Growth Thermograms Research Articles

Effects of Compressed Hydrocarbon Gases on the Growth Activity of Saccharomyces cerevisiae

The inhibitory action of compressed hydrocarbon gases on the growth of the yeast Saccharomyces cerevisiae was investigated quantitatively by microcalorimetry. Both the 50% inhibitory pressure (IP(50)) and the minimum inhibitory pressure (MIP), which are regarded as indices of the toxicity of hydrocarbon gases, were determined from growth thermograms. Based on these values, the inhibitory potency of the hydrocarbon gases increased in the order methane << ethane < propane < i-butane < n-butane. The toxicity of these hydrocarbon gases correlated to their hydrophobicity, suggesting that hydrocarbon gases interact with some hydrophobic regions of the cell membrane. In support of this, we found that UV absorbing materials at 260 nm were released from yeast cells exposed to compressed hydrocarbon gases. Additionally, scanning electron microscopy indicated that morphological changes occurred in these cells.

Effects of compression with ethane, ethylene and their fluorinated derivatives on yeast growth

The inhibitory effect of compressed gaseous C2 compounds on yeast growth was investigated quantitatively by microcalorimetry. The growth thermograms (heat output vs. incubation time) showed that all C2 compounds tested inhibited yeast growth. After quantification of yeast growth at various pressures, we determined the 50% inhibitory pressure (IP50) and the minimum inhibitory pressure (MIP) as indices which represent the inhibitory potency of gases. The lower the IP50 and MIP values, the greater the growth inhibitory effects of the gases. Based on these values, the inhibitory potency of the gases increased in the order: ethane (C2H6) < ethylene (C2H4) < pentafluoroethane (C2HF5) < 1,1,1,2-tetrafluoroethane (C2H2F4). Furthermore, transmission electron microscopy (TEM) of yeast cells treated with compressed ethylene showed that the inner structures of the cells, especially the nuclear membrane and cytoplasmic membrane, were damaged.

Effects of compressed unsaturated hydrocarbon gases on yeast growth

The effect of compressed unsaturated hydrocarbon gases on the growth of the yeast Saccharomyces cerevisiae was investigated by microcalorimetry. The growth thermograms showed that unsaturated hydrocarbon gases inhibited yeast growth. As an approach to determining the comparative toxicity of unsaturated hydrocarbon gases, we determined the 50% inhibitory pressure (IP(50)) and the minimum inhibitory pressure (MIP). On the basis of the IP(50) and MIP values, the inhibitory potency of the gases increased in the order ethylene < propylene < 1-butene. Additionally, scanning electron microscopy showed that cells treated with unsaturated hydrocarbon gases were damaged, including invagination of the cell surface.

Effect of High-Pressure Gas on Yeast Growth

Microcalorimetry is a useful tool for monitoring the growth behavior of microorganisms. In this study, microcalorimetry was used to investigate the effects of nitrogen, air, oxygen, nitrous oxide, argon, and krypton at high pressure on the growth of the yeast Saccharomyces cerevisiae. Growth thermograms (metabolic heat vs. incubation time) were generated to estimate metabolic activity under compressed gases and to determine the 50% inhibitory pressure (IP(50)) and minimum inhibitory pressure (MIP), which are regarded as indices of the toxicity of compressed gases. Based on MIP values, the most toxic to the least toxic gases were found to be: O(2) > N(2)O > air > Kr > N(2) > Ar.

Evaluation of growth activity of microbes in tea field soil using microbial calorimetry

Calorimetry was used to study the heat evolution associated with microbial growth in tea field soils (growth thermograms) during the microbial degradation of added organic matter. From the actual heat evolution curves (f(t) curves) derived from the growth thermograms under various conditions of pH and water content of the tea field soils, the apparent growth rate constant (μ′) of soil microbes was determined as an index of their growth activity. In addition, μ′ was compared between tea field soils treated with organic versus compound fertilizer. From the results, the following conclusions were made: (i) In acidic tea field soil (pH less than about 6.0), the growth activity of soil microbes declined with decreasing pH, and μ′ was twofold higher at pH 6.0 than at pH 4.3. (ii) In tea field soils (Andosol) with a water content less than about 50%maximum water holding capacity (MWHC), the growth activity declined with decreasing water content, and μ′ at 52.5%MWHC was double that at 35.2%MWHC. (iii) The growth activity of microbes in tea field soil treated with organic fertilizer was approximately 1.2-fold higher than that treated with compound fertilizer.

