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1.
Environ Int ; 132: 105107, 2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31476641

RESUMO

Integrating denitrifying anaerobic methane oxidation (DAMO) with Anammox provides alternative solutions to simultaneously remove nitrogen and mitigate methane emission from wastewater treatment. However, the practical application of DAMO has been greatly limited by slow-growing DAMO microorganisms living on low-solubility gaseous methane. In this work, DAMO and Anammox co-cultures were fast enriched using high concentration of mixed sludges from various environments, and achieved nitrogen removal rate of 76.7 mg NH4+-N L-1 d-1 and 87.9 mg NO3--N L-1 d-1 on Day 178. Subsequently, nitrogen removal rate significantly decreased but recovered quickly through increasing methane flushing frequency, indicating methane availability could be the limiting factor of DAMO activity. Thus, this work developed a novel Membrane Aerated Membrane Bioreactor (MAMBR), which equipped with gas permeable membrane for efficient methane delivery and ultrafiltration membrane for complete biomass retention. After inoculated with enriched sludge, nitrogen removal rates of MAMBR were significantly enhanced to 126.9 mg NH4+-N L-1 d-1 and 158.8 mg NO3--N L-1 d-1 by membrane aeration in batch test. Finally, the MAMBR was continuously fed with synthetic wastewater containing ammonium and nitrite to mimic the effluent from partial nitritation. When steady state with nitrogen loading rate of 2500 mg N L-1 d-1 was reached, the MAMBR achieved total nitrogen removal of 2496.7 mg N L-1 d-1, with negligible nitrate in effluent (~6.5 mg NO3--N L-1). 16S rRNA amplicon sequencing and fluorescence in situ hybridization revealed the microbial community dynamics during enrichment and application. The high performance of nitrogen removal (2.5 kg N m-3 d-1) within 200 days operation and excellent biomass retention capacity (8.67 kg VSS m-3) makes the MAMBR promising for practical application of DAMO and Anammox in wastewater treatment.

2.
Plant Dis ; : PDIS12182264RE, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31509495

RESUMO

Stripe rust, also known as yellow rust, is a significant threat to wheat yield worldwide. Adult plant resistance (APR) is the preferred way to obtain durable protection. Chinese winter wheat cultivar Xinong1376 has maintained acceptable APR to stripe rust in field environments. To characterize APR in this cultivar, 190 F10 recombinant inbred lines (RILs) developed from Xiaoyan81× Xinong1376 were evaluated for infection type and disease severity in fields either artificially or naturally inoculated. The population along with parents were genotyped using the Illumina 90K single-nucleotide polymorphism arrays. Six quantitative trait loci (QTL) were detected using the inclusive composite interval mapping method. QYr.nwafu-4AL and QYr.nwafu-6BL.3 conferred stable resistance in all environments, and likely corresponded to a gene-rich region on the long arm of chromosomes 4A and 6B. QYr.nwafu-5AL, QYr.nwafu-5BL, QYr.nwafu-3BL.1, and QYr.nwafu-3BL.2 were detected only in some environments but enhanced the level of resistance conferred by QYr.nwafu-4AL and QYr.nwafu-6BL.3. Kompetitive allele-specific PCR (KASP) markers developed for QYr.nwafu-4AL and QYr.nwafu-6BL.3 were confirmed in a subset of RILs and 133 wheat genotypes. The QTL on 4AL and 6BL with their linked KASP markers would be useful for marker-assisted selection to improve stripe rust resistance in breeding programs.

