Monday, November 9, 2009
P4
Microcalorimetry allows to elucidate effectively quantitative peculiarities of growth of bacteria in colonies of solid state matrices – study and optimize solid-state fermentation processes
Raivo Vilu, Natalja Kabanova, Tiina Krišciunaite, and Irina Stulova. Chemistry, Competence Center of Food and Fermentation Technology, Tallinn University of Technology, Akadeemia tee 15B, Tallinn, Estonia
Growth of Lactococcus lactis IL1403 in solid agarose gels and liquid broth at glucose concentrations of 2, 10 and 20 g L-1 was studied using microcalorimetry TAM III. At each glucose concentration inoculation rates from 100 to 106 cfu mL-1 with the increment of 10 were investigated. Growth in solid agar gels was monitored using microcalorimeter in combination with HPLC and pH measurements, in addition plate count and OD (optical density) measurements were carried out in case of liquid cultures. Maximum specific growth rates (µmax, W h-1), yield coefficients (YXS, g g-1; YQ, J cfu-1), heat produced during the growth (Q, J), duration of lag–phases (λ, h), etc. were calculated in the case of liquid cultures as reference parameters for the bacteria. Growth rates and growth laws of the colonies of different sizes were determined in solid-state fermentations on the basis of the analysis of continuous highly reproducible calorimetric power-time curves in the case of different inoculation rates at different glucose concentrations. Changes of pH and lactic acid concentrations together with density and geometry of colonies were identified as factors determining the peculiarities of growth of colonies of different size in different environmental conditions. A model of multistage growth of a typical colony of Lactococcus lactis in agar gel was developed. The results obtained showed that microcalorimetry used in combination with other relevant measurements is a very powerful instrument in studying solid state fermentations, and could be applied successfully for the study and optimization of industrial solid-state fermentation processes.
See more of Poster Session/Exhibits open
See more of Posters
See more of RAFT VIII (November 8 - 11, 2009)
See more of Posters
See more of RAFT VIII (November 8 - 11, 2009)