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John W Foster - One of the best experts on this subject based on the ideXlab platform.
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acid resistance Systems required for survival of escherichia coli o157 h7 in the bovine gastrointestinal tract and in apple cider Are different
Applied and Environmental Microbiology, 2004Co-Authors: Stuart Price, James C Wright, Fred J Degraves, Mariepierre Castaniecornet, John W FosterAbstract:Escherichia coli O157:H7 is a highly acid-resistant food-borne pathogen that survives in the bovine and human gastrointestinal tracts and in acidic foods such as apple cider. This property is thought to contribute to the low infectious dose of the organism. Three acid resistance (Ar) Systems Are expressed in stationAry-phase cells. Ar System 1 is σS dependent, while Ar Systems 2 and 3 Are glutamate and Arginine dependent, respectively. In this study, we sought to determine which Ar Systems Are important for survival in acidic foods and which Are required for survival in the bovine intestinal tract. Wild-type and mutant E. coli O157:H7 strains deficient in Ar System 1, 2, or 3 were challenged with apple cider and inoculated into calves. Wild-type cells, adapted at pH 5.5 in the absence of glucose (Ar System 1 induced), survived well in apple cider. Conversely, the mutant deficient in Ar System 1, shown previously to survive poorly in calves, was susceptible to apple cider (pH 3.5), and this sensitivity was shown to be caused by low pH. Interestingly, the Ar System 2-deficient mutant survived in apple cider at high levels, but its shedding from calves was significantly decreased compAred to that of wild-type cells. Ar System 3-deficient cells survived well in both apple cider and calves. Taken together, these results indicate that E. coli O157:H7 utilizes different acid resistance Systems based on the type of acidic environment encountered.
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control of acid resistance in escherichia coli
Journal of Bacteriology, 1999Co-Authors: Mariepierre Castaniecornet, Dean K Smith, John F Elliott, Thomas Penfound, John W FosterAbstract:Acid resistance (Ar) in Escherichia coli is defined as the ability to withstand an acid challenge of pH 2.5 or less and is a trait generally restricted to stationAry-phase cells. EArlier reports described three Ar Systems in E. coli. In the present study, the genetics and control of these three Systems have been more cleArly defined. Expression of the first Ar System (designated the oxidative or glucose-repressed Ar System) was previously shown to require the alternative sigma factor RpoS. Consistent with glucose repression, this System also proved to be dependent in many situations on the cyclic AMP receptor protein. The second Ar System required the addition of Arginine during pH 2.5 acid challenge, the structural gene for Arginine decArboxylase (adiA), and the regulator cysB, confirming eArlier reports. The third Ar System required glutamate for protection at pH 2.5, one of two genes encoding glutamate decArboxylase (gadA or gadB), and the gene encoding the putative glutamate:γ-aminobutyric acid antiporter (gadC). Only one of the two glutamate decArboxylases was needed for protection at pH 2.5. However, survival at pH 2 required both glutamate decArboxylase isozymes. StationAry phase and acid pH regulation of the gad genes proved sepArable. StationAry-phase induction of gadA and gadB required the alternative sigma factor ςS encoded by rpoS. However, acid induction of these enzymes, which was demonstrated to occur in exponential- and stationAry-phase cells, proved to be ςS independent. Neither gad gene required the presence of volatile fatty acids for induction. The data also indicate that Ar via the amino acid decArboxylase Systems requires more than an inducible decArboxylase and antiporter. Another surprising finding was that the ςS-dependent oxidative System, originally thought to be acid induced, actually proved to be induced following entry into stationAry phase regArdless of the pH. However, an inhibitor produced at pH 8 somehow interferes with the activity of this System, giving the illusion of acid induction. The results also revealed that the Ar System affording the most effective protection at pH 2 in complex medium (either Luria-Bertani broth or brain heArt infusion broth plus 0.4% glucose) is the glutamate-dependent GAD System. Thus, E. coli possesses three overlapping acid survival Systems whose vArious levels of control and differing requirements for activity ensure that at least one System will be available to protect the stationAry-phase cell under naturally occurring acidic environments.