3.
Water Res ; 164: 114934, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31394464

RESUMO

Recent investigations verified that calcium peroxide (CaO2) could be used to pretreat waste activated sludge to promote methane yield from anaerobic digestion. However, the underlying mechanism of how CaO2 pretreatment promotes methane production is unclear. This work therefore aims to provide insights into such systems. Experimental results showed that with an increase of CaO2 dosage from 0 to 0.14 g/g VSS (volatile suspended solids) the methane yield increased linearly from 146.3 to 215.9 mL/g VSS. Further increases of CaO2 resulted in decreases in methane yield. CaO2 pretreatment promoted the disintegration of sludge and the degradation of sludge recalcitrant organics (especially humus and lignocellulose), thereby providing more substrates for subsequent methane production. Ultraviolet absorption spectroscopy indicated that CaO2 enhanced the cleavage of unsaturated conjugated bonds and reduced the aromaticity of humus and lignocellulose. Fourier transform infrared spectroscopy showed that CaO2 changed the structures and functional groups of humus and lignocellulose, making them transform to be biodegradable. GC/MS analyses exhibited that the degradation products of humus and lignocellulose included several types of small molecular organics such as ester-like, acid-like, and alcohol-like substances. Further investigation demonstrated that substantial methane could be produced from these degradation products. It was also found that the presence of recalcitrant organics was detrimental to anaerobes relevant to anaerobic digestion, and the degradation of such recalcitrant organics mitigated their inhibitions to the anaerobes. Model-based analysis suggested that CaO2 pretreatment increased the maximum methane yield and methane production rate, which were consistent with the analysis above.

4.
Environ Pollut ; 254(Pt A): 112951, 2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31374488

RESUMO

Microplastics can enter freshwater lakes through many sources. They can act as carriers to adsorb bacteria, virus, or pollutants (e.g., heavy metal and toxic organic compounds) that threaten human health through food chain. Microplastics can exist in surface water and sediments in freshwater lakes after they enter the lakes through discharge points. Wastewater discharge is the main cause of lake eutrophication and is the main emission source of microplastics. The correlation between lake trophic state and microplastic abundance has been rarely reported. This study investigated the microplastic contamination in surface water and sediments of 18 lakes along the middle and lower reaches of the Yangtze River Basin in the period of August-September 2018. The correlation between lake trophic state and microplastic abundance in surface water and sediments was investigated and discussed. The microplastic abundance in surface water was approximately two orders of magnitude lower than that in sediments in all 18 lakes. Hong Lake had the highest microplastic abundance in surface water sample, and Nantaizi Lake had the highest microplastic abundance in sediment sample. The dominant microplastic shape was fiber of 93.81% in surface water sample and 94.77% in sediment sample. Blue-colored microplastics were dominant in nearly all lakes in surface water sample (around 40%-60%) and sediment sample (around 60%-80%), followed by purple- and green-colored ones. The microplastics size <1 mm was dominant in surface water sample (around 40%-60%) and sediment sample (around 50%-80%). The dominant material was polypropylene in surface water sample (around 60%-80%) and sediment sample (around 40%-60%).

5.
Artigo em Inglês | MEDLINE | ID: mdl-31407454

RESUMO

Due to the high oxidation potential between AuI and AuIII , gold redox catalysis requires at least stoichiometric amounts of a strong oxidant. We herein report the first example of an electrochemical approach in promoting gold-catalyzed oxidative coupling of terminal alkynes. Oxidation of AuI to AuIII was successfully achieved through anode oxidation, which enabled facile access to either symmetrical or unsymmetrical conjugated diynes through homo-coupling or cross-coupling. This report extends the reaction scope of this transformation to substrates that are not compatible with strong chemical oxidants and potentiates the versatility of gold redox chemistry through the utilization of electrochemical oxidative conditions.

6.
Water Res ; 165: 114974, 2019 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-31450220

RESUMO

Although the enhancement of anammox performance for wastewater treatment due to the addition of small amount of acetate has been reported, discrepant metabolic responses of different anammox species have not been experimentally evaluated. Based on metagenomics and metatranscriptomic data, we investigated the competitiveness between two typical anammox species, Candidatus Jettenia caeni (J. caeni) and Candidatus Brocadia sinica (B. sinica), in anammox consortia under mixotrophic condition, where complex metabolic interactions among anammox bacteria and heterotrophs also changed with acetate addition. Contrary to J. caeni, the dissimilatory nitrate reduction to ammonium pathway of B. sinica was markedly stimulated for improving nitrogen removal. More acetate metabolic pathways and up-regulated AMP-acs expression for acetyl-CoA synthesis in B. sinica contributed to its superiority in acetate utilization. Interestingly, cross-feedings, including the nitrogen cycle, amino acid cross-feeding and B-vitamin metabolic exchange between B. sinica and other heterotrophs seemed to be enhanced with acetate addition, contributing to a reduction in metabolic energy cost to the whole community. Our work not only clarified the mechanism underlying discrepant responses of different anammox species to acetate, but also suggests a possible strategy for obtaining higher nitrogen removal rates in wastewater treatment under low C/N ratio.

