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1.
Bioresour Technol ; 289: 121714, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31323719

RESUMO

In this study, multistage contact oxidation reactor (MCOR) with a novel carrier was used for treatment of high-strength sodium saccharin wastewater (SSW) under stepwise increasing salinities from 1.0% to 8.0%. The results revealed that MCOR could effectively remove the organic pollutants from SSW when influent salinity was no more than 4.5%; the chemical oxygen demand (COD) and NH4+-N removal efficiency under the optimal operating parameters ranged up to 91.5% and 92.7%, respectively. Microbial diversity analysis illustrated that the dominant microbes in SSW treatment system were substantially distinct at different salinities. Pseudomonas was predominant at salinity of 3.5%, while Marinobacterium (a species involved in COD removal) was enriched to a greater degree at salinity of 7.0%. CCA suggested that salinity was the main factor for dynamic evolutions of microbial community structures. This work demonstrated that MCOR is an appropriate method for the treatment of high-strength, high-salinity SSW.


Assuntos
Microbiota , Sacarina/metabolismo , Águas Residuárias/química , Análise da Demanda Biológica de Oxigênio , Reatores Biológicos/microbiologia , Oxirredução , Sacarina/análise , Salinidade
2.
Bioresour Technol ; 289: 121711, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31323722

RESUMO

Transient anoxia due to the periodic anoxic/aerobic operation is beneficial for the nitrite-oxidizing bacteria (NOB) suppression. A continuous reactor of modified University of Cape Town process treating municipal wastewater was equipped with alternating anoxic/aerobic zones to maintain nitritation. Higher nitrite accumulation ratio in the oxic zones was achieved through transient anoxia and shorter aerobic actual hydraulic retention time (15 min), but it steeply deteriorated from above 95.0% to 21.0% after elevated temperature (25 °C). Batch experiments indicated that the existence of initial nitrite at the starting of aerobic phase promoted the recovery of NOB activity from transient anoxia and inhibited the activity of ammonium-oxidizing bacteria. Furthermore, a supplemental modeling further confirmed that the specific growth rates of NOB (µNOB) decreased at the anoxic phase and the recovery extent of µNOB after anoxic exposure have a positive correlation with the initial concentrations of nitrite, leading to the failure of maintaining nitritation.


Assuntos
Nitritos/metabolismo , Compostos de Amônio/metabolismo , Bactérias/crescimento & desenvolvimento , Reatores Biológicos/microbiologia , Águas Residuárias/microbiologia
3.
World J Microbiol Biotechnol ; 35(8): 116, 2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31332538

RESUMO

Exploration of renewable energy sources is an imperative task in order to replace fossil fuels and to diminish atmospheric pollution. Hydrogen is considered one of the most promising fuels for the future and implores further investigation to find eco-friendly ways toward viable production. Expansive processes like electrolysis and fossil fuels are currently being used to produce hydrogen. Biological hydrogen production (BHP) displays recyclable and economical traits, and is thus imperative for hydrogen economy. Three basic modes of BHP were investigated, including bio photolysis, photo fermentation and dark fermentation. Photosynthetic microorganisms could readily serve as powerhouses to successively produce this type of energy. Cyanobacteria, blue green algae (bio photolysis) and some purple non-sulfur bacteria (Photo fermentation) utilize solar energy and produce hydrogen during their metabolic processes. Ionic species, including hydrogen (H+) and electrons (e-) are combined into hydrogen gas (H2), with the use of special enzymes called hydrogenases in the case of bio photolysis, and nitrogenases catalyze the formation of hydrogen in the case of photo fermentation. Nevertheless, oxygen sensitivity of these enzymes is a drawback for bio photolysis and photo fermentation, whereas, the amount of hydrogen per unit substrate produced appears insufficient for dark fermentation. This review focuses on innovative advances in the bioprocess research, genetic engineering and bioprocess technologies such as microbial fuel cell technology, in developing bio hydrogen production.


