Bacterial “Glycogen” and Survival

Abstract

IN certain conditions, bacteria accumulate relatively large amounts of polyglucose compounds with properties similar to those of animal glycogen¹. An interpretation of bacterial “glycogen” production is that it provides a food and/or energy reserve for the organisms in unfavourable environments; in other words, bacteria rich in glycogen should survive longer than bacteria without such reserves. Experimental results apparently supporting this teleological interpretation were obtained with Aerobacter aerogenes² and Escherichia coli³ but not with Sarcina lutea⁴; glycogen-rich S. lutea died at a faster rate than cells without glycogen during starvation in aerated phosphate buffer at 37° C. A feature of glycogen reserves in bacteria is their rapid depletion during starvation which suggests that any contribution glycogen makes towards maintenance and survival is of short duration⁵. It is possible that growth conditions which stimulate the accumulation of glycogen give rise to bacteria better able to resist stress for reasons not concerned with their glycogen content. The effect of glycogen reserves on bacterial survival was examined with E. coli; cells containing different amounts of glycogen were grown in a chemostat and their survival properties were determined in aerated saline phosphate buffer with and without magnesium at 37° and 48° C.