Exogenous folates stimulate growth and budding of Candida glabrata

Folate, vitamin B9, is well recognized as being essential for cell growth. The utilization of folate is common to all cells, but the source of it may be quite different. For example, mammalian cells depend on exogenous uptake of folates, while plants and microbes can synthesize them. There has been little consideration of uptake of folate in microbial cells, and studies on the effects of folates in mammalian cells, where conditions are restricted. This study shows that exogenous folates (folic acid or folinic acid), causes Candida glabrata cells suspended in water alone to undergo two cycles of cell division and to form multiple buds. The effect was limited to cells in the stationary phase and more profound in quiescent cells. These data indicate a novel response of yeast to folates that may increase the utility of yeast as a model to study folate transport and signaling.