Change in quantity of lipids and cell size during intracytoplasmic membrane formation in Gluconobacter oxydans

Abstract

Electron microscopy previously revealed that Gluconobacter oxydans differentiates by forming quantities of intracytoplasmic membranes at the end of exponential growth. It was also shown that the formation of these membranes appears concurrently with an increased rate of polyol oxidation. In the present study, exponential-phase cells devoid of intracytoplasmic membranes were harvested and the quantity of free lipid was determined. This quantity was compared with that extracted from cells harvested 4 and 16 h into the stationary phase that contained intracytoplasmic membranes. Cells harvested 4 and 16 h into the stationary phase contained 58 and 43% more free lipid per 100 mg of cell weight than found in undifferentiated exponential-phase cells. These same cultures were used to compare the quantity of lipid extracted per cell. This analysis revealed 89 and 142% more lipid per cell in 4 and 16 h stationary-phase cells. Further study demonstrated that cells increased in length a,nd decreased in density with time after they entered the stationary phase. We estimated, however, that intracytoplasmic membrane development in G. oxydans is accompanied by a 57 to 62% increase in free lipid that cannot be attributed to a change in cell size. These results suggest that the traditional expression of extracted lipid per milligram of cellular dry weight should not be used for comparative purposes during differentiation in gram-negative bacteria, unless it is first established that both cell size and cell density remain constant throughout differentiation.

Effect of Intracytoplasmic Membrane Development on Oxidation of Sorbitol and Other Polyols by Gluconobacter oxydans

“…Other evidence, however, does not entirely support this assumption. Earlier work with glycerolgrown cells showed that a 60% increase in polar lipids accompanied intracytoplasmic membrane development (18). Therefore, we assume that this represents a 60% increase in cellular membranes and their respiratory proteins.…”

“…For cells to have greater respiration rates at a time when their energy needs were decreasing seemed to contradict the idea that limited oxidation functioned solely for energy generation. We found that this increase in oxidative activity was paralleled by the formation of intracytoplasmic membranes (3,7) and an increase in cellular phospholipids (18). Evidenced from thin sections (7) and qualitative fatty-acid analyses (19) strongly suggested that these intracytoplasmic membranes resulted from continued synthesis and subsequent convolution of the plasma membrane after cell division stopped.…”

“…However, we were aware that alternate explanations were also possible. For example, all of our previous studies (3,7,18,19) used glycerol-grown cells, and it was conceivable that continued phospholipid and plasma membrane synthesis occurred only when cells were grown in media containing glycerol. It was also possible that increased respiration rates were due to increased quantities of soluble polyol dehydrogenases or caused by changes in allosteric controls as cells shifted from exponential growth to the stationary phase.…”

Lipid and fatty acid composition of Gluconobacter oxydans before and after intracytoplasmic membrane formation

“…thesis, Virginia Polytechnic Institute and State University, Blacksburg, 1975). Heefner and Claus recently demonstrated that the formation of intracytoplasmic membranes was accompanied by a 57 to 62% increase in extractable lipid (16). The major purpose of the following study was to determine the effect of intracytoplasmic membrane synthesis on the lipid composition of G. oxydans.…”

FOOD GRADE OXYGEN REDUCING MEMBRANE BOUND ENZYMES 1

“…These limited oxidations are accomplished by relatively nonspecific dehydrogenases that are bound to the plasma membrane of the cells (DeLey and Kersters 1964). The occurrence of intracytoplasmic membranes in stationary-phase of Gluconobacter and their absence in exponential growth of cells strongly suggested that inner membrane is being synthesized at the end of exponential growth (Heefner and Claus 1976). Heffner and Claus (1976) also reported that the lipid content of intracytoplasmic membrane increased by 57-62% and could not be attributed to a change in cell size when cells reached stationary phase.…”