Assuntos
Eletrólise , Hidrogênio/metabolismo , Fontes de Energia Bioelétrica , Reatores Biológicos/microbiologia , Cianobactérias/metabolismo , Fermentação , Hidrogenase/metabolismo , Oxigênio/metabolismo , Fotólise , Fotossíntese
4.
J Environ Sci (China) ; 84: 112-121, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31284902

RESUMO

Much remains unknown about compositional variations in soluble microbial products (SMP) with the shift of the substrate condition from a feast to a famine phase in biological treatment systems. This study demonstrated that the formation of SMP could be suppressed by up to 75% during the famine phase with the addition of essential nutrients. In contrast, presence of electron acceptor did not play any significant role during the stress condition, showing the similar amounts of SMP (r = 0.98, p < 0.05) formation between the bioreactors supplied with air and N2. The SMP formed in the famine phase was more bio-refractory in the famine versus the feast phase with a linear correlation shown between the production and their aromatic structures in the composition (R2 > 0.95). The fluorescence excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC) revealed the presence of four different fluorescent components, including two protein-like (C1 and C4), fulvic-like (C2), and humic-like (C3) components, in the SMP and bEPS formed at different conditions. Both C1 and C4 showed increasing trends (R2 > 0.95) with the length of starvation in the bioreactors without essential nutrients. Nutrient availability was found to be a key factor to quench the production of large-sized biopolymers. This study provides a wealth of information on operation conditions of activated sludge treatment systems to minimize large sized SMP molecules (particularly proteins), which typically exert many environmental concerns to effluent organic matter quality.


Assuntos
Reatores Biológicos/microbiologia , Esgotos/microbiologia , Gerenciamento de Resíduos
5.
J Environ Sci (China) ; 84: 133-143, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31284905

RESUMO

In this study, raw Arundo donax (A. donax) pieces were applied as carbon source and biofilm carriers for denitrification in a lab-scale moving bed biofilm reactor (MBBR) for the treatment of reverse osmosis concentrate gathered from local wastewater reuse plant. At stable phase (about 60 days), efficient denitrification performance was obtained with 73.2% ±â€¯19.5% NO3--N average removal and 8.10 ±â€¯3.45 g N/(m3·day) NO3--N average volumetric removal rate. Mass balance analysis showed that 4.84 g A. donax was required to remove 1 g TN. Quantitative real-time PCR analysis results showed that the copy numbers of 16S r-RNA, narG, nirS, nosZ and anammox gene of carrier biofilm and suspended activated sludge in the declination phase (BF2 and AS2) were lower than those of samples in the stable phase (BF1 and AS1), and relatively higher copy numbers of nirS and nirK genes with lower abundance of narG and nosZ genes were observed. High-throughput sequencing analysis was conducted for BF2 and AS2, and similar dominant phyla and classes with different abundance were obtained. The class Gammaproteobacteria affiliated with the phylum Proteobacteria was the most dominant microbial community in both BF2 (52.6%) and AS2 (41.7%). The PICRUSt prediction results indicated that 33 predictive specific genes were related to denitrification process, and the relative abundance of 18 predictive specific genes in BF2 were higher than those in AS2.


Assuntos
Reatores Biológicos/microbiologia , Desnitrificação , Consórcios Microbianos , Nitrogênio/isolamento & purificação , Poaceae/química , Poaceae/microbiologia , Purificação da Água
6.
J Environ Sci (China) ; 84: 144-154, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31284906

RESUMO

A systemic strategy was proposed to improve aerobic granular sludge (AGS) stability and nitrogen (N) removal efficiency by optimizing feeding mode and substrate aiming at complicated wastewater characteristics. Key functional groups at the genus level identified by high-throughput sequencing were evaluated as well. The results showed that anaerobic feeding mode and acetate promoted the compact AGS formation with excellent total nitrogen (TN) removal efficiency (averaging 91.7% ±â€¯4.1%) at various dissolved oxygen conditions. While the aerobic feeding mode led to a loose AGS structure with a vulnerable anaerobic core and poor TN removal efficiency (averaging 58.8% ±â€¯7.4%). Simultaneous nitrification and denitrification process played the dominant role in N removal in compact AGS over the alternating nitrification and denitrification process. High-concentration glucose undermined feast-famine condition with filamentous bacteria growth out of granule and decreased TN removal efficiency to 67.3% ±â€¯15.2%. Lower food to microorganism ratio may result in a lower N removal rate attributed to the sharply increased biomass concentration fed by glucose. Ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, denitrifying bacteria, and denitrifying phosphorus accumulation organisms enriched during AGS granulation also contributed to the efficient N removal. The proposed strategy provided insights into the relationship between various factors and stable AGS formation, and systemic operation methods for various complicated wastewater treatment.


