The base catalysed hydrolysis of methyl paraben: a test reaction for flow microcalorimeters used for determination of both kinetic and thermodynamic parameters

O'Neill, M; Beezer, Anthony E.; Labetoulle, Chloé; Nicolaides, Linda; Mitchell, John C.; Orchard, John E.; Connor, Joseph A.; Кемп, Р. Б.; Olomolaiye, D.

doi:10.1016/s0040-6031(02)00401-x

Cited by 47 publications

(35 citation statements)

References 10 publications

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“…It converts the heat generated by the bacteria inside the measurement chamber into a voltage signal. The average sensitivity is 8.3 V/W, as determined by a chemical calibration which was established for conventional microcalorimeters (23). The measurement chamber is made from polymethylmethacrylate (PMMA).…”

Section: Methodsmentioning

confidence: 99%

Chip Calorimetry for Fast and Reliable Evaluation of Bactericidal and Bacteriostatic Treatments of Biofilms

Buchholz

Wolf

Lerchner

et al. 2010

Antimicrob Agents Chemother

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Chip calorimetry is introduced as a new monitoring tool that provides real-time information about the physiological state of biofilms. Its potential for use for the study of the effects of antibiotics and other biocides was tested. Established Pseudomonas putida biofilms were exposed to substances known to cause toxicity by different mechanisms and to provoke different responses of defense and resistance. The effects of these compounds on heat production rates were monitored and compared with the effects of these compounds on the numbers of CFU and intracellular ATP contents. The real-time monitoring potential of chip calorimetry was successfully demonstrated by using as examples the fast-acting poisons formaldehyde and 2,4-dinitrophenol (DNP). A dosage of antibiotics initially increased the heat production rate. This was discussed as being the effect of energy-dependent resistance mechanisms (e.g., export and/or transformation of the antibiotic). The subsequent reduction in the heat production rate was attributed to the loss of activity and the death of the biofilm bacteria. The shapes of the death curves were in agreement with the assumed variation in the levels of exposure of cells within the multilayer biofilms. The new monitoring tool provides fast, quantitative, and mechanistic insights into the acute and chronic effects of a compound on biofilm activity while requiring only minute quantities of the biocide.

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Section: Methodsmentioning

confidence: 99%

Chip Calorimetry for Fast and Reliable Evaluation of Bactericidal and Bacteriostatic Treatments of Biofilms

Buchholz

Wolf

Lerchner

et al. 2010

Antimicrob Agents Chemother

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“…This was confirmed by our experimental finding that varying the pump rate between 30 and 120 cm 3 /h had negligible effects. Using the alkaline hydrolysis of methyl paraben for the chemical calibration (O'Neill et al, 2003(O'Neill et al, , 2004, the thermal sensitive volume was determined to be 0.51 cm 3 . All measurements were performed in the 3,000 mW calorimetric range.…”

Section: Flow Through Calorimeter Working In a ''Measuring Loop'' (Ml)mentioning

confidence: 99%

Control of continuous polyhydroxybutyrate synthesis using calorimetry and flow cytometry

Maskow

Müller

Lösche

et al. 2006

Biotech & Bioengineering

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The substrate-carbon flow can be controlled in continuous bioreactor cultures by the medium composition, for example, by the C/N ratio. The carbon distribution is optimal when a maximum fraction flows into the desired product and the residual is just sufficient to compensate for the dilution of the microbial catalyst. Undershooting of the latter condition is reflected immediately by changes in the Gibbs energy dissipation and cellular states. Two calorimetric measurement principles were applied to optimize the continuous synthesis of polyhydroxybutyrate (PHB) by Variovorax paradoxus DSM4065 during growth with constantly increasing supply rates of fructose or toxic phenol. Firstly, the changed slope of the heat production rate in a complete heat balanced bioreactor (CHB) indicated optimum carbon channeling into PHB. The extent of the alteration depended directly on the toxic properties of the substrate. Secondly, a flow through calorimeter was connected with the bioreactor as a "measurement loop." The optimum substrate carbon distribution was indicated by a sudden change in the heat production rate independent of substrate toxicity. The sudden change was explained mathematically and exploited for the long-term control of phenol conversion into PHB. LASER flow cytometry measurements distinguished between subpopulations with completely different PHB-content. Populations grown on fructose preserved a constant ratio of two subpopulations with double and quadruple sets of DNA. Cells grown on phenol comprised a third subpopulation with a single DNA set. Rising phenol concentrations caused this subpopulation to increase. It may thus be considered as an indicator of chemostress.

