title: Hydrogen production by the hyperthermophilic bacteriumThermotoga maritimaPart II: modeling and experimental approaches for hydrogen production.
abstract: BACKGROUND
  Thermotoga maritimais a hyperthermophilic bacterium known to produce hydrogen from a large variety of substrates. The aim of the present study is to propose a mathematical model incorporating kinetics of growth, consumption of substrates, product formations, and inhibition by hydrogen in order to predict hydrogen production depending on defined culture conditions.
  
  
  RESULTS
  Our mathematical model, incorporating data concerning growth, substrates, and products, was developed to predict hydrogen production from batch fermentations of the hyperthermophilic bacterium,T. maritima. It includes the inhibition by hydrogen and the liquid-to-gas mass transfer of H2, CO2, and H2S. Most kinetic parameters of the model were obtained from batch experiments without any fitting. The mathematical model is adequate for glucose, yeast extract, and thiosulfate concentrations ranging from 2.5 to 20 mmol/L, 0.2-0.5 g/L, or 0.01-0.06 mmol/L, respectively, corresponding to one of these compounds being the growth-limiting factor ofT. maritima. When glucose, yeast extract, and thiosulfate concentrations are all higher than these ranges, the model overestimates all the variables. In the window of the model validity, predictions of the model show that the combination of both variables (increase in limiting factor concentration and in inlet gas stream) leads up to a twofold increase of the maximum H2-specific productivity with the lowest inhibition.
  
  
  CONCLUSIONS
  A mathematical model predicting H2production inT. maritimawas successfully designed and confirmed in this study. However, it shows the limit of validity of such mathematical models. Their limit of applicability must take into account the range of validity in which the parameters were established.
authors.affiliation: Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, Mediterranean Institute of Oceanography, 13288 Marseille, France.
authors.forename: Richard
authors.identifier: 0000-0002-9268-6948
authors.initials: R
authors.lastname: Auria
authors.affiliation: Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, Mediterranean Institute of Oceanography, 13288 Marseille, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Boileau
authors.affiliation: Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, Mediterranean Institute of Oceanography, 13288 Marseille, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Davidson
authors.affiliation: Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, Mediterranean Institute of Oceanography, 13288 Marseille, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Casalot
authors.affiliation: Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, Mediterranean Institute of Oceanography, 13288 Marseille, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Christen
authors.affiliation: Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, Mediterranean Institute of Oceanography, 13288 Marseille, France.
authors.forename: Pierre Pol
authors.initials: PP
authors.lastname: Liebgott
authors.affiliation: Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, Mediterranean Institute of Oceanography, 13288 Marseille, France.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Combet-Blanc
keywords: Hydrogen; Hyperthermophile; Inhibition; Modeling; Thermotoga maritima