scholarly journals Efficient Metabolic Exchange and Electron Transfer within a Syntrophic Trichloroethene-Degrading Coculture of Dehalococcoides mccartyi 195 and Syntrophomonas wolfei

2015 ◽  
Vol 81 (6) ◽  
pp. 2015-2024 ◽  
Author(s):  
Xinwei Mao ◽  
Benoit Stenuit ◽  
Alexandra Polasko ◽  
Lisa Alvarez-Cohen
Keyword(s):  
Pure Culture ◽  
Threshold Value ◽  
Content Type ◽  
Dehalococcoides Mccartyi ◽  
Atp Binding Cassette Transporter ◽  
Syntrophomonas Wolfei ◽  
Membrane Bound ◽  
Butyrate Fermentation ◽  
20 Nm ◽  
Metabolic Exchange

ABSTRACTDehalococcoides mccartyi195 (strain 195) andSyntrophomonas wolfeiwere grown in a sustainable syntrophic coculture using butyrate as an electron donor and carbon source and trichloroethene (TCE) as an electron acceptor. The maximum dechlorination rate (9.9 ± 0.1 μmol day−1) and cell yield [(1.1 ± 0.3) × 108cells μmol−1Cl−] of strain 195 maintained in coculture were, respectively, 2.6 and 1.6 times higher than those measured in the pure culture. The strain 195 cell concentration was about 16 times higher than that ofS. wolfeiin the coculture. Aqueous H2concentrations ranged from 24 to 180 nM during dechlorination and increased to 350 ± 20 nM when TCE was depleted, resulting in cessation of butyrate fermentation byS. wolfeiwith a theoretical Gibbs free energy of −13.7 ± 0.2 kJ mol−1. Carbon monoxide in the coculture was around 0.06 μmol per bottle, which was lower than that observed for strain 195 in isolation. The minimum H2threshold value for TCE dechlorination by strain 195 in the coculture was 0.6 ± 0.1 nM. Cell aggregates during syntrophic growth were observed by scanning electron microscopy. The interspecies distances to achieve H2fluxes required to support the measured dechlorination rates were predicted using Fick's law and demonstrated the need for aggregation. Filamentous appendages and extracellular polymeric substance (EPS)-like structures were present in the intercellular spaces. The transcriptome of strain 195 during exponential growth in the coculture indicated increased ATP-binding cassette transporter activities compared to the pure culture, while the membrane-bound energy metabolism related genes were expressed at stable levels.

scholarly journals Methanobactin from Methylocystis sp. Strain SB2 Affects Gene Expression and Methane Monooxygenase Activity in Methylosinus trichosporium OB3b

2015 ◽  
Vol 81 (7) ◽  
pp. 2466-2473 ◽  
Author(s):  
Muhammad Farhan Ul-Haque ◽  
Bhagyalakshmi Kalidass ◽  
Alexey Vorobev ◽  
Bipin S. Baral ◽  
Alan A. DiSpirito ◽  
...  
Keyword(s):  
Gene Expression ◽  
Methane Monooxygenase ◽  
Particulate Methane Monooxygenase ◽  
Methylosinus Trichosporium Ob3b ◽  
Methylosinus Trichosporium ◽  
Monooxygenase Activity ◽  
Content Type ◽  
Soluble Methane Monooxygenase ◽  
A Subunit ◽  
Membrane Bound

