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Bioresource Technology Jul 2024In this study, the possibility of an auto-aggregating bacterium Pseudomonas strain XL-2 with heterotrophic nitrification-aerobic denitrification capacity for improving...
Evaluation of aerobic granulation performance bioaugmented with the auto-aggregating bacterium Pseudomonas stutzeri strain XL-2 with heterotrophic nitrification-aerobic denitrification capacity.
In this study, the possibility of an auto-aggregating bacterium Pseudomonas strain XL-2 with heterotrophic nitrification-aerobic denitrification capacity for improving granulation and nitrogen removal was evaluated. The results showed that the supplementation of strain XL-2 promoted granulation, making R1 (experimental group with strain XL-2) dominated by granules at 14 d, which was 12 days earlier than R2 (control group without strain XL-2). This was attributed to the promotion of extracellular polymeric substances (EPS) secretion, particularly proteins by adding strain XL-2, thereby improving the hydrophobicity of sludge and altering the proteins secondary structures to facilitate aggregation. Meanwhile, adding strain XL-2 improved simultaneous nitrification and denitrification efficiency of R1. Microbial community analysis indicated that strain XL-2 successfully proliferated in aerobic granule sludge and might induce the enrichment of genera such as Flavobacterium and Paracoccus that were favorable for EPS secretion and denitrification, jointly promoting granulation and enhancing nitrogen removal efficiency.
Topics: Denitrification; Nitrification; Pseudomonas stutzeri; Aerobiosis; Sewage; Nitrogen; Heterotrophic Processes; Extracellular Polymeric Substance Matrix; Bioreactors
PubMed: 38777236
DOI: 10.1016/j.biortech.2024.130869 -
Environmental Research Aug 2024In order to evaluate the impact of salinity gradients on the aniline biodegradation system, six reactors at salinity concentrations (0%-5%) were established. The results...
In order to evaluate the impact of salinity gradients on the aniline biodegradation system, six reactors at salinity concentrations (0%-5%) were established. The results presented the salinity except for 5% imposed negligible effects on aniline degradation performance. Nitrification had prominent resistance to salinity (0%-1.5%) while were significantly restrained when salinity increased. The total nitrogen (TN) removal efficiency of Z4 (1.5%) was 20.5% higher than Z1 (0%) during the stable operation phase. Moreover, high throughput sequencing analysis showed that halophilic bacterium, such as Halomonas, Rhodococcus, remained greater survival advantages in high salinity system. The substantial enrichment of Flavobacterium, Dokdonella, Paracoccus observed in Z4 ensured its excellent nitrogen removal performance. The close cooperation among dominant functional bacteria was strengthened when salt content was below 1.5% while exceeding 1.5% led to the collapse of metabolic capacity through integrating the toxicity of aniline and high osmotic pressure.
Topics: Aniline Compounds; Biodegradation, Environmental; Water Pollutants, Chemical; Salt Stress; Bacteria; Bioreactors; Salinity
PubMed: 38762003
DOI: 10.1016/j.envres.2024.119162 -
Bioresource Technology Jun 2024The construction of aerobic denitrification (AD) systems in an antibiotic-stressed environment is a serious challenge. This study investigated strategy of cyclic stress... (Review)
Review
The construction of aerobic denitrification (AD) systems in an antibiotic-stressed environment is a serious challenge. This study investigated strategy of cyclic stress with concentration gradient (5-30 mg/L) of sulfamethoxazole (SMX) in a sequencing batch reactor (SBR), to achieve operation of AD. Total nitrogen removal efficiency of system increased from about 10 % to 95 %. Original response of abundant-rare genera to antibiotics was changed by SMX stress, particularly conditionally rare or abundant taxa (CRAT). AD process depends on synergistic effect of heterotrophic nitrifying aerobic denitrification bacteria (Paracoccus, Thauera, Hypomicrobium, etc). AmoABC, napA, and nirK were functionally co-expressed with multiple antibiotic resistance genes (ARGs) (acrR, ereAB, and mdtO), facilitating AD process. ARGs and TCA cycling synergistically enhance the antioxidant and electron transport capacities of AD process. Antibiotic efflux pump mechanism played an important role in operation of AD. The study provides strong support for regulating activated sludge to achieve in situ AD function.