Evaluation of Growth Activity of Microbes in Tea Field Soil Using Microbial Calorimetry

Calorimetry was used to study the heat evolution associated with microbial growth in tea field soils (growth thermograms) during the microbial degradation of added organic matter. From the actual heat evolution curves (f(t) curves) derived from the growth thermograms under various conditions of pH and water content of the tea field soils, the apparent growth rate constant (μ′) of soil microbes was determined as an index of their growth activity. In addition, μ′ was compared between tea field soils treated with organic versus compound fertilizer. From the results, the following conclusions were made: (i) In acidic tea field soil (pH less than about 6.0), the growth activity of soil microbes declined with decreasing pH, and μ′ was twofold higher at pH 6.0 than at pH 4.3. (ii) In tea field soils (Andosol) with a water content less than about 50%maximum water holding capacity (MWHC), the growth activity declined with decreasing water content, and μ′ at 52.5%MWHC was double that at 35.2%MWHC. (iii) The growth activity of microbes in tea field soil treated with organic fertilizer was approximately 1.2-fold higher than that treated with compound fertilizer.

1N1330 酵母の増殖サーモグラムに対する高圧ガスの影響(12.細胞生物学的課題,一般演題,日本生物物理学会第40回年会)

1N1330 酵母の増殖サーモグラムに対する高圧ガスの影響(12.細胞生物学的課題,一般演題,日本生物物理学会第40回年会)

Calorimetric study on the effect of 60Co γ-rays on the growth of microorganisms

Using a calorimeter equipped with 24 sample units, the heat evolution from growing Saccharomyces cerevisiae, Escherichia coli and spores of Bacillus pumilus and Bacillus stearothermophilus was detected in the form of growth thermograms. Irradiation with 60Co γ-rays affected the growth pattern, which was used for a quantitative analysis of the effect on microorganisms. Irradiation of B. pumilus and B. stearothermophilus spores led to dose-dependent delays in growth, indicating a bactericidal effect. In case of 60Co γ-irradiated S. cerevisiae, a dose-dependent reduction of the growth rate constant was observed together with the retardation in growth, indicating a combination of bactericidal and bacteriostatic effects. An equation to determine the number of survivors on the basis of the retardation in growth t α and the growth rate constant μ was developed, which proved the opportunity to use the calorimetric technique in predictive microbiology.

Bacteriostatic and Bactericidal Actions of Antimicrobial Drugs Studied by Microbial Calorimetry.

Antimicrobial actions of p-hydroxybenzoate alkyl esters (parabens) and two formalin derivatives, Quarternium 15 (Q15) and imidazolidinyl urea (IDU), which are commonly used in cosmetics and toiletries as preservatives or bactericides, were evaluated against Klebsiella pneumoniae using a technique of microbial calorimetry. With parabens, which are known to have bacteriostatic actions, increased concentrations caused changes in the growth thermograms of the microorganism characterized by a suppression in the slopes at the exponential growth phase. In contrast, with Q15 and IDU, which are known to have rather strong bactericidal effects the growth thermograms shifted toward a longer incubation time in proportion to the drug concentration while their shapes were unchanged. These two types of actions were compared in terms of two indexes: the changes in the growth rate constant and in the apparent growth retardation. In the case of bacteriostatic drugs such as parabens, antimicrobial actions resulted in the growth retardation due to the lowering of the growth rate constant. In contrast, bactericidal drugs such as formalin preservatives did not affect the growth rate constant and caused only an apparent retardation in growth. The observed difference in the change of growth thermogram patterns is discussed in terms of a difference in the two drug potency curves drawn on the basis of the two indexes.

Microbial Calorimetry of Supported Cultures and Its Application to the Study of Antimicrobial Action.