ABSTRACTMethanotrophs can express a cytoplasmic (soluble) methane monooxygenase (sMMO) or membrane-bound (particulate) methane monooxygenase (pMMO). Expression of these MMOs is strongly regulated by the availability of copper. Many methanotrophs have been found to synthesize a novel compound, methanobactin (Mb), that is responsible for the uptake of copper, and methanobactin produced byMethylosinus trichosporiumOB3b plays a key role in controlling expression of MMO genes in this strain. As all known forms of methanobactin are structurally similar, it was hypothesized that methanobactin from one methanotroph may alter gene expression in another. WhenMethylosinus trichosporiumOB3b was grown in the presence of 1 μM CuCl2, expression ofmmoX, encoding a subunit of the hydroxylase component of sMMO, was very low.mmoXexpression increased, however, when methanobactin fromMethylocystissp. strain SB2 (SB2-Mb) was added, as did whole-cell sMMO activity, but there was no significant change in the amount of copper associated withM. trichosporiumOB3b. IfM. trichosporiumOB3b was grown in the absence of CuCl2, themmoXexpression level was high but decreased by several orders of magnitude if copper prebound to SB2-Mb (Cu-SB2-Mb) was added, and biomass-associated copper was increased. Exposure ofMethylosinus trichosporiumOB3b to SB2-Mb had no effect on expression ofmbnA, encoding the polypeptide precursor of methanobactin in either the presence or absence of CuCl2.mbnAexpression, however, was reduced when Cu-SB2-Mb was added in both the absence and presence of CuCl2. These data suggest that methanobactin acts as a general signaling molecule in methanotrophs and that methanobactin “piracy” may be commonplace.

scholarly journals Strain- and Substrate-Dependent Redox Mediator and Electricity Production by Pseudomonas aeruginosa

2016 ◽  
Vol 82 (16) ◽  
pp. 5026-5038 ◽  
Author(s):  
Erick M. Bosire ◽  
Lars M. Blank ◽  
Miriam A. Rosenbaum
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Electron Transfer ◽  
Fuel Cells ◽  
Microbial Fuel Cells ◽  
Pure Culture ◽  
Bioelectrochemical Systems ◽  
Content Type ◽  
Mediated Electron Transfer ◽  
Phenazine Production ◽  
Model Strain

ABSTRACTPseudomonas aeruginosais an important, thriving member of microbial communities of microbial bioelectrochemical systems (BES) through the production of versatile phenazine redox mediators. Pure culture experiments with a model strain revealed synergistic interactions ofP. aeruginosawith fermenting microorganisms whereby the synergism was mediated through the shared fermentation product 2,3-butanediol. Our work here shows that the behavior and efficiency ofP. aeruginosain mediated current production is strongly dependent on the strain ofP. aeruginosa. We compared levels of phenazine production by the previously investigated model strainP. aeruginosaPA14, the alternative model strainP. aeruginosaPAO1, and the BES isolatePseudomonassp. strain KRP1 with glucose and the fermentation products 2,3-butanediol and ethanol as carbon substrates. We found significant differences in substrate-dependent phenazine production and resulting anodic current generation for the three strains, with the BES isolate KRP1 being overall the best current producer and showing the highest electrochemical activity with glucose as a substrate (19 μA cm−2with ∼150 μg ml−1phenazine carboxylic acid as a redox mediator). Surprisingly,P. aeruginosaPAO1 showed very low phenazine production and electrochemical activity under all tested conditions.IMPORTANCEMicrobial fuel cells and other microbial bioelectrochemical systems hold great promise for environmental technologies such as wastewater treatment and bioremediation. While there is much emphasis on the development of materials and devices to realize such systems, the investigation and a deeper understanding of the underlying microbiology and ecology are lagging behind. Physiological investigations focus on microorganisms exhibiting direct electron transfer in pure culture systems. Meanwhile, mediated electron transfer with natural redox compounds produced by, for example,Pseudomonas aeruginosamight enable an entire microbial community to access a solid electrode as an alternative electron acceptor. To better understand the ecological relationships between mediator producers and mediator utilizers, we here present a comparison of the phenazine-dependent electroactivities of threePseudomonasstrains. This work forms the foundation for more complex coculture investigations of mediated electron transfer in microbial fuel cells.

scholarly journals Competition between Metals for Binding to Methanobactin Enables Expression of Soluble Methane Monooxygenase in the Presence of Copper

2014 ◽  
Vol 81 (3) ◽  
pp. 1024-1031 ◽  
Author(s):  
Bhagyalakshmi Kalidass ◽  
Muhammad Farhan Ul-Haque ◽  
Bipin S. Baral ◽  
Alan A. DiSpirito ◽  
Jeremy D. Semrau
Keyword(s):  
Methane Monooxygenase ◽  
High Specificity ◽  
Copper Uptake ◽  
Content Type ◽  
Soluble Methane Monooxygenase ◽  
Sds Page ◽  
Genes Encoding ◽  
Key Factor ◽  
Membrane Bound