7.
Water Sci Technol ; 80(1): 109-116, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31461427

RESUMO

Due to the high Brunauer-Emmett-Teller (BET) surface area of zeolitic imidazolate framework (ZIF)-8, a secondary crystallization method was used to prepare a particle electrode of γ-Al2O3@ZIF-8. According to the results from a field emission scanning electron microscope (SEM) and X-ray diffractometer (XRD), the particle electrode of γ-Al2O3 was successfully loaded with ZIF-8, and the BET surface area (1,433 m2/g) of ZIF-8 was over ten times that of γ-Al2O3. The key operation parameters of cell voltage, pH, initial RhB concentration and electrolyte concentration were all optimized. The observed rate constant (kobs) of the pseudo-first-order kinetic model for the electrocatalytic oxidation (ECO) system with the particle electrode of γ-Al2O3@ZIF-8 (15.2 × 10-2 min-1) was over five times higher than that of the system with the traditional particle electrode of γ-Al2O3 (2.6 × 10-2 min-1). The loading of ZIF-8 on the surface of γ-Al2O3 played an important role in improving electrocatalytic activity for the degradation of Rhodamine B (RhB), and the RhB removal efficiency of the three-dimensional (3D) electrocatalytic system with the particle electrode of γ-Al2O3@ZIF-8 was 93.5% in 15 min, compared with 27.5% in 15 min for the particle electrode of γ-Al2O3. The RhB removal efficiency was kept over 85% after five cycles of reuse for the 3D electrocatalytic system with the particle electrode of γ-Al2O3@ZIF-8.


Assuntos
Eletrodos , Rodaminas/química , Zeolitas , Oxirredução , Rodaminas/análise , Eliminação de Resíduos Líquidos
8.
Artigo em Inglês | MEDLINE | ID: mdl-31364965

RESUMO

Two novel strains, designated YLB-02T and YLB-04T, were isolated from the deep-sea sediments of Yap Trench located in the Pacific Ocean. Cells of the strains were Gram-stain-positive, oxidase- and catalase-positive and rod-shaped. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strain YLB-02T belonged to the genus Oceanobacillus and strain YLB-04T belonged to the genus Bacillus. Strain YLB-02T showed similarities of 96.9 % with Ornithinibacillus contaminans CCUG 53201T, 96.3 % with Oceanobacillus profundus CL-MP28T, 96.1 % with Oceanobacillus halophilus J8BT and 95.7 % with Oceanobacillus bengalensis Ma-21T. Strain YLB-04T showed the highest sequence similarity of 97.4 % with Bacillus notoginsengisoli SYP-B691T. The average nucleotide identity (ANI) and the DNA-DNA hybridisation (DDH) estimate values for strain YLB-02T and YLB-04T with their related type strains were below the respective threshold for species differentiation. The G+C contents of strains YLB-02T and YLB-04T were 37.3 and 45.4 mol%. The predominant (>10 %) cellular fatty acids of strain YLB-02T were iso-C14 : 0, iso-C15 : 0, iso-C16 : 0 and C16 : 1ω7c alcohol, and those of strain YLB-04T were C16 : 0, iso-C15 : 0, anteiso-C15 : 0 and C18 : 0. Their predominant ubiquinone was MK-7. The cell-wall peptidoglycan of strain YLB-02T contained glutamic acid, alanine, aspartic acid, lysine and ornithine, but no meso-diaminopimelic acid, while strain YLB-04T contained meso-diaminopimelic acid, glutamic acid, alanine, aspartic acid, lysine and ornithine. In addition to diphosphatidylglycerol (DPG) and phosphatidylglycerol (PG), the polar lipids of strain YLB-02T also consisted of an unidentified glycolipid (GL), two unidentified polar lipids (L1 and L2) and two unidentified phospholipids (PL1 and PL2), and those of strain YLB-04T also consisted of phosphatidylethanolamine (PE) and an unidentified phospholipid (PL). Based on phenotypic, genotypic and chemotaxonomic characteristics, two novel species are proposed, Oceanobacillus piezotolerans sp. nov. with YLB-02T (=MCCC 1A12699T=JCM 32870T) and Bacillus piezotolerans sp. nov. with YLB-04T (=MCCC 1A12711T=JCM 32872T) as the type strains.

