VISCOUS POLYSACCHARIDE AND STARCH SYNTHESIS IN RHODELLA RETICULATA (PORPHYRIDIALES, RHODOPHYTA) 1

ABSTRACT Rhodella reticulata Deason, Butler and Rhyne produces copious amounts of a viscous polysaccharide (VP) during growth in batch cultures. The VPs accumulated on the cell surface and in the culture medium once cells ceased growth; starch concurrently accumulated within the cells. Light‐saturated 14 C‐uptake declined steadily as the cells aged. Net synthesis rates for starch and mucilage were two‐ and four‐fold lower, respectively, in non‐growing cells than in growing cells, while the relative partitioning of newly‐fixed carbon into these materials was not different. These data suggest that total photosynthetic loading, rather than partitioning into one specific pool, controls cellular synthesis rates. No preferential synthesis of VPs occurred during the stationary phase. The findings have important implications for the commercial production of VPs.