The application of a novel heat flux calorimeter for studying growth of Escherichia coli W in aerobic batch culture

Abstract

The modification and principle of a novel heat flux calorimeter for the in siru, on-line measurement of the heat generated during microbial growth is described. Data concerning the physical characterization of the calorimeter as a fermentor, including stability and sensitivity of the heat signal, are presented. The calorimeter has been successfully applied to the study of the aerobic batch culture of Escherichia coli W on glucose under carbon and nitrogen limitation. A direct correlation between growth and heat evolution was obtained. Quantitative analysis of the data suggests that the new calorimetric technique could be used for monitoring growth and specific metabolic events, for convenient medium optimization, and as a basis for a novel fermentation process control system.

The heat generated by yeast cultures with a mixed metabolism in the transition between respiration and fermentation

“…(11). It has been shown that expression (6) reduces to a constant of about 460 kJ/mole of 0, for strongly aerobic processes.I7 In an increasingly fermentative metabolism, Yi,s will fall and Y & will increase in such a way that the denominator, which in fact is an expression for Y&, will become zero and will drive the heat yield to infinity.…”

“…In these equations, y, and 6, are the degrees of reductance and hydrogenation, respectively, which are defined as fol- (11) i o~~: '~ y l = 4 + el, -2el, -3e,,…”

Development of Bioreaction Engineering

“…), the precursors of the secondary metabolites, NAD(P)H, RNA, DNA, proteins, and cell morphology [130,257]. The heat generated by the microorganisms [258][259][260][261][262][263] and the intracellular enzyme activities and metabolites [264][265][266][267][268][269] are monitored as well. In special cases, the intracellular enzyme activities were measured on-line [270][271][272][273][274].…”

The use of calorimetry in biotechnology

“…As early as 1968, Cooney et al 24) pioneered the completely novel development of calorimeters at the bench scale. Three different types of bench scale calorimeters for use in biotechnology have been described in the literature to date [24][25][26][27][28][29][30][31]. They all consist of a laboratory bioreactor with a nominal volume comprising between 2 and 14 1, which can be operated much like a standard laboratory reactor, while featuring the necessary equipment for measuring the heat generated by the microbial culture in situ.…”

“…It is obvious that this new form of calorimetry, which has become known in chemical engineering literature as 'Isothermal Reaction Calorimetry' 32) is especially well suited for quantitative investigations of microbially generated heat-fluxes under technically realistic processing conditions. Their main disadvantage, a relatively low sensitivity, can, in part, be overcome by using a novel "heat-flux" measuring principle 30) Judging from published results, the more recent experimental techniques developed in the last decade will probably expand the usefulness of calorimetry in biotechnology from the traditional field of utilization of microcalorimetry to incorporate more quantitative process-engineering related applications, some of which are summarized in Table 2.…”