The Influence of Temperature and Pressure Perturbations on the Dynamics of Bacterial Cell Processes
A. Aristides YAYANOS*
University of California San Diego, Scripps Institution of Oceanography, 9500 Gilman Drive; Department 0202, La Jolla, California 92093-0202, USA
A bacterial cell is composed of small and large molecules. Many of the large molecules are organized into structural components such as membranes and ribosomes. Mechanisms of adaptation of deep-sea bacteria to diverse environmental conditions of temperature and pressure are manifested in intracellular solute composition and in macromolecular and cellular structures. Comparisons of the structure, stability and performance of macromolecules and membranes from bacteria grown under widely divergent conditions of temperature and pressure show differences suggesting mechanisms of adaptation. Concepts such the homeoviscous hypothesis of membrane adaptation have grown in importance through comparative studies of this kind. Other studies, however, conclude only that structural differences between the macromolecules of a thermophile and a psychrophile are subtle.
Thus a complete picture of adaptation to different temperatures and pressures has not emerged. The adaptation of a bacterial isolate to given conditions of temperature and pressure is evident in its PTk diagram〜 a three-dimensional plot of the growth rate constant, k, as a function of temperature, T, and pressure, P. Here I review several modeling approaches described in the literature and discuss the beginning of an effort to develop a mathematical model of a bacterial cell. The ultimate goal is to model the deep-sea bacterial cell as a dynamical system responding to changes in temperature and pressure. One test of the model will be how well it reproduces the PTk diagram of a given bacterial strain.
