated sludge basins using low-cost operational modifications into an anoxic/anaerobic zone to promote EBPR. Two trains of the activated sludge system at the Des Moines, Iowa Metropolitan Wastewater Reclamation Facility were used for the study with one train modified for EBPR, and the other remained as nitrification-only for comparison. In addition to measuring the modification effectiveness for phosphorus removal, performance was compared during dry and wet weather conditions over the course of two summer seasons to improve understanding of wet and dry weather dynamics for EBPR. DNA sequencing and qPCR tests were conducted to develop an understanding of microbial population changes between control and modified basins and wet and dry weather conditions. Basin hydraulic retention times varied from 2.6 to 12.7 hours with an average of 8.9 hours. EBPR activity was successfully established in the modified basins with average phosphorus content of the return activated sludge 0.032 ± 0.002 compared to 0.016 ± 0.001 mg TP/mg TSS (95% confidence) in the control basins. Phosphorus removal was significantly decreased by prolonged wet weather conditions, particularly in year two of the study, however the modified basin maximum removal of 96% and average of 43.7 ± 5.3% remained significantly higher than the maximum of 46% and average 12.6 ± 2.4% removal in the control basins. DNA sequencing showed a significant increase in relative abundance of phyla Chloroflexi, Nitrospirae, and Verrucomicrobia in the modified basins, but no correlation to EBPR performance. qPCR indicated significant increase in relative quantity of Accumulibacter, but not for Actinetobacter-like phosphorus accumulating organisms (PAOs), which includes the PAO Tetrasphaera. Significant abundance of some Accumulibacter clades found within the modified basins was contrary to previous literature which focused on small-scale and batch studies. A higher than expected dominance of clade I and increased relative quantities of clades IIB and IIC during extended wet weather was observed which may have contributed to rapid recovery of phosphorus removal when dry weather resumed. The abundance of PAOs did not significantly correlate with changes in phosphorous removal performance, contrary to reports from previous small-scale and batch studies.


Assuntos
Betaproteobacteria , Microbiota , Reatores Biológicos , Fósforo , Esgotos , Tempo (Meteorologia)
13.
Curr Microbiol ; 79(6): 158, 2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35416552

RESUMO

A Gram-reaction-negative, facultatively aerobic, motile, non-spore-forming, rod-shaped, and denitrifying bacterium, designated dN18-1T, was isolated from activated sludge, Republic of Korea. This bacterium was investigated via a polyphasic approach to reveal its taxonomic position. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain dN18-1T belongs to the genus Paludibacterium and is most closely related to P. purpuratum KCTC 42852T (96.2% sequence similarity), P. yongneupense KACC 11601T (96.1%), and P. paludis BCRC 80514T (95.2%). The average nucleotide identity values and digital DNA-DNA hybridization values calculated between strain dN18-1T and the closely related strains were 72.5-73.1% and 19.0-19.6%. The genome comprises of 3,347,996 bp with a G + C content of 57.3 mol%. Strain dN18-1T possesses ubiquinone Q-8 as a predominant respiratory quinone, and summed feature 3 (C16:1 ω6c and/or C16:1 ω7c), summed feature 8 (C18:1 ω6c/C18:1 ω7c), C16:0 and C12:0, as its major fatty acids (>5%). The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and four unidentified aminophospholipids. The results of ANI calculation, digital DNA-DNA hybridization, physiological and biochemical tests allowed phenotypic differentiation of strain dN18-1T from rephrase other genus Paludibacterium species with validly published names. Therefore, this isolate represents a novel species, for which the name Paludibacterium denitrificans sp. nov. (type strain dN18-1T = KACC 19537T = CGMCC 1.16961T) is proposed.


Assuntos
Betaproteobacteria , Esgotos , Bactérias/genética , Técnicas de Tipagem Bacteriana , Betaproteobacteria/genética , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Fosfolipídeos/química , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Esgotos/microbiologia
14.
Water Res ; 217: 118434, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35427829

