Wheat endophytic lactobacilli drive the microbial and biochemical features of sourdoughs

The aim of this study was to assess whether wheat endophytic lactic acid bacteria (LAB) are able to dominate in sourdough ecosystem. To do that, a first experimental phase considered doughs produced under semi-sterile conditions and singly inoculated with different strains of endophytic LAB and Lactobacillus sanfranciscensis A4 isolated from sourdough. Notwithstanding the high frequency of Lactobacillus plantarum in the sourdoughs prepared in laboratory, only one of the starter strains, L. plantarum LB2, was detected after five days of back-slopping. Subsequently, the ability of this strain to dominate traditional sourdoughs was evaluated at bakery and laboratory level. Contamination of sourdoughs with L. plantarum LB2 caused an increased number of LAB and, accordingly, higher acidification, compared to the sourdoughs before this event. After six days of propagation, the wheat endophytic strain L. plantarum LB2 was retrieved as a component of the bacterial population, in all the sourdoughs and regardless of the place of propagation. In addition, the contamination event caused a modification of the lactic acid bacterium biota, which in turn influenced some sourdoughs biochemical features. In conclusion, this study showed that wheat endophytic LAB could represent a potential reservoir for selecting robust strains to be used as sourdough starters.