9.
Bioresour Technol ; 290: 121776, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31302462

RESUMO

Deterioration of anaerobic digestion can occur with the presence of polyacrylamide (PAM) in waste activated sludge, but the information on alleviating this deterioration is still limited. In this study, the simultaneous alleviation of negative effect of PAM and improvement of methane production during anaerobic digestion was accomplished by microwave pretreatment. Experimental results showed that with the microwave pretreatment times increased from 0 to 12 min, the biochemical methane potential of PAM-flocculated sludge (12 g PAM/kg total solids) asymptotically increased from 123.1 to 242.5 mL/g volatile solids, hydrolysis rate increased from 0.06 to 0.13 d-1. Mechanism analysis indicated that the microwave pretreatment accelerated the release and hydrolysis of organic substrates from PAM-flocculated sludge, facilitated the breaking of large firm "PAM-sludge" floccules, and benefited the degradation of PAM, which alleviated the PAM inhibitory impacts on digestion and meanwhile provided better contact between the released organic substrates and anaerobic bacteria for methane production.

10.
Bioresour Technol ; 290: 121771, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31302468

RESUMO

In this work, a novel flocculation process by using nano-Fe3O4 coated with polyethyleneimine (Fe3O4@PEI) as magnetic seeds was developed to harvest the microalgae cultivated in urban sewage. Experiment results indicated that the harvest efficiency of Chlorella pyrenoidosa (0.5 g/L) was 98.92 ±â€¯0.41% under the optimal conditions of Fe3O4@PEI dose of 20 mL/L, flocculation time of 20 min, and stirring speed of 800 rpm (3 min), while that of Scenedesmus obliquus (0.4 g/L) was 98.45 ±â€¯0.35% under a Fe3O4@PEI dose of 16 mL/L, flocculation time of 15 min, and stirring speed of 730 rpm (3 min). Moreover, the process did not reduce the lipid content of microalgae and quality of biodiesel. After microalgae harvest, Fe3O4@PEI could be recovered by ultrasonication, re-wrapped with polyethyleneimine and reused to reduce operational cost.

11.
Genome Biol ; 20(1): 136, 2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31300020

RESUMO

BACKGROUND: Bread wheat is one of the most important and broadly studied crops. However, due to the complexity of its genome and incomplete genome collection of wild populations, the bread wheat genome landscape and domestication history remain elusive. RESULTS: By investigating the whole-genome resequencing data of 93 accessions from worldwide populations of bread wheat and its diploid and tetraploid progenitors, together with 90 published exome-capture data, we find that the B subgenome has more variations than A and D subgenomes, including SNPs and deletions. Population genetics analyses support a monophyletic origin of domesticated wheat from wild emmer in northern Levant, with substantial introgressed genomic fragments from southern Levant. Southern Levant contributes more than 676 Mb in AB subgenomes and enriched in the pericentromeric regions. The AB subgenome introgression happens at the early stage of wheat speciation and partially contributes to their greater genetic diversity. Furthermore, we detect massive alien introgressions that originated from distant species through natural and artificial hybridizations, resulting in the reintroduction of ~ 709 Mb and ~ 1577 Mb sequences into bread wheat landraces and varieties, respectively. A large fraction of these intra- and inter-introgression fragments are associated with quantitative trait loci of important traits, and selection events are also identified. CONCLUSION: We reveal the significance of multiple introgressions from distant wild populations and alien species in shaping the genetic components of bread wheat, and provide important resources and new perspectives for future wheat breeding.


Assuntos
Evolução Biológica , Variação Genética , Genoma de Planta , Hibridização Genética , Triticum/genética , Cromossomos de Plantas , Domesticação , Sequenciamento Completo do Genoma
12.
Chemosphere ; 235: 814-824, 2019 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-31280050

RESUMO

In this work, a low-cost alternative method (i.e., adding nitrate into WAS) to significantly enhance hydrogen production was reported. Experimental results showed that with an increase of nitrate addition from 0 to 362 mg/L, the maximal hydrogen production from acidic (pH 5.5) fermentation of WAS obviously increased from 12.6 ±â€¯0.5 to 19.3 ±â€¯0.9 mL per gram volatile suspended solids (VSS). The mechanism investigations illustrated more substrates were provided for subsequent hydrogen production. Although the nitrate added inhibited all the biological processes, its inhibition to the hydrogen consumption processes was much severer than that to the hydrogen production processes. The enzyme analyses on the long-term semi-continuous fermenters showed that the nitrate addition slightly inhibited the relative activities of protease, butyrate kinase, acetate kinase, CoA-transferase, and [FeFe] hydrogenase but largely suppressed the relative activities of coenzyme F420, carbon monoxide dehydrogenase, and adenylyl sulfate reductase.

