Intracellular substrates for endogenous metabolism during long-term starvation of rod and spherical cells of Arthrobacter crystallopoietes

Abstract

Cells of Arthrobacter crystallopoietes, harvested during growth as spheres and as rods, were starved by shaking at 30 C in phosphate buffer for 30 days, during which time they maintained 100% viability. Changes in cellular components and the activity of specific enzyme pathways were monitored. A glycogen-like polysaccharide comprised 40% of the dry weight of growing spherical cells and 10% of the dry weight of rod cells. This material was utilized at approximately the same rate, on a percentage basis, during starvation of both cell forms. The rods degraded intracellular protein at approximately twice the rate of the spheres. At the end of 30 days, the rods had degraded 40% and the spheres 20% of their initial content of protein. Ribonucleic acid (RNA) was degraded significantly more rapidly in the rods. After 30 days starvation, 85 and 32% of the initial RNA of rods and spheres, respectively, had been depleted. Magnesium ion followed this same general pattern; the rods lost 65% and the spheres 45% of their initial content during 28 days of starvation. Deoxyribonucleic acid increased by 20% during the first few hours of starvation of both cell forms and then remained constant. The ability of glucose-, succinate-, and 2-hydroxypyridine (2-HP)-grown cells to oxidize glucose remained constant during 14 days of starvation. The ability of succinate-grown cells to oxidize succinate decreased rapidly during the first few hours of starvation to a rate which remained constant for 14 days. Cells adapted to growth on 2-HP completely lost their ability to oxidize this substrate after 3 days starvation.