Productivity and heat generation of fermentation under oxygen limitation

Abstract

The elemental balance equation of microbial growth on carbon substrate of generalized composition is given. Yield of dried bio-mass per oxygenY _o is calculated. Yield per oxygenY _o is found to be determined by two factors—carbon yieldy and the reducing power of substrate γ _s . The mode of dependence ofY _o on these two quantities is studied. The energetic interpretation ofy and γ _s is given. The dependence ofY _o ony and γ _s is shown to be equivalent to the dependence on a single factor, the energetie yield of growth η. Fermentor productivity increases with growth of η, the increase being directly proportional if η is not large (up to 25%) and becoming steeper if η is larger. The restrictions on a range of workable carbon yields during growth on various substrates are found. Metabolic heat generation of fermentor is shown to be proportional to oxygen consumption and to average 3.38 kcal per gram of O₂ irrespective of substrate and microorganism used.