Assuntos
Reatores Biológicos/microbiologia , Nitrogênio/isolamento & purificação , Acetatos , Biomassa , Glucose , Microbiota , Tamanho da Partícula , Esgotos
7.
Int J Syst Evol Microbiol ; 69(9): 2954-2957, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31282854

RESUMO

Comparative analyses of Diaphorobacter polyhydroxybutyrativorans SL-205T and Diaphorobacter nitroreducens NA10BT were conducted for clarifying their taxonomic relationship. The sequences of the 16S rRNA gene and nine housekeeping genes of SL-205T and NA10BT shared high similarities, above 98.8 %. Whole-genomic comparison between the two strains revealed a digital DNA-DNA hybridization estimate of 85.1 % and an average nucleotide identity of 98.3 % that were well above respective recognized thresholds for bacterial species delineation, strongly indicating that they represent the same genomospecies. The metabolic, physiological and chemotaxonomic features of SL-205T were also shown to be congruent with those of NA10BT. Therefore, we conclude that Diaphorobacter polyhydroxybutyrativoransQiu et al. 2015 is a later heterotypic synonym of Diaphorobacter nitroreducens Khan and Hiraishi 2003.


Assuntos
Comamonadaceae/classificação , Filogenia , Esgotos/microbiologia , Animais , Técnicas de Tipagem Bacteriana , Composição de Bases , Reatores Biológicos/microbiologia , DNA Bacteriano/genética , Ácidos Graxos/química , Genes Bacterianos , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Suínos
8.
Chemosphere ; 233: 843-851, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31340410

RESUMO

The bioremediation efficiency of petroleum hydrocarbons in natural soil-water systems is regulated by active microbial populations and other system parameters. Relevant factors include the transfer rate of petroleum contaminants from a medium into microorganisms, the partitioning behavior of contaminants from water into the soil organic matter (SOM), and the influence of the dissolved organic matter (DOM) on the contaminant level in water. The objectives of this study was aimed to determine the correlation among bioavailability of petroleum hydrocarbons, SOM content, and DOM level in soil-water systems. Heptadecane, pristane, and decylcyclohexane were selected as model hydrocarbon contaminants. The bioavailability of target contaminants in soil was examined using soils of different SOM contents (2% and 20%) in slurry bioreactors. In addition, the contaminant bioavailability as affected by various DOM levels (0-100 mgC/L) was also examined. The results showed that the SOM content affected the degrading rate of hydrocarbons significantly, where the rate constant was 4 times higher in 2% SOM microcosm than in the 20% SOM bioreactor for heptadecane degradation. Similarly, the pristane degrading efficiency after 240 h operation was 95% for the 2% SOM microcosm and only 38% for the 20% SOM microcosm. The hydrocarbon degradation rates in water phase were found to be enhanced by the added DOM level. A positive correlation existed between the contaminant bioavailability and the contaminant level in water as impacted by the SOM content in soil and the DOM level in water.