Topics: Denitrification; Sulfamethoxazole; Bioreactors; Aerobiosis; Sewage; Anti-Bacterial Agents; Nitrogen; Bacteria; Stress, Physiological
PubMed: 38710419
DOI: 10.1016/j.biortech.2024.130801 -
Journal of Advanced Veterinary and... Mar 2024The objectives of this study were to determine the richness, abundance, and diversity of bacteria in stray dogs () infested by ticks in Comarca Lagunera, northern...
OBJECTIVE
The objectives of this study were to determine the richness, abundance, and diversity of bacteria in stray dogs () infested by ticks in Comarca Lagunera, northern Mexico, and to establish their pathogenic and or/zoonotic potential.
MATERIALS AND METHODS
Blood samples from 12 dogs were collected, and their deoxyribonucleic acid was extracted. The V3-V4 region of the 16S ribosomal ribunocleic acid gene was amplified by polymerase chain reaction. Next-generation sequencing (NGS) was performed on a MiSeq Illumina platform, and the data were analyzed using quantitative insights into microbial ecology.
RESULTS
The operational taxonomic units resulted in 23 phyla, 54 classes, 89 orders, 189 families, 586 genera, and 620 bacterial species; among them, 64 species and/or bacterial genera with pathogenic or zoonotic potential were identified, some of which have been reported in the literature as relevant to public health ( spp spp spp spp spp spp spp and ).
CONCLUSION
This research offers relevant information on the prevalence of tick-borne diseases as well as other potential zoonotic diseases in the blood of stray dogs parasitized by ticks in northern Mexico. New molecular biology and massive NGS techniques may play an important role in the study and documentation of bacterial profiles from animals in close proximity to humans.
PubMed: 38680790
DOI: 10.5455/javar.2024.k757 -
Bioresource Technology Jun 2024Acetaminophen (APAP) is a frequently used, over-the-counter analgesic and antipyretic medication. Considering increase in global consumption, its ubiquity in environment...
Acetaminophen (APAP) is a frequently used, over-the-counter analgesic and antipyretic medication. Considering increase in global consumption, its ubiquity in environment with potential toxic impacts has become a cause of great concern. Hence, bioremediation of this emerging contaminant is of paramount significance. The present study incorporates a microcosm centric omics approach to gain in-depth insights into APAP degradation by Paracoccus sp. APAP_BH8. It can metabolize APAP (300 mg kg) within 16 days in soil microcosms. Genome analysis revealed potential genes capable of mediating degradation includes M20 aminoacylase family protein, guanidine deaminase, 4-hydroxybenzoate 3-monooxygenase, and 4-hydroxyphenylpyruvate dioxygenase. Whole proteome analysis showed differential expression of enzymes and bioinformatics provided evidence for stable binding of intermediates at the active site of considered enzymes. Metabolites identified were 4-aminophenol, hydroquinone, and 3-hydroxy-cis, cis-muconate. Therefore, Paracoccus sp. APAP_BH8 with versatile enzymatic and genetic attributes can be a promising candidate for formulating improved in situ APAP bioremediation strategies.
Topics: Acetaminophen; Biodegradation, Environmental; Proteomics; Genomics; Paracoccus; Metabolomics; Proteome
PubMed: 38677386
DOI: 10.1016/j.biortech.2024.130732 -
Biodegradation Apr 2024Pretilachlor and safener fenclorim are the main components of herbicides widely applied to control weeds. Although some pure cultures of bacteria and fungi which...
Pretilachlor and safener fenclorim are the main components of herbicides widely applied to control weeds. Although some pure cultures of bacteria and fungi which degraded these compounds under aerobic conditions were isolated, no isolated pretilachlor- and fenclorim-degrading bacterial strains under anaerobic condition had been available. In this study, the degradation of these compounds and the effects of them on bacterial community structures were investigated under anaerobic conditions. The dissipation rates of pretilachlor and fenclorim in slurries were in the order: soil from paddy field ≈ sediment from river > sediment from mangrove. Moreover, three pretilachlor-degrading bacterial strains (Pseudomonas sp. Pr1, Proteiniclasticum sp. Pr2 and Paracoccus denitrificans Pr3) and two fenclorim-degrading strains (Dechloromonas sp. Fe1 and Ralstonia pickettii Fe2) isolated from a slurry of paddy soil utilized the substrates as sole carbon and energy sources under anaerobic conditions. The degradation of pure pretilachlor and fenclorim at various concentrations by corresponding mixed pure cultures followed the Michaelis-Menten model, with the maximum degradation was 3.10 ± 0.31 µM/day for pretilachlor, and 2.08 ± 0.18 µM/day for fenclorim. During the degradation, 2-chloro-N-(2,6-diethylphenyl) acetamide and 2,6-dimethylaniline were produced in pretilachlor degradation, and benzene was a product of fenclorim degradation. The synergistic degradation of both substrates by all isolated bacteria reduced the metabolites concentrations accumulated in media. This study provides valuable information on effects of pretilachlor and fenclorim on bacterial communities in soil and sediments, and degradation of these substrates by isolated bacteria under anaerobic condition.
