Continuous cultures limited by a gaseous substrate: Development of a simple, unstructured mathematical model and experimental verification with Methanobacterium thermoautotrophicum

N Schill, W. M. Van Gulik, D Voisard, U von Stockar

    Research output: Contribution to journalArticleScientificpeer-review

    54 Citations (Scopus)

    Abstract

    This article presents a simple, unstructured mathematical model describing microbial growth in continuous culture limited by a gaseous substrate. The model predicts constant gas conversion rates and a decreasing biomass concentration with increasing dilution rate. It has been found that the parameters influencing growth are primarily the gas transfer rate and the dilution rate. Furthermore, it is shown that, for correct simulation of growth, the influence of gaseous substrate consumption on the effective gas flow through the system has to be taken into account. Continuous cultures of Methanobacterium thermoautotrophicum were performed at three different gassing rates. In addition to the measurement of the rates of biomass production, product formation, and substrate consumption, microbial heat dissipation was assessed using a reaction calorimeter. For the on-line measurement of the concentration of the growth-limiting substrate, H2, a specially developed probe has been used. Experimental data from continuous cultures were in good agreement with the model simulations. An increase in gassing rate enhanced gaseous substrate consumption and methane production rates. However, the biomass yield as well as the specific conversion rates remained constant, irrespective of the gassing rate. It was found that growth performance in continuous culture limited by a gaseous substrate is substantially different from 'classic' continuous culture in which the limiting substrate is provided by the liquid feed. In this report, the differences between both continuous culture systems are discussed.

    Original languageEnglish
    Pages (from-to)645-658
    Number of pages14
    JournalBiotechnology and Bioengineering
    Volume51
    Issue number6
    DOIs
    Publication statusPublished - 20 Sep 1996

    Keywords

    • amperometric measurement of dissolved H concentration
    • continuous culture
    • gaseous substrate limitation
    • mathematical modeling
    • Methanobacterium thermoautotrophicum
    • reaction calorimetry

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