Stati di crescita stazionari e transitori di una coltura batterica

Ageno, Mario ; Salvatore, Anna Maria ; Vallerani, Daniela

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 80 (1986) no. 4, pp. 244-255

Résumé

Balanced growth is currently considered a fundamental concept in the description and the theory of the bacterial cell cycle. Bacterial growth curves in liquid minimal medium, obtained in severely controlled growth conditions and which cannot be interpreted in terms of the above concept are presented in this paper. If point to point differences in growth conditions in the culture are carefully avoided, the culture growth is always exponential. However the growth rate of the optical density and of the colony number on agar plates are often different, showing that the mean bacterial mass is slowly varying. Furthermore, sudden variations of growth rates and sudden transitions from lag to exponential growth and from exponential growth to saturation are observed. The bacterial density reaches saturation 15-30 minutes after the saturation of the optical density. In order to give an account of the results, the concept of stationary and transitory growth states are defined as an introduction to further research work in the organization of the bacterial cell.