Assuntos
Alcanos/metabolismo , Cicloexanos/metabolismo , Gordonia (Bactéria)/metabolismo , Petróleo/metabolismo , Poluentes do Solo/análise , Terpenos/metabolismo , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Disponibilidade Biológica , Reatores Biológicos/microbiologia , Solo/química , Microbiologia do Solo , Água/química
9.
Environ Sci Process Impacts ; 21(7): 1193-1203, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31204424

RESUMO

Coupling of chemical oxidation using persulfate with bioremediation has been proposed as a method to increase remedial efficacy at petroleum hydrocarbon contaminated sites. To support this integrated treatment approach, an understanding of persulfate impact on the indigenous microbial community is necessary for system design. As sulfate-reducing bacteria (SRB) are active in most aquifer systems and can utilize the sulfate generated from the degradation of persulfate, this study assessed the impact on SRB and the supporting anaerobic microbial community when exposed to persulfate in a continuous flow system. A series of bioreactors (1000 L) packed with anaerobic aquifer material were operated for an 8 month acclimatization period before being continuously subjected to benzene, toluene, ethylbenzene and xylenes (total BTEX 3 mg L-1). After 2 months, the bioreactors were then exposed to an unactivated persulfate solution (20 g L-1), or an alkaline-activated persulfate solution (20 g L-1, pH 12) then effluent-sampled for 60 days following. A combination of culture and molecular-based techniques were used to monitor SRB presence and structural profiles in the anaerobic SRB-specific and broader microbial community. Post-exposure, the rate of BTEX mass removal remained below pre-exposure values; however, trends suggest that full recovery would be expected. Rebound of SRB-specific and the associated microbial community to pre-exposure levels were observed in all exposed bioreactors. Structural community profiles identified recovery in both microbial species and diversity indices. Findings from this investigation demonstrate robustness of SRB in the presence of a supporting microbial community and, thus, are suitable organisms for target use during bioremediation in an integrated system with persulfate.


Assuntos
Derivados de Benzeno/análise , Reatores Biológicos/microbiologia , Desulfovibrio/crescimento & desenvolvimento , Água Subterrânea/química , Microbiota , Sulfatos/química , Poluentes Químicos da Água/análise , Anaerobiose , Biodegradação Ambiental , Oxirredução
10.
Chemosphere ; 233: 472-481, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31181494

RESUMO

Ammonia-rich lagoon supernatant was treated using anammox process in an integrated fixed-film activated sludge (IFAS) laboratory reactor. Effective anammox activities were demonstrated over 259 days of operation. The ammonium removal efficiency reached 94% in Phase I with influent concentrations of NH4+, NO2- and chemical oxygen demand (COD) at 250 mg-N/L, 325 mg-N/L, and 145 mg-COD/L, and reached 88% in Phase II at 420 mg-N/L, 525 mg-N/L, and 305 mg-COD/L. When supplemented with nitritation effluent for nitrite sources in Phase III, the influent COD concentration increased to 583 mg-COD/L without loss of ammonia removal efficiency (87%). The specific anammox activity was higher in biofilm than in the suspended flocs (P < 0.05), increased from Phase I to II (P < 0.05), and decreased in Phase III. Ammonia removal related genes were quantified using qPCR. Results showed higher anammox gene (AMX nirS) prevalence in biofilm, while denitrification genes (nosZ and narG) were higher in flocs (P < 0.05). Microbial community analysis showed that the seeded anammox bacteria Candidatus Brocadia was maintained at 19% in the biofilm and only 0.3% in the flocs. The major taxa in the flocs were related to denitrifiers. The floc community was affected largely under high COD conditions, but the biofilm community was not. These results suggest that the anammox activity in biofilm is resilient to high COD loadings, due to the existence of flocs with denitrification activity. The segregation of bacterial communities between biofilm and flocs in the anammox IFAS system resulted in high ammonia removal efficiency and resistance to high organic loadings.


Assuntos
Amônia/análise , Biofilmes/crescimento & desenvolvimento , Reatores Biológicos/microbiologia , Esgotos/microbiologia , Purificação da Água/métodos , Análise da Demanda Biológica de Oxigênio , Desnitrificação/genética , Genes Bacterianos , Modelos Teóricos , Planctomycetales/genética
11.
World J Microbiol Biotechnol ; 35(7): 98, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31222401

RESUMO

Sterols are crucial functional components for eukaryotic cell membrane. Due to versatile activities, sterols show wide applications in food and pharmaceutical industries. Ergosterol not only reflects cell growth but also serves as the precursor for manufacturing steroid drugs. To date, the ergosterol biosynthetic pathway in yeast has been reported, and the industrial production of ergosterol is achieved by yeast fermentation or extraction from fungal mycelia. Here, we summarize its biosynthesis, regulation, transportation, and subcellular location of enzymes in yeast. In particular, we review the regulation of ergosterol biosynthesis at transcriptional, translational and post-translational levels. Furthermore, we advocate metabolic engineering and fermentation strategies for high-level production of ergosterol. This study may provide evaluable insights into metabolic engineering of yeast for scaled-up fermentation production of ergosterol or beyond.