RESUMO

Antibiotic resistance genes (ARGs) have become an important public health concern. Particularly, although several ARGs have been identified in wastewater treatment plants (WWTPs), very few studies have characterized their impacts on reactor performance. Therefore, our study sought to investigate the effect of a representative conjugative transfer plasmid (RP4) encoding multidrug resistance genes on ammonia oxidation. To achieve this, we established sequencing batch reactors (SBRs) and a conjugation model with E. coli donor strains carrying the RP4 plasmid and a typical ammonia-oxidating (AOB) bacterial strain (Nitrosomonas europaea ATCC 25978) as a recipient to investigate the effect of conjugative transfer of plasmid RP4 on AOB. Our findings demonstrated that the RP4 plasmid carried by the donor strains could be transferred to AOB in the SBR and to Nitrosomonas europaea ATCC 25978. In SBR treated with donor strains carrying the RP4 plasmid, ammonia removal efficiency continuously decreased to 71%. Once the RP4 plasmid entered N. europaea ATCC 25978 in the conjugation model, ammonia removal was significantly inhibited and nitrite generation was decreased. Furthermore, the expression of several functional genes related to ammonia oxidation in AOB was suppressed following the transfer of the RP4 plasmid, including amoA, amoC, hao, nirK, and norB. In contrast, the cytL gene encoding cytochrome P460 was upregulated. These results demonstrated the ecological risk of ARGs in WWTPs, and therefore measures must be taken to avoid their transfer.


Assuntos
Amônia , Betaproteobacteria , Amônia/metabolismo , Antibacterianos/farmacologia , Bactérias/metabolismo , Betaproteobacteria/metabolismo , Desnitrificação , Resistência a Múltiplos Medicamentos , Escherichia coli/genética , Nitrogênio , Oxirredução , Plasmídeos/genética
15.
Sci Total Environ ; 826: 154178, 2022 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-35240169

RESUMO

Real-time nitrite control in water is necessary for environmental safety and human health, and has triggered the research and development of novel detection methods. Previous studies have made great progress on enzyme-free and enzyme electrochemical sensors. However, enzyme-free sensors have low selectivity and a complex preparation process, and enzyme sensors have short lifetimes, and these issues need to be addressed. In this work, we proposed for the first time a highly specific and sensitive biofilm sensor based on nitrite-oxidizing bacteria (NOB) for the bio-electrochemical detection of nitrite in water. The mechanism of nitrite detection was attributed to the competition of oxygen between aerobic respiration of the NOB and the cathode oxygen reduction on the carbon felt electrode, resulting in a decrease in current. This decrease in current (ΔI) had a linear relationship with the nitrite concentration in the range of 0.1 to 1 mg L-1 and 1 to 10 mg L-1, which was corresponding to the sensitivities of 48.62 and 2.24 µA mM-1 cm-2, respectively. And the limit of detection (LOD) was calculated to be 0.033 mg L-1 (2.39 µM) with a signal-to-noise ratio of 3. Moreover, several common interfering ions had no effect on the nitrite detection owing to the functional microbial species (NOB) and weakly electrochemical behavior of electrode at the low potential of -0.1 V, showing high specificity for nitrite detection of biofilm sensor. Therefore, the actual nitrified wastewater was well detected by the biofilm sensor. In addition, allylthiourea (ATU) took good effect on the resistance of the influence of ammonia oxidizing bacteria (AOB) in the biofilm sensor, maintaining the high selectivity of biofilm sensor in case the biofilm sensor was fouled with AOB. The biofilm sensor in our work showed good selectivity, sensitivity and stability in long-term detection.


Assuntos
Betaproteobacteria , Nitritos , Amônia , Bactérias , Reatores Biológicos/microbiologia , Humanos , Oxirredução , Oxigênio , Água
16.
Water Res ; 216: 118291, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35313179

RESUMO

Microalgal-bacterial consortium (MBC) process has been proposed as an alternative to conventional activated sludge process for nitrogen removal from wastewater. As one of the most influencing parameters, light irradiation effects on microalgae have been extensively investigated. However, light influence on the performance of nitrifiers in activated sludge and its mechanism remains unclear. In this study, the effects of three factors (light irradiation power, irradiation time and sludge concentration) on activities and physiological characteristics of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were systematically studied through both the Design of Experiments driven response surface methodology (RSM) approach and light-nitrification kinetic modeling. Results indicated that light irradiation with the specific light energy density (Es) at 0.0203-0.1571 kJ·mg-1 VSS (80-160 W/400-1000 µmol·m-2·s-1, 2.0-5.0 h and 2750-4250 mg·L-1) stimulated the relative AOB activities (rAOB) by 120.0%. This was supported by the increased electron transport system activity, key enzyme activity (AMO) , gene expression (amoA) and energy generation (ATP consumption) in the light treatment. Moreover, further Es increasing up to 0.18 kJ·mg-1 VSS inhibited both AOB and NOB activities. The inhibition was ascribed to the joint light responses of metabolic disorders and lipid peroxidation. The findings enhance our understanding of nitrifiers' physiological responses to short-term light irradiation, and promote the development of MBC as a sustainable approach for wastewater treatment.