13.
Water Res ; 162: 269-275, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31280085

RESUMO

Anaerobic methane generation from algae is hindered by the slow and poor algae biodegradability. A novel free ammonia (NH3 i.e. FA) pretreatment technology was proposed in this work to enhance anaerobic methane generation from algae cultivated using a real secondary effluent. The algae solubilisation was 0.05-0.06 g SCOD/g TCOD (SCOD: soluble chemical oxygen demand; TCOD: total chemical oxygen demand) following FA pretreatment of 240-530 mg NH3-N/L for 24 h, whereas the solubilisation was only 0.01 g SCOD/g TCOD for the untreated algae. This indicates that FA pretreatment at 240-530 mg NH3-N/L could substantially enhance algae solubilisation. Biochemical methane potential tests revealed that FA pretreatment on algae at 240-530 mg NH3-N/L is able to significantly enhance anaerobic methane generation. The hydrolysis rate (k) and biochemical methane potential (P0) of algae increased from 0.21 d-1 and 132 L CH4/kg TCOD to 0.33-0.50 d-1 and 140-154 L CH4/kg TCOD, respectively, after the algae was pretreated by FA at 240-530 mg NH3-N/L. Further analysis indicated that FA pretreatment improved k of both quickly and slowly biodegradable substrates, and also increased P0 of the slowly biodegradable substrate although it negatively affected P0 of the quickly biodegradable substrate. This FA technology is a closed-loop technology.

14.
Water Res ; 162: 331-338, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31288143

RESUMO

Sidestream sludge treatment approaches have been developed in recent years to achieve mainstream nitrite shunt or partial nitritation, where NOB are selectively inactivated by biocidal factors such as free nitrous acid (FNA) or free ammonium (FA) in a sidestream reactor. The existence of NOB in raw wastewater has been increasingly realized and could pose critical challenge to stable NOB suppressions in those systems. This study, for the first time, evaluated the impact of influent NOB on the NOB suppressions in a mainstream nitrite shunt system achieved through sidestream sludge treatment. An over 500-day sequential batch reactor operation with six experimental phases rigorously demonstrated the negative effects of influent NOB on mainstream NOB control. Continuously seeding of NOB contained in influent stimulated NOB community shifts, leading to different extents of ineffective NOB suppression. The role of primary wastewater treatment in NOB removal from raw wastewater was also investigated. Results suggest primary settling and High Rate Activated Sludge system could remove a large part of NOB contained in raw wastewater. Primary treatment for raw wastewater is necessary for ensuring stable mainstream NOB suppressions.

15.
Chemosphere ; 232: 45-53, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31152902

RESUMO

Aerobic digestion followed by dewatering is a widely applied method for sludge stabilization and reduction in decentralized wastewater treatment plants. It is important to enhance the sludge dewaterability of the aerobically digested sludge due to its considerable impact on cost of sludge disposal and management. In this study, an innovative technique is developed for improving the dewaterability of aerobically digested sludge by combined conditioning with persulfate (PS) and zero valent iron (ZVI). The results demonstrated that the dewaterability of aerobically digested sludge could be significantly enhanced with the PS and ZVI dosage in the range of 0-0.5 g/gTS and 0-0.4 g/gTS, respectively. The highest improvement was achieved at 0.05 g ZVI/g TS with 0.1 g PS/g TS, and the capillary suction time was reduced by ∼80%. The extracellular polymeric substances (EPS) characterization revealed that the combined PS-ZVI treatment could largely reduce proteins, polysaccharides and humic acids-like compounds in the tightly bounded EPS of the aerobically digested sludge, leading to bound water releasing from sludge flocs. The recovery of the ZVI particles could reach around 45%-80% after the treatment, further proved the sustainability of the approach. The proposed PS-ZVI conditioning would not have significant impact on the final choice of sludge disposal and the mainstream wastewater treatment. However, plant-scale test are still required for better assessing the proposed technique.