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compArative analysis of extreme acid survival in salmonella typhimurium shigella flexneri and escherichia coli
Journal of Bacteriology, 1995Co-Authors: Jyhshiun Lin, In Soo Lee, J Frey, J L Slonczewski, John W FosterAbstract:Several members of the family Enterobacteriaceae were examined for differences in extreme acid survival strategies. A surprising degree of vAriety was found between three related genera. The minimum growth pH of Salmonella typhimurium was shown to be significantly lower (pH 4.0) than that of either Escherichia coli (pH 4.4) or Shigella flexneri (pH 4.8), yet E. coli and S. flexneri both survive exposure to lower pH levels (2 to 2.5) than S. typhimurium (pH 3.0) in complex medium. S. typhimurium and E. coli but not S. flexneri expressed low-pH-inducible log-phase and stationAry-phase acid tolerance response (ATR) Systems that function in minimal or complex medium to protect cells to pH 3.0. All of the organisms also expressed a pH-independent general stress resistance System that contributed to acid survival during stationAry phase. E. coli and S. flexneri possessed several acid survival Systems (termed acid resistance [Ar]) that were not demonstrable in S. typhimurium. These additional Ar Systems protected cells to pH 2.5 and below but required supplementation of minimal medium for either induction or function. One acid-inducible Ar System required oxidative growth in complex medium for expression but successfully protected cells to pH 2.5 in unsupplemented minimal medium, while two other Ar Systems important for fermentatively grown cells required the addition of either glutamate or Arginine during pH 2.5 acid challenge. The Arginine Ar System was only observed in E. coli and required stationAry-phase induction in acidified complex medium. The product of the adi locus, Arginine decArboxylase, was responsible for Arginine-based acid survival.
Takeshi Kurata - One of the best experts on this subject based on the ideXlab platform.
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personal positioning based on walking locomotion analysis with self contained sensors and a weArable camera
International Symposium on Mixed and Augmented Reality, 2003Co-Authors: Masakatsu Kourogi, Takeshi KurataAbstract:In this paper, we propose a method of personal positioning for a weArable augmented reality (Ar) System that allows a user to freely move Around indoors and outdoors. The user is equipped with self-contained sensors, a weArable camera, an inertial head tracker and display. The method is based on sensor fusion of estimates for relative displacement caused by human walking locomotion and estimates for absolute position and orientation within a Kalman filtering framework. The former is based on intensive analysis of human walking behavior using self-contained sensors. The latter is based on image matching of video frames from a weArable camera with an image database that was prepAred beforehand.
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A weArable augmented reality System with personal positioning based on walking locomotion analysis
The Second IEEE and ACM International Symposium on Mixed and Augmented Reality, 2003. Proceedings., 2003Co-Authors: Masakatsu Kourogi, Takeshi KurataAbstract:In this paper, we present a weArable augmented reality (Ar) System with personal positioning based on walking locomotion analysis that allows a user to freely mover Around indoors and outdoors. The user is equipped with self-contained sensors, a weArable camera, an inertial head tracker and display. The System is based on the sensor fusion of estimates for relative displacement caused by human walking locomotion and estimates for absolute position and orientation within a Kalman filtering framework. The former is based on intensive analysis of human walking behavior using self-contained sensors. The latter is based on image matching of video frames from a weArable camera with an image database that was prepAred beforehand.
Masakatsu Kourogi - One of the best experts on this subject based on the ideXlab platform.
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personal positioning based on walking locomotion analysis with self contained sensors and a weArable camera
International Symposium on Mixed and Augmented Reality, 2003Co-Authors: Masakatsu Kourogi, Takeshi KurataAbstract:In this paper, we propose a method of personal positioning for a weArable augmented reality (Ar) System that allows a user to freely move Around indoors and outdoors. The user is equipped with self-contained sensors, a weArable camera, an inertial head tracker and display. The method is based on sensor fusion of estimates for relative displacement caused by human walking locomotion and estimates for absolute position and orientation within a Kalman filtering framework. The former is based on intensive analysis of human walking behavior using self-contained sensors. The latter is based on image matching of video frames from a weArable camera with an image database that was prepAred beforehand.
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A weArable augmented reality System with personal positioning based on walking locomotion analysis
The Second IEEE and ACM International Symposium on Mixed and Augmented Reality, 2003. Proceedings., 2003Co-Authors: Masakatsu Kourogi, Takeshi KurataAbstract:In this paper, we present a weArable augmented reality (Ar) System with personal positioning based on walking locomotion analysis that allows a user to freely mover Around indoors and outdoors. The user is equipped with self-contained sensors, a weArable camera, an inertial head tracker and display. The System is based on the sensor fusion of estimates for relative displacement caused by human walking locomotion and estimates for absolute position and orientation within a Kalman filtering framework. The former is based on intensive analysis of human walking behavior using self-contained sensors. The latter is based on image matching of video frames from a weArable camera with an image database that was prepAred beforehand.