Assuntos
Ergosterol/biossíntese , Leveduras/metabolismo , Reatores Biológicos/microbiologia , Candida albicans/metabolismo , Cryptococcus neoformans/metabolismo , Fermentação , Engenharia Metabólica , Saccharomyces cerevisiae/metabolismo , Schizosaccharomyces/metabolismo
12.
World J Microbiol Biotechnol ; 35(7): 101, 2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31236717

RESUMO

Propionibacterium acidipropionici produces propionic acid from different sugars and glycerol; the production can be improved by high cell density fermentations using immobilized cells that help to overcome the limitations of the non-productive lag phase and product inhibition. In this study, the use of stress factors to induce P. acidipropionici to form biofilm and its use as an immobilization procedure in fermentations in bioreactors for producing propionic acid was investigated. Citric acid and sodium chloride increased exopolysaccharide production, biofilm forming capacity index and trehalose production. Analysis of the expression of trehalose synthesis-related genes otsA and treY by RT-qPCR showed significantly increased expression of only treY during log phase with citric acid, while FISH analysis showed expression of treY and luxS under the influence of both stress factors. The stress factors were then used for development of microbial biofilms as immobilization procedure on Poraver® and AnoxKaldnes® carriers in recycle batch reactors for propionic acid production from 20 g/L glycerol. Highest productivities of 0.7 and 0.78 g/L/h were obtained in Poraver® reactors, and 0.39 and 0.43 g/L/h in AnoxKaldnes® reactors with citric acid and NaCl, respectively.


Assuntos
Biofilmes , Propionatos/metabolismo , Propionibacterium/metabolismo , Estresse Fisiológico , Reatores Biológicos/microbiologia , Células Imobilizadas , Fermentação , Regulação da Expressão Gênica , Genes Bacterianos , Glicerol/metabolismo , Hibridização in Situ Fluorescente , Microscopia de Força Atômica , Propionibacterium/genética , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/isolamento & purificação , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Trealose/metabolismo
13.
Int J Food Microbiol ; 304: 106-118, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31176963

RESUMO

Nicaraguan cocoa bean fermentations of several single local cocoa varieties originating from the same region (North Highlands of Nicaragua, San Jose de Bocay/El Cuá) were compared to fermentations of blended cocoa varietals from other producing regions of the country (Waslala and Nueva Guinea) making use of High Throughput Sequencing techniques, metabolite target analysis and sensory evaluation of cocoa liquor samples. A succession of the important cocoa-related yeasts Hanseniaspora uvarum/opuntiae, Saccharomyces cerevisiae and/or Pichia kudriavzevii was seen for single varietals and Nueva Guinea fermentations, while Kazachstania humilis dominated the mid and end phase of the Waslala cocoa fermentations. Tatumella species (mainly Tatumella terrea and Tatumella punctata) predominated the bacterial community at the onset of all fermentations followed by unusually late (generally 2 days into the fermentations) appearance of Lactobacillus fermentum relative to fermentations in other parts of the World. Acetobacter spp. were the main acetic acid bacteria during all fermentations, but also Gluconobacter spp. were involved in some single-variety fermentations. All fermentations proved complete as determined by metabolite analysis with bean sucrose being fully depleted and pulp sugars exhausted after 48-72 h of fermentation. From an organoleptic point of view, all Nicaraguan cocoas of this study reflected fine fruity (citrus or berry-like) flavours with distinct herbal or caramel notes. Floral notes were associated with the cases where P. kudriavzevii was involved in the later stages of fermentation. Intense citrus/fruity character was related to high pulp and bean citrate concentrations. Off-notes were found in some over-fermented batches where Bacillus spp. was detected. No relation between cut-test results and organoleptic appreciation was seen.


