Endothermic microbial growth. A calorimetric investigation of an extreme case of entropy-driven microbial growth

Life is almost always associated with the generation of heat. Thus far, all chemotrophic life forms that have been studied in calorimeters were found to be exothermic. Certain literature reports have even cast doubt on the existence of endothermic growth, even though thermodynamic principles do not rule it out. The present report describes the first experiments demonstrating the actual existence of chemotrophic life forms that take up heat rather than produce i

Large-scale calorimetry and biotechnology

A review with 75 refs. of calorimetric techniques used and results obtained in calorimetric expts. aimed at developing quant. relation between heat release and other important process parameters for potential use in monitoring and controlling tech. bioprocesses. [on SciFinder (R)

A novel bench-scale calorimeter for biological process development work

A modified heat-flux, computer-assisted bench calorimeter is described for continuous in situ measurement of heat generated during the growth of microorganisms in submerged cultures under std. lab. conditions of temp., aeration, agitation, and pH. The calorimeter does not rely on heat balance and makes insulation of the app. unnecessary. The modified calorimeter is sensitive enough to permit accurate and easy monitoring of the heat dissipated by a weakly exothermic culture of Escherichia coli under stirred and aerobic conditions. [on SciFinder (R)

Ceramic hydroxyapatite: a new tool for separation and analysis of IgA monoclonal antibodies

A novel downstream process is reported for preparative scale prodn. of dimeric IgA, a protein with potential pharmaceutical applications. Time-consuming size exclusion chromatog. was replaced by ceramic hydroxyapatite chromatog. (CHT). A clear baseline sepn. of the dimeric IgA from the polymeric forms using a step-gradient-step protein elution program is described. Application of this method for IgA anal. during prodn. is suggested. [on SciFinder (R)

Calorimetry of technical microbial reactions

Heat generation is a very conspicuous phenomenon in large scale bioreactors and could in principle quite easily be measured by the temp. increase of the cooling water. Taking yeast cultures growing on a mixed oxido-reductive metab. for various reasons as an example, this paper demonstrates how heat dissipation measurements may be used in combination with other convenient online measurements order to obtain a quant. estn. of the nature of the on-going metab. and of the current overall stoichiometry. The application of such measurements to controlling fed-batch cultures is also discussed. [on SciFinder (R)

Calorimetry and energetic efficiencies in aerobic and anaerobic microbial growth

A simple definition of the energetic growth efficiency both in terms of enthalpy and free energy is given and discussed. In cultures growing by respiratory catabolism, these efficiencies may conveniently be obsd. online by isothermal reaction calorimetry. If the fermentative part of catabolism is important, the free energy growth efficiency must be evaluated based on biomass yield measurements. In continuous cultures of 2 yeasts growing by respiration, by pure fermn., and on a mixed catabolism, the efficiency was always 0.5-0.6 despite widely varying growth yields. [on SciFinder (R)