A new Leuconostoc citreum strain discovered in the traditional sweet potato sour liquid fermentation as a novel bioflocculant for highly efficient starch production

•Bacterial composition changes in sweet potato sour liquid fermentation were profiled.•Seven isolates showed starch-flocculating abilities with flocculation rates up to 55.56%.•First time to report the starch flocculation functions of Leuconostoc citreum.•Highly efficient starch sedimentation was achieved using new strain L. citreum SJ-57.