Assuntos
Bactérias/metabolismo , Cacau/microbiologia , Chocolate/microbiologia , Fermentação/fisiologia , Fungos/metabolismo , Ácido Acético/metabolismo , Acetobacter/metabolismo , Bactérias/isolamento & purificação , Reatores Biológicos/microbiologia , Enterobacteriaceae/metabolismo , Fungos/isolamento & purificação , Gluconobacter/metabolismo , Hanseniaspora/metabolismo , Lactobacillus fermentum/metabolismo , Pichia/metabolismo , Saccharomyces cerevisiae/metabolismo
14.
Chemosphere ; 232: 430-438, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31158638

RESUMO

Long-term effects of Pb2+ on the operating performance and membrane fouling of two hydrolytic-anoxic-oxic-membrane bioreactors treating synthetic electroplating wastewater were investigated. The COD, NH4+-N and TN removal efficiencies decreased by 5.5%, 10.4% and 7.9% with long-term exposure of 2 mg L-1 Pb2+, while serious decreases achieved 25.4%, 35.0% and 26.2% with 6 mg L-1 Pb2+ exposure, respectively. 2 mg L-1 Pb2+ mitigated the cake layer fouling rate by 25.4% but increased the pore blocking rate by 69.1%, which was contributed by the increase of low and moderate molecular weight (MW) components in the soluble and colloidal foulants (SCFs). 6 mg L-1 Pb2+ accelerated the cake layer fouling rate by 101.1%, but mitigated the pore blocking rate by 6.4% due to the increase of high MW SCFs (especially polysaccharides). Thermodynamic analyses showed that Pb2+ regulated the concentration and protein/polysaccharide ratio of loosely bound extracellular polymeric substances, thus changing the flocs hydrophobicity and aggregation capacity, leading the cake layer fouling rate variation.


Assuntos
Incrustação Biológica , Reatores Biológicos/microbiologia , Galvanoplastia , Chumbo/toxicidade , Membranas Artificiais , Águas Residuárias/química , Poluentes Químicos da Água/toxicidade , Aerobiose , Anaerobiose , Chumbo/análise , Poluentes Químicos da Água/análise
15.
Chemosphere ; 232: 327-336, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31154194

RESUMO

Guar is extensively used during shale gas exploitation and is a major component in the flowback water. The viscosity of guar has adverse effects for the treatment of flowback water. This study investigated the degradation of guar at different salinities with an up-flow anaerobic sludge blanket (UASB) reactor. The effects of salinity on guar degradation, granular characteristics and microbial community were also studied. Results showed that more than 79% of guar was removed at hydraulic retention time (HRT) of 10 h, even at a concentration of 10000 mg L-1 of NaCl. Increasing salinity decreased granular size and hydrophobicity, but improved the secretion of EPS (especially for protein). Low salt condition 2500 mg L-1 presented faster degradation rate of guar. Salinity resulted in insignificant difference on bacterial community, but decreased the abundance of methanogens. Bacteroides, Prolixibacter and Pelolinea are essential genera in guar degradation. The results demonstrated the potential of UASB in the treatment of flowback water.


Assuntos
Reatores Biológicos/microbiologia , Eliminação de Resíduos Líquidos/métodos , Anaerobiose , Bactérias , Cyamopsis , Microbiota , Salinidade , Esgotos/microbiologia , Água
16.
Bioelectrochemistry ; 129: 154-161, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31174109

