Fattori limitanti la crescita batterica

Ageno, Mario ; Benini, Massimiliano ; Matricciani, Maria Antonietta

Atti della Accademia nazionale dei Lincei. Rendiconti della Classe di scienze fisiche, matematiche e naturali, Série 8, Tome 80 (1986) no. 6, pp. 447-457

Résumé

The effects of oxygen or glucose starvation on the growth rates and on the saturation levels of a bacterial culture in liquid minimal medium are re-examined. The existence of exponential growth umbalanced growth states and of point-transitions from state to state is confirmed. Growth curves with different oxygen availabilities are compared and the validity of the theoretical formula: $$\Sigma_{i} \tau_{mi} (D_{i} - D_{i-1}) = \text{const.}$$ is examined. Here, $D_{i}$ is the optical density at the ith transition point, $\tau_{mi}$ is the doubling time of the optical density between the (i— 1)th and the ith transition point, and the sum is effected all along a growth curve. The features of the point-transitions are discussed and the conclusion is derived that they might by caused by the switching over of a multimeric enzyme, when some threshold value of the concentration of a normal cellular constituent is reached. The residual glucose concentration in the liquid medium, when the optical density stops growing, is evaluated with two different methods and it is found to be of the order of $1 \div 2$ mg/l.