Theodore T Tsotsis - One of the best experts on this subject based on the ideXlab platform.
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a reactive sepAration process for pre combustion co2 capture employing oxygen blown coal gasifier off gas
Chemical Engineering Journal, 2020Co-Authors: Mingyuan Cao, Linghao Zhao, Doug Parsley, Richard J Ciora, Paul K T Liu, Vasilios I Manousiouthakis, Theodore T TsotsisAbstract:Abstract We present here an experimental study of a reactive sepAration System, consisting of a membrane reactor (MR) and an adsorptive reactor (Ar) operating in tandem, with the MR’s reject stream serving as the Ar’s feed. We investigates the feasibility of applying this MR-Ar System for high-purity H2 production and simultaneous CO2 capture via the water gas shift (WGS) reaction in the context of Integrated Gas Combined Cycle (IGCC) power generation employing oxygen-blown gasifier syngas from biomass and coal. We previously studied this MR-Ar System for the IGCC process employing air-blown gasifier syngas, for which it demonstrated good performance, attaining high conversion exceeding equilibrium, producing ultra-pure H2 for power generation, and a CO2 stream ready for sequestration. In this study, we focus on oxygen-blown gasifier off-gas that contains no N2, with composition distinctly different from the air-blown gasifier syngas which has a lArge N2 content. We employ a cArbon moleculAr sieve membrane (CMSM), a commercial sour-shift WGS catalyst, and a hydrotalcite (HTC) adsorbent. We cArried out experiments to determine membrane performance and to identify promising operating conditions in an IGCC-relevant environment. The CMSM proved robust during a long-term (∼344 hr) experimental run under high temperature and pressure maintaining a high He/N2 selectivity (∼170). Multi-cycle runs were cArried out during which the MR-Ar System displayed superior performance to that of a packed bed reactor (PBR), by producing a H2 product with higher purity than that from the PBR which can be directly usable in power generation. Therefore, the findings from this study demonstrate the ability of the MR-Ar System to operate stably for a broad range of gasifier off-gas compositions, and indicate its potential for integration into IGCC plants for power generation with CO2 capture.
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a cArbon moleculAr sieve membrane based reactive sepAration process for pre combustion co2 capture
Journal of Membrane Science, 2020Co-Authors: Mingyuan Cao, Linghao Zhao, Richard J Ciora, Paul K T Liu, Vasilios I Manousiouthakis, Theodore T TsotsisAbstract:Abstract We discuss here a hybrid System combining a membrane reactor (MR) and an adsorptive reactor (Ar), with the MR's reject stream serving as the Ar's feed. We apply this System for the water gas shift (WGS) reaction for H2 generation and simultaneous CO2 capture in the context of the Integrated Gas Combined Cycle (IGCC) process for power generation from coal and biomass. This MR-Ar System attains a high conversion exceeding equilibrium, produces a pure H2 product for power generation, and delivers a high-pressure CO2 stream ready for sequestration. Specifically, in our study we use cArbon moleculAr sieve membranes (CMSMs) and a commercial sour-shift WGS catalyst. Lab experiments were cArried-out to determine the membrane chAracteristics, and the MR performance under IGCC-relevant conditions, i.e., for temperatures up to 250 °C and pressures up to 25 bAr, employing a model coal gasifier syngas. The CMSM and the catalyst have displayed robust and stable performance during a long-term run (~750 h of syngas exposure). We evaluated the MR-Ar System in multi-cycle runs and it has demonstrated superior performance to that of a conventional packed-bed reactor, producing a high-purity H2 product directly useable in a turbine for power generation. We conclude from the study, that the CMSM-based MR-Ar System is a good candidate technology for environmentally-benign power generation. We Are currently constructing a pilot-scale System for field demonstration of the technology.
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techno economic analysis of an intensified integrated gasification combined cycle igcc power plant featuring a combined membrane reactor adsorptive reactor mr Ar System
Industrial & Engineering Chemistry Research, 2020Co-Authors: Patricia Pichardo, Vasilios I Manousiouthakis, Theodore T Tsotsis, Secgin Karagoz, Rich CioraAbstract:In this work, the novel concept of a combined membrane–adsorptive reactor sequence (MR-Ar) is developed and implemented in an integrated gasification combined cycle (IGCC) plant. This novel MR-Ar I...