Assuntos
Ferro/química , Sulfatos/química , Eliminação de Resíduos Líquidos , Oxirredução , Esgotos , Águas Residuárias , Água
16.
Environ Pollut ; 252(Pt B): 1225-1234, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252120

RESUMO

Estuaries are considered hot spots for the production and emissions of nitrous oxide (N2O) and easily occur suspended particles (SPS), however, current understanding about the role of SPS in the N2O emissions from the oxic estuarine waters of lacustrine ecosystems is still limited. In this study, field investigations were performed in the estuaries of hypereutrophic Taihu Lake, and laboratory simulations were simultaneously conducted to ascertain the characteristics of N2O emissions with different SPS concentrations. The results showed that the N2O emission fluxes ranged from 9.75 to 118.38 µg m-2 h-1, indicating a high spatial heterogeneity for the N2O emissions from the estuaries of Taihu Lake. Although the dissolved oxygen (DO) concentrations were up to 7.85 mg L-1 in the estuarine waters, from where the N2O emissions fluxes were approximately three times that of the lake regions. Multiple regression model selected the total nitrogen (TN), SPS, and DO concentrations as the crucial factors influencing the N2O emission fluxes. Particularly for SPS, the simulation results showed that the N2O concentrations increased gradually with the increase in the SPS concentrations of an oxic water column containing 4 mg L-1 of NO3--N, indicating that a high SPS concentration can accelerate the N2O emissions. It was related to the change of denitrifying bacteria population in the SPS, as evidenced by its significantly positive correlation with N2O emissions (p < 0.01). Our findings will draw attentions to the role of SPS playing in the N2O productions and emissions in eutrophic lakes, and its effect on nitrogen cycle should be considered in the future study.

17.
Water Res ; 160: 339-349, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31158616

RESUMO

The wide application of chlorine disinfectant for drinking water treatment has led to the appearance of chlorine-resistant bacteria, which pose a severe threat to public health. This study was performed to explore the physiological-biochemical characteristics and environmental influence (pH, temperature, and turbidity) of seven strains of chlorine-resistant bacteria isolated from drinking water. Ozone disinfection was used to investigate the inactivation effect of bacteria and spores. The DNA concentration and cell surface structure variations of typical chlorine-resistant spores (Bacillus cereus spores) were also analysed by real-time qPCR, flow cytometry, and scanning electron microscopy to determine their inactivation mechanisms. The ozone resistance of bacteria (Aeromonas jandaei < Vogesella perlucida < Pelomonas < Bacillus cereus < Aeromonas sobria) was lower than that of spores (Bacillus alvei < Lysinibacillus fusiformis < Bacillus cereus) at an ozone concentration of 1.5 mg/L. More than 99.9% of Bacillus cereus spores were inactivated by increasing ozone concentration and treatment duration. Moreover, the DNA content of Bacillus cereus spores decreased sharply, but approximately 1/4 of the target genes remained. The spore structure exhibited shrinkage and folding after ozone treatment. Both cell structures and gene fragments were damaged by ozone disinfection. These results showed that ozone disinfection is a promising method for inactivating chlorine-resistant bacteria and spores in drinking water.

18.
Environ Int ; 130: 104946, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252169

RESUMO

Aerobic granular sludge (AGS) is promising in wastewater treatment. However, the formation and existence of AGS under low organic loading rate (OLR) is still not fully understood due to a knowledge gap in the variations and correlations of N-acyl-homoserine lactones (AHLs), the microbial community, extracellular polymeric substances (EPS) and other physiochemical granule properties. This study comprehensively investigated the AHL-mediated quorum sensing (QS) and microbial community characters in the AGS fed with ammonium-rich wastewater under a low OLR of 0.15 kg COD (m3 d)-1. The results showed that the AGS appeared within 90 days, and the size of mature granules was over 700 µm with strong settleability and ammonium removal performance. More tightly-bound extracellular polysaccharide and tightly-bound extracelluar protein were produced in the larger AGS. C10-HSL and C12-HSL gradually became dominant in sludge, and short-chain AHLs dominated in water. EPS producers and autotrophic nitrifiers were successfully retained in the AGS under low OLR. AHL-mediated QS utilized C10-HSL, C12-HSL and 3OC6-HSL as the critical AHLs to regulate the TB-EPS in aerobic granulation, and autotrophic nitrifiers may perform interspecific communication with C10-HSL. The correlations of bacterial genera with AGS properties and AHLs were complex due to the dynamic fluctuations of microbial composition and other variable factors in the mixed-culture system. These findings confirmed the participation of AHL-mediated QS in the regulation of microbial community characters and AGS properties under low OLR, which may provide guidance for the operation of AGS systems under low OLR from a microbiological viewpoint.

