Nutrient Deficiency Promotes the Entry of Cells into Yeast Cells.

, a Gram-negative bacterium, has as a natural niche the human gastric epithelium. This pathogen has been reported to enter into yeast cells; however, factors triggering this endosymbiotic relationship remain unknown. The aim of this work was to evaluate in vitro if variations in nutrient concentration in the cultured medium trigger the internalization of within cells. We used - co-cultures in Brucella broth supplemented with 1%, 5% or 20% fetal bovine serum or in saline solution. Intra-yeast bacteria-like bodies (BLBs) were observed using optical microscopy, while intra-yeast BLBs were identified as using FISH and PCR techniques. Intra-yeast (BLBs) viability was confirmed using the LIVE/DEAD BacLight Bacterial Viability kit. Intra-yeast was present in all combinations of bacteria-yeast strains co-cultured. However, the percentages of yeast cells harboring bacteria (Y-BLBs) varied according to nutrient concentrations and also were strain-dependent. In conclusion, reduced nutrients stresses , promoting its entry into cells. The starvation of both and strains reduced the percentages of Y-BLBs, suggesting that starving yeast cells may be less capable of harboring stressed cells. Moreover, the endosymbiotic relationship between and is dependent on the strains co-cultured.