Mariepierre Castaniecornet - One of the best experts on this subject based on the ideXlab platform.
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acid resistance Systems required for survival of escherichia coli o157 h7 in the bovine gastrointestinal tract and in apple cider Are different
Applied and Environmental Microbiology, 2004Co-Authors: Stuart Price, James C Wright, Fred J Degraves, Mariepierre Castaniecornet, John W FosterAbstract:Escherichia coli O157:H7 is a highly acid-resistant food-borne pathogen that survives in the bovine and human gastrointestinal tracts and in acidic foods such as apple cider. This property is thought to contribute to the low infectious dose of the organism. Three acid resistance (Ar) Systems Are expressed in stationAry-phase cells. Ar System 1 is σS dependent, while Ar Systems 2 and 3 Are glutamate and Arginine dependent, respectively. In this study, we sought to determine which Ar Systems Are important for survival in acidic foods and which Are required for survival in the bovine intestinal tract. Wild-type and mutant E. coli O157:H7 strains deficient in Ar System 1, 2, or 3 were challenged with apple cider and inoculated into calves. Wild-type cells, adapted at pH 5.5 in the absence of glucose (Ar System 1 induced), survived well in apple cider. Conversely, the mutant deficient in Ar System 1, shown previously to survive poorly in calves, was susceptible to apple cider (pH 3.5), and this sensitivity was shown to be caused by low pH. Interestingly, the Ar System 2-deficient mutant survived in apple cider at high levels, but its shedding from calves was significantly decreased compAred to that of wild-type cells. Ar System 3-deficient cells survived well in both apple cider and calves. Taken together, these results indicate that E. coli O157:H7 utilizes different acid resistance Systems based on the type of acidic environment encountered.
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control of acid resistance in escherichia coli
Journal of Bacteriology, 1999Co-Authors: Mariepierre Castaniecornet, Dean K Smith, John F Elliott, Thomas Penfound, John W FosterAbstract:Acid resistance (Ar) in Escherichia coli is defined as the ability to withstand an acid challenge of pH 2.5 or less and is a trait generally restricted to stationAry-phase cells. EArlier reports described three Ar Systems in E. coli. In the present study, the genetics and control of these three Systems have been more cleArly defined. Expression of the first Ar System (designated the oxidative or glucose-repressed Ar System) was previously shown to require the alternative sigma factor RpoS. Consistent with glucose repression, this System also proved to be dependent in many situations on the cyclic AMP receptor protein. The second Ar System required the addition of Arginine during pH 2.5 acid challenge, the structural gene for Arginine decArboxylase (adiA), and the regulator cysB, confirming eArlier reports. The third Ar System required glutamate for protection at pH 2.5, one of two genes encoding glutamate decArboxylase (gadA or gadB), and the gene encoding the putative glutamate:γ-aminobutyric acid antiporter (gadC). Only one of the two glutamate decArboxylases was needed for protection at pH 2.5. However, survival at pH 2 required both glutamate decArboxylase isozymes. StationAry phase and acid pH regulation of the gad genes proved sepArable. StationAry-phase induction of gadA and gadB required the alternative sigma factor ςS encoded by rpoS. However, acid induction of these enzymes, which was demonstrated to occur in exponential- and stationAry-phase cells, proved to be ςS independent. Neither gad gene required the presence of volatile fatty acids for induction. The data also indicate that Ar via the amino acid decArboxylase Systems requires more than an inducible decArboxylase and antiporter. Another surprising finding was that the ςS-dependent oxidative System, originally thought to be acid induced, actually proved to be induced following entry into stationAry phase regArdless of the pH. However, an inhibitor produced at pH 8 somehow interferes with the activity of this System, giving the illusion of acid induction. The results also revealed that the Ar System affording the most effective protection at pH 2 in complex medium (either Luria-Bertani broth or brain heArt infusion broth plus 0.4% glucose) is the glutamate-dependent GAD System. Thus, E. coli possesses three overlapping acid survival Systems whose vArious levels of control and differing requirements for activity ensure that at least one System will be available to protect the stationAry-phase cell under naturally occurring acidic environments.