PubMed: 38662140
DOI: 10.1007/s10532-024-10078-1 -
Microbiology Spectrum Jun 2024In the nitrogen biogeochemical cycle, the reduction of nitrous oxide (NO) to N by NO reductase, which is encoded by gene, is the only biological pathway for NO...
UNLABELLED
In the nitrogen biogeochemical cycle, the reduction of nitrous oxide (NO) to N by NO reductase, which is encoded by gene, is the only biological pathway for NO consumption. In this study, we successfully isolated a strain of denitrifying R-1 from sewage treatment plant sludge. This strain has strong NO reduction capability, and the average NO reduction rate was 5.10 ± 0.11 × 10 µmol·h·cell under anaerobic condition in a defined medium. This reduction was accompanied by the stoichiometric consumption of acetate over time when NO served as the sole electron acceptor and the reduction can yield energy to support microbial growth, suggesting that microbial NO reduction is related to the energy generation process. Genomic analysis showed that the gene cluster encoding NO reductase of R-1 was composed of R, Z, D, F, Y, L, and Z, which was identified as that in other strains in clade I. Respiratory inhibitors test indicated that the pathway of electron transport for NO reduction was different from that of the traditional electron transport chain for aerobic respiration. Cu, silver nanoparticles, O, and acidic conditions can strongly inhibit the reduction, whereas NO or NH can promote it. These findings suggest that modular NO reduction of R-1 is linked to the electron transport and energy conservation, and dissimilatory NO reduction is a form of microbial anaerobic respiration.
IMPORTANCE
Nitrous oxide (NO) is a potent greenhouse gas and contributor to ozone layer destruction, and atmospheric NO has increased steadily over the past century due to human activities. The release of NO from fixed N is almost entirely controlled by microbial NO reductase activities. Here, we investigated the ability to obtain energy for the growth of R-1 by coupling the oxidation of various electron donors to NO reduction. The modular NO reduction process of denitrifying microorganism not only can consume NO produced by itself but also can consume the external NO generated from biological or abiotic pathways under suitable condition, which should be critical for controlling the release of NO from ecosystems into the atmosphere.
Topics: Paracoccus denitrificans; Nitrous Oxide; Electron Transport; Denitrification; Oxidoreductases; Oxidation-Reduction; Sewage; Bacterial Proteins; Electrons
PubMed: 38647341
DOI: 10.1128/spectrum.03811-23 -
Archives of Biochemistry and Biophysics Jun 2024Paracoccus denitrificans has a classical cytochrome-dependent electron transport chain and two alternative oxidases. The classical transport chain is very similar to...
Paracoccus denitrificans has a classical cytochrome-dependent electron transport chain and two alternative oxidases. The classical transport chain is very similar to that in eukaryotic mitochondria. Thus, P. denitrificans can serve as a model of the mammalian mitochondrion that may be more tractable in elucidating mechanisms of regulation of energy production than are mitochondria. In a previous publication we reported detailed studies on respiration in P. denitrificans grown aerobically on glucose or malate. We noted that P. denitrificans has large stores of lactate under various growth conditions. This is surprising because P. denitrificans lacks an NAD-dependent lactate dehydrogenase. The aim of this study was to investigate the mechanisms of lactate oxidation in P. denitrificans. We found that the bacterium grows well on either d-lactate or l-lactate. Growth on lactate supported a rate of maximum respiration that was equal to that of cells grown on glucose or malate. We report proteomic, metabolomic, and biochemical studies that establish that the metabolism of lactate by P. denitrificans is mediated by two non-NAD-dependent lactate dehydrogenases. One prefers d-lactate over l-lactate (D-iLDH) and the other prefers l-lactate (L-iLDH). We cloned and produced the D-iLDH and characterized it. The K for d-lactate was 34 μM, and for l-lactate it was 3.7 mM. Pyruvate was not a substrate, rendering the reaction unidirectional with lactate being converted to pyruvate for entry into the TCA cycle. The intracellular lactate was ∼14 mM such that both isomers could be metabolized by the enzyme. The enzyme has 1 FAD per molecule and utilizes a quinone rather than NAD as an electron acceptor. D-iLDH provides a direct entry of lactate reducing equivalents into the cytochrome chain, potentially explaining the high respiratory capacity of P. denitrificans in the presence of lactate.
