Process Biotechnology
  

Microbial Biotechnology
Electronic Journal of Biotechnology ISSN: 0717-3458 Vol. 13 No. 3, Issue of May 15, 2010
© 2010 by Pontificia Universidad Católica de Valparaíso -- Chile Received July 27, 2009 / Accepted November 10, 2009
DOI: 10.2225/vol13-issue3-fulltext-4
RESEARCH ARTICLE

Kinetic analysis and effect of culture medium and coating materials during free and immobilized cell cultures of Bifidobacterium animalis subsp. lactis Bb 12

Hasan Jalili
 Department of Food Science, Technology and Engineering
Faculty of Biosystem Engineering
Agricultural Campus
University of Tehran
Karaj, Iran

Hadi Razavi*
 Department of Food Science, Technology and Engineering
Faculty of Biosystem Engineering
Agricultural Campus
University of Tehran
Karaj, Iran
E-mail: srazavi@ut.ac.ir

Mohammad Safari
 Department of Food Science, Technology and Engineering
Faculty of Biosystem Engineering
Agricultural Campus
University of Tehran
Karaj, Iran

Abdeltif Amrane
 Ecole Nationale Supérieure de Chimie de Rennes
Université de Rennes and
Université Européenne de Bretagne
France

*Corresponding author

Financial support: Department of Food Science and Engineering Faculty of Agricultural Engineering and Technology University of Tehran.

Keywords: Bifidobacterium, immobilization, kinetic models, medium composition.

Abbreviations: 
A: growth-associated product formation coefficient (g lactic and acetic acid g-1 biomass)
B: non-growth-associated product formation coefficient (g lactic and acetic acid g biomass-1)
f: toxic power for product inhibition
h: toxic power for biomass inhibition
KS: monod constant (g lactose L-1)
ms: maintenance coefficient (g lactose g−1 biomass h-1)
p: lactic and acetic acid concentration (g L-1)
p’m: the maximum product concentration above which bacteria does not product acid
pm: the maximum product concentrationa bove which bacteria does not grow (gL-1)
s: substrate concentration (g L-1)
x: biomass concentration (g L-1)
xm: maximum biomass concentration
YP/S: product yield coefficient (g lactic and acetic acid g-1)
YX/S: biomass yield coefficient (g biomass g-1 lactose)
μ: specific growth rate (h-1)
μm: maximum specific growth rate (h-1)
Abstract   Full Text

Microencapsulation technique appears helpful for more protection of Bifidobacteria against acid inhibitory effect. The effect of medium composition and product inhibitory in free cell culture, as well as the effect of the coating materials in immobilized cells, on biomass growth, acid production and substrate utilization kinetics of Bifidobacterium animalis subsp. lactis Bb 12 in uncontrolled batch fermentation was examined. The Monod and the Luedeking and Piret equations with a product inhibition term involving toxic power terms improved model efficiency for both growth and production. The model showed that media and coating materials had an effect on toxic power terms. Cell immobilization had a positive impact on B. animalis culture. Kinetic analysis revealed the permeability of the coating material had a major impact on culture parameters; permeability increased in the following way: Gellan xanthan < Alginate chitosan < K-Carageenan-locust been, and hence growth parameters xm, maximum specific growth rate (h-1) (µm) and monod constant (g lactose L-1) (KS) followed the same trend as well as the linking between growth and production. The link between the microbial environment and cell growth was highlighted by the model. It was shown that for an increasing protect effect of coating materials against environmental deleterious factors, namely a decrease of the permeability, transport limitation occurred, which was disadvantageous for cell formation.
Supported by UNESCO / MIRCEN network