RESUMO

A bioelectrochemical system (BES) is a technology with potential for accelerating the degradation of recalcitrant compounds, the components and configurations of which are important for treatment performance. In the present work, a membraneless sleeve-type BES (termed BioE) was designed for the treatment of synthetic coal gasification wastewater (CGW, phenol as a model pollutant) and real CGW. Compared with the biological control (termed Bio), the phenol removal rate and COD removal efficiency increased by 2.6 and 2.1 fold in the BioE, respectively. However, the coulombic efficiency of this system was relatively low, ranging from 0.42% to 2.6%. This combination of results indicated that anode respiration was not the main process in the BioE. The increased CH4 production and higher levels of methanogens obtained from the BioE confirmed that the methanogenic process proceeded, possibly facilitated by the diffusion of H2 from the cathode to the anode. This study provides new insight into biocathode function for COD oxidation removal in BESs. Moreover, this study indicates that pursuing a high coulombic efficiency may not be necessary for wastewater treatment, as it consumes less energy at the lower value.


Assuntos
Reatores Biológicos/microbiologia , Carvão Mineral/análise , Fenóis/isolamento & purificação , Eliminação de Resíduos Líquidos/instrumentação , Águas Residuárias/análise , Poluentes Químicos da Água/isolamento & purificação , Análise da Demanda Biológica de Oxigênio , Eletrodos , Desenho de Equipamento
17.
Syst Appl Microbiol ; 42(4): 481-487, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31153679

RESUMO

Biogas plants achieve its highest yield on plant biomass only with the most efficient hydrolysis of cellulose. This is driven by highly specialized hydrolytic microorganisms, which we have analyzed by investigating enrichment strategies for the isolation of cellulolytic bacteria out of a lab-scale biogas fermenter. We compared three different cultivation media as well as two different inoculation materials: Enrichment on filter paper in nylon bags (in sacco) or raw digestate. Next generation sequencing of the V3/V4 region of the bacterial 16S rRNA of metagenomic DNA from six different enrichment cultures, each in biological triplicates, revealed an average richness of 48 different OTU's with an average evenness of 0.3 in each sample. ß-Diversity of the bacterial community revealed significant differences between the two sampling techniques or the different media used. The isolation attempt of single cellulolytic organisms resulted in several clonal pure cultures. Regardless which medium or inoculation material, well-known cellulolytic key players such as Clostridium cellulosi, Herbinix hemicellulosilytica and Hungateiclostridium thermocellum were among the isolates. The inoculation material as well as the cultivation conditions are crucial to cultivate the representative cellulolytic organisms. Taking raw digestate as inoculation material and using the same material, filtered and sterilized, for supplementing media allowed to imitate the natural habitat. Pre-enrichment of cellulolytic organisms directly in their natural habitat led to significant advantages concerning high diversity and high abundance of unknown cellulolytic organisms, which is a key factor for the isolation of hitherto unknown species.


Assuntos
Biocombustíveis/microbiologia , Celulose/metabolismo , Microbiologia Industrial/métodos , Microbiota , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Biodiversidade , Biomassa , Reatores Biológicos/microbiologia , Meios de Cultura , DNA Bacteriano/genética , Metagenoma , Microbiota/genética , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
18.
Int J Syst Evol Microbiol ; 69(8): 2471-2476, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31180314

RESUMO

A nitrite-tolerant denitrifying bacterium, strain GL14T, was isolated from the nitrification/denitrification bioreactor in our laboratory. Strain GL14T was Gram-stain-negative, rod-shaped, non-spore-forming, facultatively anaerobic and motile by means of a single polar flagellum. Phylogenetic analyses based on 16S rRNA gene sequences indicated that it was assigned to the genus Pseudomonas with highest 16S rRNA gene sequence similarity (98.77 %) to Pseudomonas xanthomarina DSM 18231T and Pseudomonassongnenensis NEAU-ST5-5T, followed by Pseudomonasstutzeri ATCC 17588T (98.42 %), Pseudomonaskunmingensis HL22-2T (98.29 %) and Pseudomonaszhaodongensis NEAU-ST5-21T (98.22 %). Phylogenetic analysis based on both concatenated sequences of the 16S rRNA gene and two housekeeping genes (gyrB and rpoD) and genome sequences further clarified the intrageneric phylogenetic position of strain GL14T. The DNA G+C content of GL14T was 63.1 mol%. The results of digital DNA-DNA hybridization (highest 24.2 % of DNA-DNA relatedness) based on the Genome-to-Genome Distance Calculator and average nucleotide identity analyses (highest 80.23 %) confirmed that the strain was distinctly delineated from known species of the genus Pseudomonas. The major fatty acids were summed feature 8 (C18 : 1ω7c/C18 : 1ω6c), C16 : 0, summed feature 3 (C16 : 1ω7c/C16 : 1ω6c), C17 : 0cyclo and C12 : 0. The respiratory quinone was ubiquinone Q-9. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. Based on the phylogenetic, genomic, phenotypic and chemotaxonomic analyses, it was concluded that strain GL14T represents a novel species of the genus Pseudomonas, for which the name Pseudomonas nitrititolerans sp. nov. is proposed. The type strain is GL14T (=CGMCC 1.13874T=NBRC 113853T).