19.
J Microbiol ; 57(7): 562-568, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31124045

RESUMO

A Gram-positive, aerobic, rod-shaped, spore-forming bacterium, designated YLB-03T, with peritrichous flagella was isolated from deep-sea sediment of the Yap Trench at a depth of 4435 m. The bacterium was found to be catalase-positive but oxidase-negative. Growth of this bacterium was observed at 15-50°C (optimum 37°C), pH 5-10.5 (optimum 7), 0-5% NaCl (optimum 1%, w/v) and 0.1-50 MPa (optimum 0.1 MPa). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YLB-03T was a member of the genus Lysinibacillus. Strain YLB-03T was closely related to Lysinibacillus sinduriensis BLB-1T and Lysinibacillus chungkukjangi 2RL3-2T (98.4%), Lysinibacillus halotolerans LAM-612T (98.0%), Lysinibacillus telephonicus KT735049T (97.5%), Lysinibacillus endophyticus C9T (97.5%), Lysinibacillus composti NCCP-36T and Lysinibacillus massiliensis 4400831T (97.3%). The ANI and the GGDC DNA-DNA hybridization estimate values between strain YLB-03T and closely related type strains were 73.7-76.3% and 34.7-38.7%, respectively. The principal fatty acids were anteiso-C15:0 and iso-C15:0. The G+C content of the chromosomal DNA was 39.6 mol%. The respiratory quinone was determined to be MK-7. The diagnostic amino acids in the cell wall peptidoglycan contained Lys-Asp (type A4α) and the cell-wall sugars were glucose and xylose. The polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and an unidentified phospholipid. The combined genotypic and phenotypic data showed that strain YLB-03T represents a novel species within the genus Lysinibacillus, for which the name Lysinibacillus yapensis sp. nov. is proposed, with the type strain YLB-03T (= MCCC 1A12698T = JCM 32871T).


Assuntos
Bacillaceae/classificação , Sedimentos Geológicos/microbiologia , Bacillaceae/genética , Bacillaceae/isolamento & purificação , Técnicas de Tipagem Bacteriana/métodos , Oceano Pacífico , Filogenia , RNA Ribossômico 16S/genética
20.
Chemosphere ; 230: 536-543, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31125882

RESUMO

Free nitrous acid (FNA) or freezing has been recently utilized as an efficient pretreatment method to increase short-chain fatty acids (SCFAs) yield from waste activated sludge (WAS) anaerobic fermentation (AF). But until now, the performances and mechanisms of the co-pretreatment for SCFAs production are unknown. This research aimed to investigate the AF mechanisms through studying its influence on sludge solubilization and related bioprocesses. WAS was pretreated for 48 h with FNA (1.07 mg N/L), freezing (-5 °C) and combination of FNA and freezing (0.53-2.13 mg N/L FNA at -5 °C), respectively, then conducted batch AF. Experimental results indicated that the optimal total SCFAs yield of 391.19 ± 5.54 mg COD/g VSS was achieved after 1.07 mg N/L FNA + freezing pretreatment at 9 days of AF, which was 2.2, 1.6 and 1.3-fold of the blank, freezing and FNA pretreated samples, respectively. The mechanisms analysis showed that co-pretreatment showed synergetic effects on sludge disintegration and solubilization, which could release more soluble substrates for SCFAs production. The co-pretreatment resulted in slight inhibition to hydrolysis and negligible inhibition to acidogenesis but severe inhibition to methanogenesis, maybe due to less endurance of methanogens.


Assuntos
Ácidos Graxos Voláteis/análise , Fermentação , Congelamento , Ácido Nitroso/química , Esgotos/química , Eliminação de Resíduos Líquidos/métodos , Anaerobiose , Hidrólise , Esgotos/microbiologia
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