ABSTRACTIt is well known that copper is a key factor regulating expression of the two forms of methane monooxygenase found in proteobacterial methanotrophs. Of these forms, the cytoplasmic, or soluble, methane monooxygenase (sMMO) is expressed only at low copper concentrations. The membrane-bound, or particulate, methane monooxygenase (pMMO) is constitutively expressed with respect to copper, and such expression increases with increasing copper. Recent findings have shown that copper uptake is mediated by a modified polypeptide, or chalkophore, termed methanobactin. Although methanobactin has high specificity for copper, it can bind other metals, e.g., gold. Here we show that inMethylosinus trichosporiumOB3b, sMMO is expressed and active in the presence of copper if gold is also simultaneously present. Such expression appears to be due to gold binding to methanobactin produced byM. trichosporiumOB3b, thereby limiting copper uptake. Such expression and activity, however, was significantly reduced if methanobactin preloaded with copper was also added. Further, quantitative reverse transcriptase PCR (RT-qPCR) of transcripts of genes encoding polypeptides of both forms of MMO and SDS-PAGE results indicate that both sMMO and pMMO can be expressed when copper and gold are present, as gold effectively competes with copper for binding to methanobactin. Such findings suggest that under certain geochemical conditions, both forms of MMO may be expressed and activein situ. Finally, these findings also suggest strategies whereby field sites can be manipulated to enhance sMMO expression, i.e., through the addition of a metal that can compete with copper for binding to methanobactin.

scholarly journals Why Orange Guaymas Basin Beggiatoa spp. Are Orange: Single-Filament-Genome-Enabled Identification of an Abundant Octaheme Cytochrome with Hydroxylamine Oxidase, Hydrazine Oxidase, and Nitrite Reductase Activities

2012 ◽  
Vol 79 (4) ◽  
pp. 1183-1190 ◽  
Author(s):  
Barbara J. MacGregor ◽  
Jennifer F. Biddle ◽  
Jason R. Siebert ◽  
Eric Staunton ◽  
Eric L. Hegg ◽  
...  
Keyword(s):  
Nitrite Reductase ◽  
Pure Culture ◽  
Gulf Of California ◽  
Microbial Mats ◽  
Physiological Role ◽  
Nitrite Reduction ◽  
Cold Seeps ◽  
Single Filament ◽  
Guaymas Basin ◽  
Content Type

ABSTRACTOrange, white, and yellow vacuolatedBeggiatoaceaefilaments are visually dominant members of microbial mats found near sea floor hydrothermal vents and cold seeps, with orange filaments typically concentrated toward the mat centers. No marine vacuolateBeggiatoaceaeare yet in pure culture, but evidence to date suggests they are nitrate-reducing, sulfide-oxidizing bacteria. The nearly complete genome sequence of a single orangeBeggiatoa(“CandidatusMaribeggiatoa”) filament from a microbial mat sample collected in 2008 at a hydrothermal site in Guaymas Basin (Gulf of California, Mexico) was recently obtained. From this sequence, the gene encoding an abundant soluble orange-pigmented protein in Guaymas Basin mat samples (collected in 2009) was identified by microcapillary reverse-phase high-performance liquid chromatography (HPLC) nano-electrospray tandem mass spectrometry (μLC–MS-MS) of a pigmented band excised from a denaturing polyacrylamide gel. The predicted protein sequence is related to a large group of octaheme cytochromes whose few characterized representatives are hydroxylamine or hydrazine oxidases. The protein was partially purified and shown byin vitroassays to have hydroxylamine oxidase, hydrazine oxidase, and nitrite reductase activities. From what is known ofBeggiatoaceaephysiology, nitrite reduction is the most likelyin vivorole of the octaheme protein, but future experiments are required to confirm this tentative conclusion. Thus, while present-day genomic and proteomic techniques have allowed precise identification of an abundant mat protein, and its potential activities could be assayed, proof of its physiological role remains elusive in the absence of a pure culture that can be genetically manipulated.