Assuntos
Reatores Biológicos/microbiologia , Nitritos/metabolismo , Filogenia , Pseudomonas/classificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Desnitrificação , Ácidos Graxos/química , Genes Bacterianos , Nitrificação , Hibridização de Ácido Nucleico , Fosfolipídeos/química , Pseudomonas/isolamento & purificação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Ubiquinona/química
19.
Sci Total Environ ; 684: 67-77, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31150877

RESUMO

Occurrence and effects of antibiotics and antibiotic resistance in various wastewater treatment systems have been widely investigated. However, few reports address the impacts of antibiotic exposure on wastewater treatment system operating characteristics, especially the characteristics of sludge granules under long-term operation. In this study, two laboratory scale anoxic-aerobic systems were established to investigate the combined effects of tetracycline and sulfamethoxazole. The results indicated that under long-term exposure to 5 mg·L-1 tetracycline and 1 mg·L-1 sulfamethoxazole, removals of chemical oxygen demand and total nitrogen were inhibited, the tendency of sludge bulking was increased, more filamentous bacteria were observed and more extracellular polymeric substance was secreted. This tendency was stronger than that from exposure to tetracycline alone. Molecular biological analysis indicated that the microbial community changed significantly especially with Thiothrix (instead of Sphaerotilus under tetracycline alone) becoming the dominant population under combined antibiotics. The results are relevant for operation of WTS receiving wastewater with high antibiotic concentrations.


Assuntos
Antibacterianos/farmacologia , Reatores Biológicos/microbiologia , Microbiota/efeitos dos fármacos , Esgotos/análise , Eliminação de Resíduos Líquidos , Aerobiose , Anaerobiose , Sulfametoxazol/farmacologia , Tetraciclina/farmacologia
20.
Chemosphere ; 233: 67-75, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31170585

RESUMO

Ozone (O3) treatment is an effective strategy in maintaining high efficiency and control of biomass accumulation in gas phase biofiltration. However, little is known about the long-term impact of O3 on the microbial communities. In the present study, two biofilters treating gaseous ethyl acetate were operated continuously for 230 days with inlet loads up to 180 g m-3∙h-1. A biofilter operated under continuous O3 addition (90 ppbv) yielded consistently higher removal efficiency (RE) and elimination capacity (EC) compared to the control system. After 120 days of operation, a lower biomass content accompanied by a pH of 1.5 was observed in the ozonated biofilter, which was 2 units lower compared to the control reactor. Both reactors developed a distinct microbial community composition over the course of 230 days. The bacterial community was dominated in both biofilters by Beijerinckia and Gluconacetobacter, while Rhinocladiella similis, Trichosporon veenhuissi and Exophilia oligosperma were abundant in the fungal community. These findings suggest that ozonation of the biofiltration systems not only reduced clogging, but also contributed to the selection of biomass suitable for degradation of ethyl acetate.


Assuntos
Acetatos/química , Poluentes Atmosféricos/química , Ozônio/química , Eliminação de Resíduos Líquidos/métodos , Acetatos/análise , Poluentes Atmosféricos/análise , Bactérias/metabolismo , Biomassa , Reatores Biológicos/microbiologia , Filtração , Microbiota
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