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

Abstract

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.

Factors Affecting Reduction in Preservative Efficacy in Nonwoven Fabrics

“…Microbial growth on the nonwoven fabrics was measured using a multiplex batch calorimeter (ADVANCE RIKO, Inc., Yokohama, Japan) , as previously reported (Takahashi, 1996) . Microbial calorimetry is a method for monitoring microbial growth by determining the metabolic heat generated due to microbial growth and recording the evolution of heat in time under the form of a voltage signal (Antoce et al, 1996b;Okada et al, 1998) .…”

“…It is well known that disinfectants including benzalkonium chloride or chlorhexidine gluconate cannot exert sufficient bactericidal effects owing to their adsorption onto gauze or surgical cotton (Bloss et al, 2010;Kundsin and Walter, 1957;Yohkoh, 1986) . Conversely, microbial growth reportedly increases upon attachment to materials with a broad surface area (Okada et al, 1998;Kobayashi et al, 1991) . However, the mechanism underlying the reduction in the preservative efficacy in nonwoven fabrics remains unclear.…”