Rapid video assessment for monitoring testing facility fraud

2018 ◽  
Vol 35 (8) ◽  
pp. 1508-1518
Author(s):  
Rosembergue Pereira Souza ◽  
Luiz Fernando Rust da Costa Carmo ◽  
Luci Pirmez
Keyword(s):  
Processing Time ◽  
Threshold Value ◽  
Real World Data ◽  
Data Set ◽  
Content Type ◽  
Video Assessment ◽  
Technical Requirements ◽  
Testing Facility ◽  
Rapid Processing ◽  
Temporal Differencing

Purpose The purpose of this paper is to present a procedure for finding unusual patterns in accredited tests using a rapid processing method for analyzing video records. The procedure uses the temporal differencing technique for object tracking and considers only frames not identified as statistically redundant. Design/methodology/approach An accreditation organization is responsible for accrediting facilities to undertake testing and calibration activities. Periodically, such organizations evaluate accredited testing facilities. These evaluations could use video records and photographs of the tests performed by the facility to judge their conformity to technical requirements. To validate the proposed procedure, a real-world data set with video records from accredited testing facilities in the field of vehicle safety in Brazil was used. The processing time of this proposed procedure was compared with the time needed to process the video records in a traditional fashion. Findings With an appropriate threshold value, the proposed procedure could successfully identify video records of fraudulent services. Processing time was faster than when a traditional method was employed. Originality/value Manually evaluating video records is time consuming and tedious. This paper proposes a procedure to rapidly find unusual patterns in videos of accredited tests with a minimum of manual effort.

scholarly journals Perforin-2 Protects Host Cells and Mice by Restricting the Vacuole to Cytosol Transitioning of a Bacterial Pathogen

2016 ◽  
Vol 84 (4) ◽  
pp. 1083-1091 ◽  
Author(s):  
Ryan McCormack ◽  
Wael Bahnan ◽  
Niraj Shrestha ◽  
Justin Boucher ◽  
Marcella Barreto ◽  
...  
Keyword(s):  
Bacterial Pathogen ◽  
Virulence Gene ◽  
Systemic Infection ◽  
Protective Role ◽  
Host Cells ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Membrane Bound ◽  
High Level ◽  
Macpf Domain

The host-encoded Perforin-2 (encoded by the macrophage-expressed gene 1,Mpeg1), which possesses a pore-forming MACPF domain, reduces the viability of bacterial pathogens that reside within membrane-bound compartments. Here, it is shown that Perforin-2 also restricts the proliferation of the intracytosolic pathogenListeria monocytogenes. Within a few hours of systemic infection, the massive proliferation ofL. monocytogenesinPerforin-2−/−mice leads to a rapid appearance of acute disease symptoms. We go on to show in culturedPerforin-2−/−cells that the vacuole-to-cytosol transitioning ofL. monocytogenesis greatly accelerated. Unexpectedly, we found that inPerforin-2−/−macrophages,Listeria-containing vacuoles quickly (≤15 min) acidify, and that this was coincident with greater virulence gene expression, likely accounting for the more rapid translocation ofL. monocytogenesto its replicative niche in the cytosol. This hypothesis was supported by our finding that aL. monocytogenesstrain expressing virulence factors at a constitutively high level replicated equally well inPerforin-2+/+andPerforin-2−/−macrophages. Our findings suggest that the protective role of Perforin-2 against listeriosis is based on it limiting the intracellular replication of the pathogen. This cellular activity of Perforin-2 may derive from it regulating the acidification ofListeria-containing vacuoles, thereby depriving the pathogen of favorable intracellular conditions that promote its virulence gene activity.

scholarly journals Position of O-Acetylation within the Capsular Repeat Unit Impacts the Biological Properties of Pneumococcal Serotypes 33A and 33F

