Microcalorimetric studies of chemostat cultures of Klebsiella aerogenes

The heat output of steady-state cells of Klebsiella aerogenes growing in Carbon limited and Carbon-sufficient media was measured with an LKB flow-microcalorimeter. Problems associated with oxygen shortage were eliminated by using low substrate concentrations, higher aeration rates,and high pump rate...

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Main Author: Djavan, Ali
Published: Royal Holloway, University of London 1980
Subjects:
579
Online Access:http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255450
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spelling ndltd-bl.uk-oai-ethos.bl.uk-2554502017-03-16T16:16:13ZMicrocalorimetric studies of chemostat cultures of Klebsiella aerogenesDjavan, Ali1980The heat output of steady-state cells of Klebsiella aerogenes growing in Carbon limited and Carbon-sufficient media was measured with an LKB flow-microcalorimeter. Problems associated with oxygen shortage were eliminated by using low substrate concentrations, higher aeration rates,and high pump rates through the microcalorimeter. The recorded heat output was extrapolated to the heat production by cells in the chemostat, and this was converted to specific heat output, DeltaH<sub> p</sub>/kJ (g cell)<sup>-1</sup>. i.e. the heat output of formation of 1 g cell during one generation time. This enabled direct comparison of the heat production for different dilution rates and growth under different conditions. In C-limited cultures both DeltaH<sub>p</sub> and molar growth yield increased with increasing dilution rate and attained constant values at D > 0.5 h<sup> -1</sup> . In C-limited media DeltaH<sub>p</sub> was the same irrespective of substrate concentration and carbon source. Although the specific heat output was much greater in C-sufficient than in C-limited chemostats, it was independent of the concentration of limiting nutrient and glucose, provided glucose was supplied in excess. The increased heat output produced by adding small amounts of different substrates to glucose-limited chemostats depended on the added C-source; four types of substrate were recognised. The additional heat output increased linearly with the amount of added acetate, but not with glucose and pyruvate. Small amounts of uncouplers disturbed the steady-state heat output and the increased heat output was related to the stimulation of the ATPase system. The enhanced heat output when the pH was increased to 8, was associated with proton translocating ATPase activity. The maintenance energy obtained from the variation of the growth yield and specific heat output with dilution rate for glucose- and glycerol-limited chemostats, was partly growth rate-dependent, m<sub>g</sub>, and partly growth rate-independent, m<sup>'</sup><sub>s</sub> These values were related to the maintenance coefficients reported in the literature.579BiochemistryRoyal Holloway, University of Londonhttp://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255450http://repository.royalholloway.ac.uk/items/0a33bad4-ddc6-4d5a-b9f5-64faef17f8cb/1/Electronic Thesis or Dissertation
collection NDLTD
sources NDLTD
topic 579
Biochemistry
spellingShingle 579
Biochemistry
Djavan, Ali
Microcalorimetric studies of chemostat cultures of Klebsiella aerogenes
description The heat output of steady-state cells of Klebsiella aerogenes growing in Carbon limited and Carbon-sufficient media was measured with an LKB flow-microcalorimeter. Problems associated with oxygen shortage were eliminated by using low substrate concentrations, higher aeration rates,and high pump rates through the microcalorimeter. The recorded heat output was extrapolated to the heat production by cells in the chemostat, and this was converted to specific heat output, DeltaH<sub> p</sub>/kJ (g cell)<sup>-1</sup>. i.e. the heat output of formation of 1 g cell during one generation time. This enabled direct comparison of the heat production for different dilution rates and growth under different conditions. In C-limited cultures both DeltaH<sub>p</sub> and molar growth yield increased with increasing dilution rate and attained constant values at D > 0.5 h<sup> -1</sup> . In C-limited media DeltaH<sub>p</sub> was the same irrespective of substrate concentration and carbon source. Although the specific heat output was much greater in C-sufficient than in C-limited chemostats, it was independent of the concentration of limiting nutrient and glucose, provided glucose was supplied in excess. The increased heat output produced by adding small amounts of different substrates to glucose-limited chemostats depended on the added C-source; four types of substrate were recognised. The additional heat output increased linearly with the amount of added acetate, but not with glucose and pyruvate. Small amounts of uncouplers disturbed the steady-state heat output and the increased heat output was related to the stimulation of the ATPase system. The enhanced heat output when the pH was increased to 8, was associated with proton translocating ATPase activity. The maintenance energy obtained from the variation of the growth yield and specific heat output with dilution rate for glucose- and glycerol-limited chemostats, was partly growth rate-dependent, m<sub>g</sub>, and partly growth rate-independent, m<sup>'</sup><sub>s</sub> These values were related to the maintenance coefficients reported in the literature.
author Djavan, Ali
author_facet Djavan, Ali
author_sort Djavan, Ali
title Microcalorimetric studies of chemostat cultures of Klebsiella aerogenes
title_short Microcalorimetric studies of chemostat cultures of Klebsiella aerogenes
title_full Microcalorimetric studies of chemostat cultures of Klebsiella aerogenes
title_fullStr Microcalorimetric studies of chemostat cultures of Klebsiella aerogenes
title_full_unstemmed Microcalorimetric studies of chemostat cultures of Klebsiella aerogenes
title_sort microcalorimetric studies of chemostat cultures of klebsiella aerogenes
publisher Royal Holloway, University of London
publishDate 1980
url http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255450
work_keys_str_mv AT djavanali microcalorimetricstudiesofchemostatculturesofklebsiellaaerogenes
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