Synthesis and Breakdown of ß-L,3-Glucan in Euglena Gracilis During Growth and Carbon Depletion

Abstract

Cellular levels of the reserve carbohydrate of the Z strain of E. gracilis, f3-1,3-glucan (paramylon), were determined during heterotrophic growth in the dark and in the light. During growth in the dark the f3-1,3-glucan content exceeded 6 mg per 107 cells, but most of this was not readily available for cell growth and division. Towards the end of the growth phase the f3-1,3-glucan content fell to 2-4 mg per 107 cells but the total f3-1,3-glucan content of the culture remained about the same. After division stopped the f3-1,3-glucan was utilized only slowly. Similarly, when rapidly growing cells were transferred to a medium lacking a source of carbon for growth, cell division continued for several hours but ceased when the f3-1,3-glucan content had fallen to about 2 mg/107 cells.