Growth of bacteria Lactococcus lactis IL1403 in broth was studied using microcalorimeter in combination with H PLC, plate count, pH and OD (optical density) measurements. On the basis of the calorimetric data maximum specific growth rate (mu(max), W h(-1)), yield coefficients (Y-XS, g g(-1); Y-Q, J cfu(-1)), produced heat (Q, J), lag-phase duration (lambda, h), etc. were calculated for the bacteria. Power-time curves measured allowed to analyze growth curves as consisting of two phases-exponential phase and "deceleration phase". Active growth of biomass/active metabolic processes are taking place during the exponential phase of growth, and the second, "deceleration phase" combines the stationary phase of bacterial growth curve together with the deceleration of the metabolism of bacteria. The numerical data obtained for the analysis of the bacterial growth in broth form a necessary basis for further studies of L. lactis using calorimetric method. (C) 2009 Elsevier B.V. All rights reserved.