Microbial calorimetry was applied to urethane foam-supported cultures of Klebsiella pneumoniae and Aspergillus oryzae to quantitatively evaluate the growth activity of microbes. The amplitude of calorimetric signals observed for the growth of microbes in a medium with porous urethane foam support was found to be markedly greater than that in stationary cultures in ordinary liquid media. For quantitative comparison, the maximal amplitude of the calorimetric signal, the growth rate constant and the doubling time were evaluated from the growth thermograms observed. The result obtained was that the growth activity of K. pneumoniae cultured on urethane foam increased about 10-fold that of cultures in liquid medium, as judged by the thermopile output signal at the peak time and about 1.7-fold in terms of the growth rate constant. The values observed for the supported culture of A. oryzae were about 1.5-fold and about 3-fold higher, respectively. The method was also applied to study the effect of sodium benzoate on the urethane foam-supported culture of A. oryzae, and its inhibitory action was quantitatively discussed.

Inhibitory Effect of Decanoic Acid on Yeast Growth at Various pHs and Ethanol Concentrations.

A multiplex batch calorimeter was used to monitor the heat evolution during incubation of yeast cultures in the presence of decanoic acid at various concentrations. The changes observed in the recorded growth thermograms when the concentration of decanoic acid increased were quantitatively described using the values of the growth rate constantμ determined for each culture from the calorimetric recording. This made possible the calculation of the 50% inhibitory concentration (K μ) and the 100% inhibitory concentration (MIC μ) of decanoic acid in relation to the growth of four yeast strains at 30°C. By using adequate control cultures, it was possible to distinguish the separate inhibitory effect of decanoic acid and ethanol, as well as their combined effect. Other experiments with a strain of Saccharomyces cerevisiae showed that the “apparent” Kμ and MIC μ values (calculated on the basis of the total decanoic acid added to the cultures) increased with the pH, while the corresponding K μ and MIC μ values calculated on the basis of the amount of undissociated decanoic acid remained relatively constant, indicating that the toxic action is due mainly to the undissociated form of the acid. The “apparent” K μ and MIC μ values of decanoic acid at pH 5.5 also depended on the ethanol concentration in the medium, showing a marked decrease when the initial ethanol concentration varied from 0.33% to about 1.0% (v/v), and then decreasing only slightly when the concentration of ethanol increased to 6.25% (v/v).

A Calorimetric Method Applied to the Study of Yeast Growth Inhibition by Alcohols and Organic Acids

Using a conduction-type isothermal batch calorimeter with 24 units, the heat evolved during growth of four yeast strains from different species in the presence of various concentrations of normal alcohols (C1-C4) and saturated organic acids (C2, C4, C6, C8, C10) was recorded as growth thermograms. Changes in the growth thermograms were observed when the inhibitor concentration increased, and they were correlated to the determined values of the growth rate constant. Subsequent analysis allowed precise determination of the 50% inhibitory concentration (<i>K</i>_i) and the 100% inhibitory concentration (MIC) for the growth of the yeast strains in the presence of the studied alcohols and acids. The combined inhibitory action of ethanol and some acids was also investigated, and it was found that ethanol presence leads to a decrease in the <i>K</i>_i and MIC values of the acids, suggesting an additive or synergistic activity mechanism. The advantages of the method, as well as influencing factors are also discussed.

Quantitative study of yeast growth in the presence of added ethanol and methanol using a calorimetric approach.

Using a calorimeter with 24 sample units the heat evolved during incubation of yeast cultures at 30 degrees C was detected in the form of growth thermograms. Ethanol and methanol added to the culture medium produced changes in the growth thermograms that could be analyzed to calculate the 50% inhibitory concentration (Ki) and minimum inhibitory concentration (MIC). Correlation of the heat evolution curves with the number of cells and the turbidity of the culture was found to be very good. It was found that addition of ethanol and methanol up to 7.65% had clear effects of inhibition on growth of all yeast strains studied, reducing the growth rate constant and delaying growth. However, the amounts of ethanol produced from the nutrients available in the culture vial was only little affected by the initial addition of up to 7.65% (v/v) of ethanol or methanol in the medium.

A study of the optimum fungistatic action of a synthetic medicine using a microcalorimetric method

In this paper, we have determined bacterial growth thermograms using a thermal activity monitor. We have also determined bacterial growth thermograms of inhibitor and have studied the fungistatic action of a synthetic medicine (W2). We have calculated the rate constant at different concentrations and with the optimum allowable concentration of the synthetic medicine W2.

