Flow microcalorimetry investigation of the influence of glucose and maltose on the growth of Streptococcus agalactiae and the production of CAMP factor (protein B)

Abstract

Microcalorimetric investigations of the growth of Streptococcus agalactiae and production of CAMP factor were performed in combination with the photometric estimation of bacterial mass and the bioluminescent measurement of extracellular ATP in trypticase peptone-yeast extract broth supplemented with either 2% maltose or glucose. Maltose was found to be a more efficient energy substrate than glucose, providing more energy and C-atoms to the growing cells. In the presence of maltose, the metabolic activity of S. agalactiae was more efficient and better balanced than in that of glucose. Bacterial cells growing in maltose-containing medium used more substrate energy for their anabolic activities, while cells growing in the presence of glucose lost more substrate energy in the form of heat. The addition of 0.2% NaHCO3 to the carbohydrate-supplemented medium enhanced the efficiency of the anabolic activity of growing cells, but did not promote bacterial growth. Microcalorimetry should be considered as a useful alternative as well as a complementary method for the optimization of the growth media or growth conditions.