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When glucose was added to a washed suspension of yeast under aerobic conditions, the heat production curve showed three distinct phases which reflect the metabolic process. The first phase showed a sharp peak which may be attributed to the uptake of glucose the rate of which was proportional to the cell concentration. The results of chemical analyses suggest that the second phase is connected to the metabolism of ethanol, which is followed by the third phase of endogenous metabolism. The second and third phases were nearly absent under anaerobic conditions or when respiration was inhibited. The amount of cellular trehalose, which serves as an energy source, was reflected by the physiological state of the cells, but showed little effect on heat production. The heat produced was proportional to the glucose concentration, depending on the temperature. There were some differences between glucose metabolism and endogenous metabolism in the temperature effect on the rate of heat production. Some correlations between heat production and ATP were observed under anaerobic conditions, but no correlation was observed under aerobic conditions. A comparison was made of enthalpy change with different types of metabolism of yeast. The calorimetric measurements are considered to be a useful approach in studying sugar uptake processes.

A rotatory calorimeter of the conduction type was remodelled to fit the continuous study of microbiological processes. Provisions for aeration and agitation made it possible to be used for calorimetric studies of microorganisms aerobically growing in a 5-ml culture. The time constant of the calorimeter response was found to be 8min and the calorimeter could be used for most kinetic studies on microbial cultures.By using a separate culture apparatus, quantitative analyses can be made on samples taken from parallel culture and the results can be correlated with the thermogram obtained with the calorimeter. The performance of the instrument was demonstrated with the aerobic growth of Saccharomyces cerevisiae. Calorimetric study by the use of the present model may give a detailed information at the cellular level about microbial growth processes when combined with turbidity measurements.

Differential scanning calorimetry (DSC) of double stranded DNA was carried out using plasmid pJL3-TB5 DNA (5277 base pairs), whose entire nucleotide sequence has been determined. The DSC curve for the linear DNA of the plasmid used in the present study gave seven separate peaks including two main peaks which range from 82° to 98°, suggesting that DNA melts independently at several cooperative blocks along the chain. The DSC curve obtained agreed with the histogram of the frequency versus GC content which was constructed from the GC distribution map along the DNA chain of pJL3-TB5. These results are obvious evidence that the thermal transition of DNA occurs blockwise along the molecular chain. The two main peaks were estimated to be due to the heat transition of the two distinct regions, containing 46-50% and 54-58% GC, respectively. DSC of covalently closed circular (ccc-) DNA of the same plasmid did not show any heat transition peak, indicating that ccc-form is stabilized compared with linear form.

Etude, en aerobiose ou en anaerobiose, de la production de chaleur par des spores d'Aspergillus oryzae ou de Bacillus cereus inoculees a du lait en poudre a teneur en eau prealablement equilibree. Parallelement on mesure, en anaerobiose, le taux d'O2 absorbe. Cette technique permet d'evaluer la correlation entre activite metabolique microbienne en dehors de toute multiplication cellulaire, et la teneur en eau du milieu

A considerable amount of heat was produced when a suspension of yeast was added to a suspending medium in the absence of an exogenous energy source. The amount of heat produced was proportional to the cell concentration and accompanied by oxygen consumption, suggesting that the exothermic reaction may be due to the endogenous metabolism of cells. The patterns of heat production varied with the physiological state of cells, which were influenced by several factors including culture conditions, methods of storage, starvation, temperature and the suspending medium used for calorimetric measurements.

The purpose of the present study is to investigate the relationship between the heat effects and the transport processes of glucose in S. cerevisiae by calorimetry and to gain the insight into the energy coupling between the transport and metabolic processes

By using a series of dry yeasts prepared to have various water contents, the resistivity to heat inactivation and cold medium treatment was studied.The heat resistance of the samples showed a marked dependence upon the water content, giving activation energies of 80kcal with relatively wet cells and 60kcal with relatively dried cells, respectively. The lowering of the biological activity shown after the rehydration with a cold medium was found to be prevented, at least partially, by preheating the sample at specified temperature before the rehydration procedure. This protective effect disappeared after several hour standing at room temperature, suggesting that the related physical state relaxed with a time constant of hours in order of magnitude.A domain map is presented to show diagrammatically the relationship between biological properties of the dry yeast and its related physical states in terms of the cell temperature and the cell water content.

(1)It was experimentally shown that the pattern of angular distribution of light scattered by moderately large microbial cells is roughly presented by the FRAUNHOFER diffraction theory for a circular slit. (2) When a parallel beam is used as the incident rays, cuvettes of usual size give, however, smoothed scattering pattern due to the finite effective volume of scattering centre. The light was shown still to be strongly scattered as theoretically expected into the forward direction. (3) Practically all the scattered light could therefore, be collected by using a light receiver with a large aperture placed close to a thin cuvette. providing thus a convenient method of obtaining the true absorption spectra of cell suspensions.(4) In accordance with RAYLEIGH-GANS' first approximation to the cross section of microbial cells of moderate size, the total extinction is given by the sum of scattering and absorption attenuation. A true scattering spectra, therefore, could be obtained as the difference of the extinction spectra observed with a usual narrow beam spectrophotometer and the true absorption spectra obtained by use of a wide angle apparatus such as the one mentioned above.(5) Even in the case of fairly high-populated suspension of Chlorella, the observed apparent absorption spectra are mostly due to scattering loss. The local feature of the curves reflects the mode of anomalous dispersion of the real part of refractive indices of cells.(6) A slow rise experienced in the spectrum of yeast at 450mμ is also mainly due to scattering interference and partly to the existence of anomalous dispersion of refractive indices. In the single scattering region, the absorption of cell contributes to the attenuation only through modifying the real part of refractive index and not directly through its imaginary part.

1) Yeast cells suspended in a solution of cetyltrimethylammonium bromide (CTAB), a typical cationic detergent, rapidly bind CTAB cations. The binding process is nearly completed in less than 2min, while the germicidal action continues for at least 1hr.2) The shape of overall binding curve shown by yeast cells is similar to that of multilayer adsorption isotherm.3) The mortality of CTAB-treated cells depends upon the weight ratio of bound CTAB to yeast cells. Calculations show that 10 times the cell surface area must be covered by the bound CTAB to produce 100% killing of the samples.

The dependence of the turbidity in yeast suspensions treated with various amounts of cetyltrimethylammonium bromide (CTAB) on the percentage of killed cells provides a means for the determination of the germicidal effect. Empirical equations which describe the observed relationship between turbidity and mortality were derived, and turbidity measurements necessary to estimate the killed fractions of the sample were described. The time course of the germicidal action of CTAB upon yeast cells was observed by using this method. The turbidity change thereby observed can be accounted for by the change in cell volume resulting from the cell degeneration. Some observations on different microbes treated with various germicides suggest that the present method may be applicable to other kinds of germicides and microbes.