2017 ◽  
Vol 85 (7) ◽  
Author(s):  
Brady L. Spencer ◽  
Jamil S. Saad ◽  
Anukul T. Shenoy ◽  
Carlos J. Orihuela ◽  
Moon H. Nahm
Keyword(s):  
Cell Wall ◽  
Repeat Unit ◽  
Biological Properties ◽  
Immune Recognition ◽  
Content Type ◽  
Pneumococcal Serotype ◽  
Membrane Bound ◽  
Biochemical Analyses ◽  
Opsonophagocytic Killing ◽  
Small Chemical

ABSTRACT Streptococcus pneumoniae (pneumococcus) produces many capsule types that differ in their abilities to evade host immune recognition. To explain these serotype-dependent protective capacities, many studies have investigated capsular thickness or the interaction of the capsule with complement proteins, but the effects of small chemical modifications of the capsule on its function have not been studied. One small chemical modification found frequently among pneumococcal capsules is O-acetylation. Pneumococcal serotype 33A has two membrane-bound O-acetyltransferase genes, wciG and wcjE. A 33A wcjE-deficient variant, 33F, occurs naturally and is increasing in prevalence in the wake of widespread conjugate vaccine use, but no wciG-deficient variants have been reported. To study the biological consequence of the loss of O-acetylation, we created wciG-deficient variants in both serotypes 33A and 33F, which we named 33X1 (ΔwciG) and 33X2 (ΔwciG ΔwcjE). Serotypes 33X1 and 33X2 express novel capsule types based on serological and biochemical analyses. We found that loss of WcjE-mediated O-acetylation appears not to affect cell wall shielding, since serotypes 33A and 33F exhibit comparable nonspecific opsonophagocytic killing, biofilm production, and adhesion to nasopharyngeal cells, though serotype 33F survived short-term drying better than serotype 33A. Loss of WciG-mediated O-acetylation in serotypes 33X1 and 33X2, however, resulted in a phenotype resembling that of nonencapsulated strains: increased cell wall accessibility, increased nonspecific opsonophagocytic killing, enhanced biofilm formation, and increased adhesion to nasopharyngeal cells. We conclude that WciG-mediated, but not WcjE-mediated, O-acetylation is important for producing protective capsules in 33A and that small chemical changes to the capsule can drastically affect its biological properties.

scholarly journals Streptomyces barkulensis sp. nov., isolated from an estuarine lake

2014 ◽  
Vol 64 (Pt_4) ◽  
pp. 1365-1372 ◽  
Author(s):  
Lopamudra Ray ◽  
Samir Ranjan Mishra ◽  
Ananta Narayan Panda ◽  
Gurdeep Rastogi ◽  
Ajit Kumar Pattanaik ◽  
...  
Keyword(s):  
Type Species ◽  
Gene Sequence ◽  
Novel Species ◽  
Threshold Value ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type ◽  
Phyletic Line ◽  
Actinomycete Strain ◽  
Reference Strains

The taxonomic position of a novel actinomycete, strain RC 1831T, isolated from the sediment of a fish dumping yard at Barkul village near Chilika Lake, Odisha, India, was determined by a polyphasic approach. Based on morphological and chemotaxonomic characteristics the isolate was determined to belong to the genus Streptomyces . The phylogenetic tree based on its nearly complete 16S rRNA gene sequence (1428 nt) with representative strains showed that the strain consistently falls into a distinct phyletic line together with Streptomyces glaucosporus DSM 41689T (98.22 % similarity) and a subclade consisting of Streptomyces atacamensis DSM 42065T (98.40 %), Streptomyces radiopugnans R97 DSM 41901T (98.27 %), Streptomyces fenghuangensis GIMN4.003T (98.33 %), Streptomyces nanhaiensis DSM 41926T (98.13 %), Streptomyces megasporus NBRC 14749T (97.37 %) and Streptomyces macrosporus NBRC 14748T (98.22 %). However, the levels of DNA–DNA relatedness between strain RC 1831T and phylogenetically related strains Streptomyces atacamensis DSM 42065T (28.75±3.25 %) and Streptomyces glaucosporus DSM 41689T (15±2.40 %) were significantly lower than the 70 % threshold value for delineation of genomic species. Furthermore, the isolate could be distinguished phenotypically on the basis of physiological, morphological and biochemical differences from its closest phylogenetic neighbours and other related reference strains. Strain RC 1831T is therefore considered to represent a novel species of the genus Streptomyces , for which the name Streptomyces barkulensis sp. nov. is proposed. The type strain is RC 1831T ( = JCM 18754T = DSM 42082T).