Assuntos
Betaproteobacteria , Águas Residuárias , Amônia/metabolismo , Bactérias/metabolismo , Betaproteobacteria/metabolismo , Reatores Biológicos/microbiologia , Nitrificação , Nitritos/metabolismo , Oxirredução , Esgotos/microbiologia , Águas Residuárias/microbiologia
17.
Water Res ; 216: 118258, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35320769

RESUMO

This work analyzed, for the first time, the bioenergetics of PAOs and GAOs in full-scale wastewater treatment plants (WWTPs) for the uptake of different carbon sources. Fifteen samples were collected from five full-scale WWTPs. Predominance of different PAOs, i.e., Ca. Accumulibacter (0.00-0.49%), Tetrasphaera (0.37-3.94%), Microlunatus phosphovorus (0.01-0.18%), etc., and GAOs, i.e., Ca. Competibacter (0.08-5.39%), Defluviicoccus (0.05-5.34%), Micropruina (0.17-1.87%), etc., were shown by 16S rRNA gene amplicon sequencing. Despite the distinct PAO/GAO community compositions in different samples, proton motive force (PMF) was found as the key driving force (up to 90.1%) for the uptake of volatile fatty acids (VFAs, acetate and propionate) and amino acids (glutamate and aspartate) by both GAOs and PAOs at the community level, contrasting the previous understanding that Defluviicoccus have a low demand of PMF for acetate uptake. For the uptake of acetate or propionate, PAOs rarely activated F1, F0- ATPase (< 11.7%) or fumarate reductase (< 5.3%) for PMF generation; whereas, intensive involvements of these two pathways (up to 49.2% and 61.0%, respectively) were observed for GAOs, highlighting a major and community-level difference in their VFA uptake biogenetics in full-scale systems. However, different from VFAs, the uptake of glutamate and aspartate by both PAOs and GAOs commonly involved fumarate reductase and F1, F0-ATPase activities. Apart from these major and community-level differences, high level fine-scale micro-diversity in carbon uptake bioenergetics was observed within PAO and GAO lineages, probably resulting from their versatilities in employing different pathways for reducing power generation. Ca. Accumulibacter and Halomonas seemed to show higher dependency on the reverse operation of F1, F0-ATPase than other PAOs, likely due to the low involvement of glyoxylate shunt pathway. Unlike Tetrasphaera, but similar to Ca. Accumulibacter, Microlunatus phosphovorus took up glutamate and aspartate via the proton/glutamate-aspartate symporter driven by PMF. This feature was testified using a pure culture of Microlunatus phosphovorus stain NM-1. The major difference between PAOs and GAOs highlights the potential to selectively suppress GAOs for community regulation in EBPR systems. The finer-scale carbon uptake bioenergetics of PAOs or GAOs from different lineages benefits in understanding their interactions in community assembly in complex environment.


Assuntos
Actinomycetales , Betaproteobacteria , Acetatos , Actinomycetales/metabolismo , Adenosina Trifosfatases/metabolismo , Ácido Aspártico , Betaproteobacteria/metabolismo , Reatores Biológicos , Carbono/metabolismo , Metabolismo Energético , Ácido Glutâmico/metabolismo , Glicogênio/metabolismo , Fósforo/metabolismo , Polifosfatos/metabolismo , Propionatos , Propionibacteriaceae , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Succinato Desidrogenase/metabolismo
18.
Water Sci Technol ; 85(4): 1107-1119, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35228357

RESUMO

This study explored the microbial population dynamics of Accumulibacter (Acc) at low temperature and metabolic shift to limiting polyphosphate (Poly-P) in enhanced biological phosphorus removal (EBPR) system. The Accumulibacter-enriched EBPR systems, fed with acetate (HAc) and propionate (HPr) at 10 ± 1 °C respectively, were operated for 60 days in two identical SBR reactors (SBR-1 and SBR-2). The phosphorus removal performance in two systems was stable at 10 ± 1 °C, while the microbial community structure changed. Compared with the population structure in seed sludge, Accumulibacter clades reduced in the HAc system, while Acc I increased significantly in the HPr system. Low temperature was beneficial to the formation of granular sludge in the EBPR system, and the sludge granulation in the HAc system was more homogeneous than that in the HPr system. Accumulibacter in the HPr system can get ATP through glycogen accumulating metabolism (GAM) under limiting Poly-P condition at 10 ± 1 °C, while that in the HAc system cannot. This work suggests that poly-P levels can affect the metabolic pathway of Accumulibacter in EBPR systems under low temperature.


