Thermochimica Acta, Vol.559, 69-75, 2013
Microcalorimetric study of growth of Lactococcus lactis IL1403 at low glucose concentration in liquids and solid agar gels
Growth of Lactococcus lactis IL1403 in liquid cultures and solid agar gels at different low glucose concentrations starting from 2 g L-1 up to 10 g L-1 with a stepwise increase by 1 g L-1 was studied using thermal activity monitor TAM III. In parallel to calorimetric measurements the changes of glucose and lactic acid concentrations and pH of culture media were measured in order to obtain additional information for the interpretation of calorimetric power-time curves. The data obtained together with calculated heat yield coefficient Y-Q allowed to analyze the growth of bacteria in colonies in solid agar gels in detail. The variation of glucose concentration at low levels allows analyzing and describing growth deceleration phase and growth stopping mechanisms both in liquid cultures and in solid-state fermentations. (C) 2013 Elsevier B.V. All rights reserved.
Keywords:Microcalorimetry;Bacterial growth;Lactic acid bacteria;Lactococcus lactis;Colonial growth;Solid-state fermentations