A new method to optimize the truncated PCE order of collocation-based SRSM in reliability analysis and its application to geotechnical problems

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Peng Zeng ◽  
Tianbin Li ◽  
Rafael Jimenez ◽  
Xianda Feng ◽  
Yu Chen ◽  
...  
Keyword(s):  
Preliminary Test ◽  
Threshold Value ◽  
Selection Method ◽  
Optimal Order ◽  
Order Selection ◽  
Trade Off ◽  
Content Type ◽  
Selection Strategies ◽  
Practical Implications ◽  
Geotechnical Problems

PurposeThe collocation-based stochastic response surface method (CSRSM) is widely used in geotechnical reliability analyses due to its efficiency and accuracy. Determining the optimal truncated order of the associated polynomial chaos expansion (PCE) is important, as it may strongly affect the practical applicability of CSRSM.Design/methodology/approachThis study investigates the performance of different optimal order selection strategies used in the CSRSM and proposes a new cross-order validation method. First, several methods commonly used for optimal order selection are briefly reviewed, and their merits and limitations for reliability analyses are discussed. Then, an improved optimal order selection method that achieves a better trade-off between efficiency and accuracy is proposed.FindingsIn total, ten simple mathematical examples from the literature are employed to perform a preliminary test on the proposed method, and a comparative study is conducted to demonstrate its advantages with respect to some other existing methods.Practical implicationsA total of three typical geotechnical problems are employed to demonstrate the performance of the proposed method in geotechnical practice.Originality/valueAn improved optimal order selection method that achieves a better trade-off between efficiency and accuracy is proposed. The threshold value of the deterministic coefficient used for the proposed method is discussed.

A labelling system and automation comparison index for industry 4.0 system

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shailendra Kumar ◽  
Mohammad Asjad ◽  
Mohd. Suhaib
Keyword(s):  
Industry 4.0 ◽  
Manufacturing System ◽  
Threshold Value ◽  
Fuzzy Cognitive Maps ◽  
Automated System ◽  
Content Type ◽  
Level Of Automation ◽  
Industrial Sectors ◽  
Automation Level ◽  
Labelling System

Purpose This paper aims to put forward a labelling system capable of reflecting the level of different Industry 4.0 (I4.0)features present in a manufacturing system and further propose a comparative index to collectively estimate and compare the system automation level. Design/methodology/approach Data for the empirical study were collected from interactions with the practising managers and experts. A relationship among the six I4.0 features is developed with fuzzy cognitive maps. Findings The paper proposed a simple and easy-to-understand labelling system for I4.0 systems, which indicates the automation level in each of six dimensions of any manufacturing system. The system is further strengthened by a proposed automation comparative index (ACI), which collectively reflects the automation level on a scale of “0” to “1”. Thus, the labelling system and parameter could help in comparing the level of automation in the manufacturing system and further decision-making. Research limitations/implications Only seven industrial sectors are illustrated in the paper, but the proposed concept of the classification scheme and ACI find their applicability on a large spectrum of industries; thus, the concept can be extended to other industrial sectors. Furthermore, a threshold value of ACI is a differentiator between a I4.0 and other automated systems. Both aspects have the scope of further work. Practical implications The way and pace by which the industrial world takes forward the concept of I4.0, soon it will need a labelling system and a parameter to assess the automation level of any automated system. The scheme assesses the automation level present in a manufacturing system. It will also estimate the level of the presence of each of all six attributes of an I4.0 system. Both labelling system and ACI will be the practical tools in the hands of the practising managers to help compare, identify the thrust areas and make decisions accordingly. Originality/value To the best of the authors’ knowledge, this is the first study of its kind that proposed the labelling system and automation comparison index for I4.0 systems.

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