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“…The latter was placed after the measuring vessel and equipped with Viton tubing (0.9 cm diameter) of very low gas porosity. The pumping rate of the cell suspension through the flow calorimeter was 120 cm 3 /h and, owing to recent improvements in design (see Guan et al, 1999;O'Neill et al, 2003), the influence of changing this rate was found to be negligible over the range from 30 to 180 cm 3 /h. Using the base-catalyzed hydrolysis of methyl 4-hydroxybenzoate (methyl paraben) for the chemical calibration (O'Neill et al, 2003), the experimentally derived thermal volume was found to be 1.28 F 0.20 cm 3 , which differs significantly from the nominal (engineered) volume of 1 cm 3 (Guan et al, 1999).…”

Section: Cultivationmentioning

confidence: 99%

“…The pumping rate of the cell suspension through the flow calorimeter was 120 cm 3 /h and, owing to recent improvements in design (see Guan et al, 1999;O'Neill et al, 2003), the influence of changing this rate was found to be negligible over the range from 30 to 180 cm 3 /h. Using the base-catalyzed hydrolysis of methyl 4-hydroxybenzoate (methyl paraben) for the chemical calibration (O'Neill et al, 2003), the experimentally derived thermal volume was found to be 1.28 F 0.20 cm 3 , which differs significantly from the nominal (engineered) volume of 1 cm 3 (Guan et al, 1999). As discussed by O'Neill et al (2003), the difference is due to the heat produced by the reaction in the tubing leading to and exiting from the nominal ''vessel'' (see Guan et al, 1999), which contributes to the total measured heat flow rate.…”

Section: Cultivationmentioning

confidence: 99%

“…Using the base-catalyzed hydrolysis of methyl 4-hydroxybenzoate (methyl paraben) for the chemical calibration (O'Neill et al, 2003), the experimentally derived thermal volume was found to be 1.28 F 0.20 cm 3 , which differs significantly from the nominal (engineered) volume of 1 cm 3 (Guan et al, 1999). As discussed by O'Neill et al (2003), the difference is due to the heat produced by the reaction in the tubing leading to and exiting from the nominal ''vessel'' (see Guan et al, 1999), which contributes to the total measured heat flow rate. This correction is then applied to the data for the cells pumped in suspension through the system.…”

Section: Cultivationmentioning

confidence: 99%

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Flow calorimetry and dielectric spectroscopy to control the bacterial conversion of toxic substrates into polyhydroxyalcanoates

Maskow

Olomolaiye

Breuer

et al. 2004

Biotech & Bioengineering

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The microbial conversion of toxic substrates into valuable products in continuous culture requires the equivalent of a tight rope walk between formation of the desired product and intoxication of the microbial catalyst. The condition of the latter is reflected immediately by changes in heat flow rate and beta-dispersion in an electrical RF field. Therefore, these were applied to the example of the continuous growth-associated synthesis of polyhydroxyalcanoates (PHA) from phenol by the bacterial strain Variovorax paradoxus DSM 4065. By controlling the supply of phenol to the chemostat, the rates of degradation, biomass formation, and synthesis of target product, respectively, were increasingly elevated until the onset of poisoning the organisms. The boundary between the maximum rates and the initiation of intoxication coincided with a sudden change in the heat flux. Using this occurrence, it was possible to develop a control strategy and test it successfully for a time period of 80 h. After 40 h the process stabilized at mean values, i.e., at rates of 92% phenol degradation, 100% biomass formation, and 70 - 75% of PHA formation compared with the situation shortly before poisoning the organisms. Using a moving-average technique to filter the raw dielectric spectroscope data, changes were followed in biomass concentration of approximately 100 mg/L. However, this technique was not sensitive or rapid enough to control the process.

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The base catalysed hydrolysis of methyl paraben: a test reaction for flow microcalorimeters used for determination of both kinetic and thermodynamic parameters

Cited by 47 publications

References 10 publications

Chip Calorimetry for Fast and Reliable Evaluation of Bactericidal and Bacteriostatic Treatments of Biofilms

Chip Calorimetry for Fast and Reliable Evaluation of Bactericidal and Bacteriostatic Treatments of Biofilms

Control of continuous polyhydroxybutyrate synthesis using calorimetry and flow cytometry

Flow calorimetry and dielectric spectroscopy to control the bacterial conversion of toxic substrates into polyhydroxyalcanoates

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