Indole enhances the survival of Pantoea ananatis YJ76 in face of starvation conditions

Pantoea ananatis YJ76 is an indole-producing predominant diazotrophic endophyte isolated from rice having multiple growth-promoting effects on host plant. As a decomposition metabolite of L-tryptophan (L-Trp), indole is confirmed to regulate various physiological processes of bacteria. In this research, we found that indole significantly improves the survival of YJ76 in face of starvation conditions and the promoting effect is related to the glycogen accumulation promoted by indole, which is much more significant in the middle decline phase than in other growth phases. Since carbon storage regulator CsrA is a key inhibiting factor on the storage of glycogen in bacteria, we explored the relation between indole-enhanced glycogen accumulation and csrA expression and found that there is a positive correlation between indole-enhanced glycogen accumulation and the indole-inhibited csrA expression in YJ76, which implies the potential relation between CsrA regulation and indole regulatory pathway.