Topics: Paracoccus denitrificans; Oxidation-Reduction; Lactic Acid; Glucose
PubMed: 38631502
DOI: 10.1016/j.abb.2024.109988 -
Current Microbiology Apr 2024A novel Paracoccus-related strain, designated YLB-12, was isolated from a sediment sample from the tidal zone of Shapowei Port, Xiamen, Fujian Province, PR China. The...
A novel Paracoccus-related strain, designated YLB-12, was isolated from a sediment sample from the tidal zone of Shapowei Port, Xiamen, Fujian Province, PR China. The novel strain is a Gram-stain-negative, short, rod-shaped, nonmotile, catalase- and oxidase-positive strain that grows at 10-37 °C and pH 5.0-9.0 in the presence of 0-12.0% (w/v) NaCl. Phylogenetic analysis of the 16S rRNA gene sequences indicated that this strain belongs to the genus Paracoccus and that its highest sequence similarity was to Paracoccus homiensis DD-R11 (98.5%), followed by Paracoccus zeaxanthinifaciens ATCC 21588 (97.4%), Paracoccus rhizosphaerae LMG 26205 (97.2%), Paracoccus beibuensis CGMCC 1.7295 (97.1%) and Paracoccus halotolerans CFH 90064 (97.0%). The DNA‒DNA hybridization values between strain YLB-12 and the five closely related type strains ranged from 20.4 to 22.4%. The genomic G+C content of strain YLB-12 was 63.7%. In addition to diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and phosphatidylglycerol, the polar lipids of the strain YLB-12 also consisted of an unidentified glycolipid and four unidentified polar lipids. The cells contained summed feature 8 (Cω6c /Cω7c, 62.7%) as the major cellular fatty acid and ubiquinone-10 as the predominant menaquinone. On the basis of its phenotypic and genotypic characteristics, strain YLB-12 represents a novel species within the genus Paracoccus, for which the name Paracoccus maritimus sp. nov. is proposed. The type strain was YLB-12 (= MCCC 1A17213 = KCTC 82197).
Topics: Phylogeny; RNA, Ribosomal, 16S; Fatty Acids; Paracoccus; DNA
PubMed: 38592513
DOI: 10.1007/s00284-024-03637-5 -
The Science of the Total Environment Jun 2024Until now, bacteria able to degrade, 3,3'-iminodipropionitrile (IDPN), a neurotoxin that destroys vestibular hair cells, causing ototoxicity, culminating in irreversible...
Until now, bacteria able to degrade, 3,3'-iminodipropionitrile (IDPN), a neurotoxin that destroys vestibular hair cells, causing ototoxicity, culminating in irreversible movement disorders, had never been isolated. The aim of this study was to isolate a novel IDPN-biodegrading microorganism and characterize its metabolic pathway. Enrichment was performed by inoculating activated sludge from a wastewater treatment bioreactor that treated IDPN-contaminated wastewater in M9 salt medium, with IDPN as the sole carbon source. A bacterial strain with a spherical morphology that could grow at high concentrations was isolated on a solid medium. Growth of the isolated strain followed the Monod kinetic model. Based on the 16S rRNA gene, the isolate was Paracoccus communis. Whole-genome sequencing revealed that the isolated P. communis possessed the expected full metabolic pathway for IDPN biodegradation. Transcriptome analyses confirmed the overexpression of the gene encoding hydantoinase/oxoprolinase during the exponential growth phase under IDPN-fed conditions, suggesting that the enzyme involved in cleaving the imine bond of IDPN may promote IDPN biodegradation. Additionally, the newly discovered P. communis isolate seems to metabolize IDPN through cleavage of the imine bond in IDPN via nitrilase, nitrile hydratase, and amidase reactions. Overall, this study lays the foundation for the application of IDPN-metabolizing bacteria in the remediation of IDPN-contaminated environments.
Topics: Nitriles; Bioreactors; Wastewater; Biodegradation, Environmental; Paracoccus; Waste Disposal, Fluid; Water Pollutants, Chemical; RNA, Ribosomal, 16S
PubMed: 38580115
DOI: 10.1016/j.scitotenv.2024.172099