Relationship between kinetics of growth and production of exo-electrons: Case study with Geobacter toluenoxydans

Szöllősi, Attila and Narr, László and Kovács, Attila G. and Styevkó, Gabriella (2015) Relationship between kinetics of growth and production of exo-electrons: Case study with Geobacter toluenoxydans. Acta Microbiologica et Immunologica Hungarica, 62 (3). pp. 307-316. ISSN 1217-8950

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Abstract

Kinetics of growth and product formation of G. toluenoxydans DSMZ 19350 strain were investigated using sodium-acetate as substrate and Fe³⁺-ions and fumarate as electron acceptor. Response surface method was adapted for evaluation of growth of bacteria. Results showed that maximum growth was detected in the case of 2.2 g/L substrate concentration. Application of higher substrate concentration (>2.5 g/L sodium acetate) significantly inhibits the bacterial growth. Luong’s model was found to be the most suitable to determine kinetic parameters (μ_max = 0.033 1/h, K_S = 0.205 g/L) of growth of G.toluenoxydans strain, and the growth was completely inhibited at substrate concentration higher than 3.1 g/L. In the case of product formation the Haldane model was used and kinetic parameters are μ_Pmax = 0.123 mg/h, K_PS= 0.184 g/L. Correlation between microbial growth and product formation was observed using the Luedeking–Piret empirical method. Both factors (growth and number of cells) affected significantly iron(III)-reduction, thus the product formation. These results are important and open the possibility to design a continuous MFC setting operating with G. toluenoxydans as biocatalyst.

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