Determination of thermograms of bacterial growth and study of optimum growth temperature

In this paper, we have determined bacterial growth thermograms by using the 2277 thermal activity monitor. We have studied the multiplication curve of bacteria at different temperatures and calculated the rate constant and optimum growth temperature.

Measurement of multiplication rate of Bacillus sp. NTT-61 growth and study on its thermodynamic properties

The fundamental growth thermograms of Bacillus sp. NTT-61 have been determined by the microcalorimetric method. From these thermograms we calculate the multiplication rate constant K a and activation energy E a A formula for bacterial growth is given as ▪ where X is the bacterium, S the substrate, (X·S) the bacterium-substrate complex, P the product, and K a the rate constant. This pattern is similar to the transition state pattern in chemistry, so according to the transition state theory of reaction dynamics we can calculate the activation entropy (Δ S ≠) and activation free enthalpy (Δ G ne) of bacterial growth processes. These are very useful data with which to study bacterial thermodynamic properties.

Calorimetric Analysis of the Effects of Penicillin G, Ampicillin and Polymyxin B on the Growth ofEscherichia coli

Calorimetri analysis was performed of the effects of penicillin G, ampicillin and polymyxin B on Escherichia coli grown on bouillon medium at pH 6.2 and 37°C. The presence of any one of these drugs shifted the patterns of growth thermograms toward longer incubation periods, although the growth rate constant remained almost unchanged. The changes in the thermogram patterns were analyzed by means of a simple mathematical model and parameters needed to characterize the actions of the drugs on the growth of E. coli were determined. The drug concentrations at which the number of viable cells at the start of incubation decreased by half during the incubation were 6.94, 0.46 and 0.04 μmol dm−3 for penicillin G, ampicillin and polymyxin B, respectively. Drug potency curves were drawn for the three drugs using the parameters determined.

Microcalorimetric study of bacterial growth

The fundamental growth thermograms of Escherichia coli, Staphylococcus aureus, Salmonella typhosa, Salmonella chaleraeuis and Shigella flexneri have been determined by the microcalorimetric method. These perfect thermogram curves reflect the changes of bacterial growth patterns (including the lag phase of growth, log growth, stationary phase and decline phase of growth). In our experiments, highly characteristic and reproducible growth patterns are observed under the same conditions; therefore, one can use these thermograms as a “finger print” to identify bacteria. Further research on these thermograms has enabled us to calculate the multiplication rate constant and activation energy of bacterial growth. Obviously, these thermogram curves contain ample information which is very significant for studies in microbiological, bio-ther- mokinetic and clinical fields.

Calorimetric analysis of the effects of penicillin G, ampicillin and polymyxin B on the growth of Escherichia coli.

Calorimetric analysis was performed of the effects of penicillin G, ampicillin and polymyxin B on Escherichia coli grown on bouillon medium at pH 6.2 and 37°C. The presence of any one of these drugs shifted the patterns of growth thermograms toward longer incubation periods, although the growth rate constant remained almost unchanged. The changes in the thermogram patterns were analyzed by means of a simple mathematical model and parameters needed to characterize the actions of the drugs on the growth of E. coli were determined. The drug concentrations at which the number of viable cells at the start of incubation decreased by half during the incubation were 6.94, 0.46 and 0.04μmoldm-3 for penicillin G, ampicillin and polymyxin B, respectively. Drug potency curves were drawn for the three drugs using the parameters determined.

Calorimetrie Analysis of the Effect of Streptomycin, Tetracycline and Chloramphenicol on the Growth ofEscherichia coli

The effects of streptomycin, tetracycline and chloramphenicol on the growth of Escherichia coli were studied quantitatively in a conduction-type batch calorimeter at pH 6.2 and 37°C. Change in the growth thermograms with increasing drug concentrations in the medium were analyzed with a kinetic model of non-competitive inhibition. The number of drug molecules needed to inactivate a unit viable cell, m, was estimated to be 1.2 + 0.1, 0.7 ±0.1 and 1.3 ±0.1 for streptomycin, tetracycline and chloramphenicol, respectively. With the assumption that the drug binding sites are all identical, the microscopic dissociation constant per binding site, K, for the drugs was found to be 0.19, 0.43 and 0.94μmoldm-3 for streptomycin, tetracycline and chloramphenicol, respectively. With these m and K{ values, drug potency curves were drawn for the three drugs.