Assuntos
Betaproteobacteria , Polifosfatos , Betaproteobacteria/metabolismo , Reatores Biológicos , Fósforo/metabolismo , Polifosfatos/metabolismo , Esgotos , Temperatura
19.
Environ Microbiol ; 24(4): 2136-2156, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35315560

RESUMO

Complete genomes can be recovered from metagenomes by assembling and binning DNA sequences into metagenome assembled genomes (MAGs). Yet, the presence of microdiversity can hamper the assembly and binning processes, possibly yielding chimeric, highly fragmented and incomplete genomes. Here, the metagenomes of four samples of aerobic granular sludge bioreactors containing Candidatus (Ca.) Accumulibacter, a phosphate-accumulating organism of interest for wastewater treatment, were sequenced with both PacBio and Illumina. Different strategies of genome assembly and binning were investigated, including published protocols and a binning procedure adapted to the binning of long contigs (MuLoBiSC). Multiple criteria were considered to select the best strategy for Ca. Accumulibacter, whose multiple strains in every sample represent a challenging microdiversity. In this case, the best strategy relies on long-read only assembly and a custom binning procedure including MuLoBiSC in metaWRAP. Several high-quality Ca. Accumulibacter MAGs, including a novel species, were obtained independently from different samples. Comparative genomic analysis showed that MAGs retrieved in different samples harbour genomic rearrangements in addition to accumulation of point mutations. The microdiversity of Ca. Accumulibacter, likely driven by mobile genetic elements, causes major difficulties in recovering MAGs, but it is also a hallmark of the panmictic lifestyle of these bacteria.


Assuntos
Betaproteobacteria , Microbiota , Bactérias/genética , Betaproteobacteria/genética , Metagenoma , Metagenômica/métodos , Microbiota/genética , Esgotos/microbiologia
20.
Appl Environ Microbiol ; 88(7): e0234621, 2022 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-35285718

RESUMO

Aerobic methanotrophic activity is highly dependent on copper availability, and methanotrophs have developed multiple strategies to collect copper. Specifically, when copper is limiting (ambient concentrations less than 1 µM), some methanotrophs produce and secret a small modified peptide (less than 1,300 Da) termed methanobactin (MB) that binds copper with high affinity. As MB is secreted into the environment, other microbes that require copper for their metabolism may be inhibited as MB may make copper unavailable; e.g., inhibition of denitrifiers as complete conversion nitrate to dinitrogen involves multiple enzymes, some of which are copper-dependent. Of key concern is inhibition of the copper-dependent nitrous oxide reductase (NosZ), the only known enzyme capable of converting nitrous oxide (N2O) to dinitrogen. Herein, we show that different forms of MB differentially affect copper uptake and N2O reduction by Pseudomonas stutzeri strain DCP-Ps1 (that expresses clade I NosZ) and Dechloromonas aromatica strain RCB (that expresses clade II NosZ). Specifically, in the presence of MB from Methylocystis sp. strain SB2 (SB2-MB), copper uptake and nosZ expression were more significantly reduced than in the presence of MB from Methylosinus trichosporium OB3b (OB3b-MB). Further, N2O accumulation increased more significantly for both P. stutzeri strain DCP-Ps1 and D. aromatica strain RCB in the presence of SB2-MB versus OB3b-MB. These data illustrate that copper competition between methanotrophs and denitrifying bacteria can be significant and that the extent of such competition is dependent on the form of MB that methanotrophs produce. IMPORTANCE Herein, it was demonstrated that the different forms of methanobactin differentially enhance N2O emissions from Pseudomonas stutzeri strain DCP-Ps1 (harboring clade I nitrous oxide reductase) and Dechloromonas aromatica strain RCB (harboring clade II nitrous oxide reductase). This work contributes to our understanding of how aerobic methanotrophs compete with denitrifiers for the copper uptake and also suggests how MBs prevent copper collection by denitrifiers, thus downregulating expression of nitrous oxide reductase. This study provides critical information for enhanced understanding of microbe-microbe interactions that are important for the development of better predictive models of net greenhouse gas emissions (i.e., methane and nitrous oxide) that are significantly controlled by microbial activity.


Assuntos
Methylocystaceae , Methylosinus trichosporium , Pseudomonas stutzeri , Betaproteobacteria , Cobre/metabolismo , Imidazóis , Methylocystaceae/metabolismo , Óxido Nitroso/metabolismo , Oligopeptídeos , Pseudomonas stutzeri/metabolismo
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