BackgroundOwing to its antimicrobial properties dietary tannins may alter the functional efficacy of probiotic lactobacilli in the gastrointestinal (GI)-tract influencing their growth, viability and molecular adaptation to the intestinal environment.Methods and FindingsThe effects of tannic acid on Lactobacillus plantarum WCFS1 were studied by in vitro growth monitoring and visualizing the morphological alteration on the cell wall using transmission electron microscopy. Growth upon tannic acid was characterized by dose-dependent reductions of initial viable counts and extended lag phases. Lag phase-cells growing upon 0.5 mM tannic acid were abnormally shaped and experienced disturbance on the cell wall such as roughness, occasional leakage and release of cell debris, but resumed growth later at tannic acid concentrations high as 2.5 mM. To gain insight on how the response to tannic acid influenced the molecular adaptation of L. plantarum to the GI-tract conditions, gene expression of selected biomarkers for GI-survival was assessed by RT-qPCR on cDNA templates synthetized from mRNA samples obtained from cells treated with 0.5 or 2 mM tannic acid. Tannic acid-dependent gene induction was confirmed for selected genes highly expressed in the gut or with confirmed roles in GI-survival. No differential expression was observed for the pbp2A gene, a biomarker negatively related with GI-survival. However PBP2A was not labeled by Bocillin FL, a fluorescent dye-labeled penicillin V derivative, in the presence of tannic acid which suggests for enhanced GI-survival reportedly associated with the inactivation of this function.ConclusionsProbiotic L. plantarum WCFS1 is able to overcome the toxic effects of tannic acid. This dietary constituent modulates molecular traits linked to the adaptation to intestinal environment in ways previously shown to enhance GI-survival.

24It was shown that high hydrostatic pressure (HHP) induces either starch gelatinization or protein 25 aggregation in chickpea flour (CF) slurries. The aim of this work was to develop a new "ready-26 to-eat" semi-solid CF product by using HHP at 600 MPa and 50 °C for 15 or 25 min combined 27 with final microwave heating prior to consumption. Eight combinations with a formulation that 28 includes raw or toasted CF, with or without lemon juice, were evaluated using physicochemical 29 (color and protein content, mechanical and rheological behavior), microbiological and sensory 30 analyses. All the CF products were microbiologically safe and stable during two months at 31 refrigerated storage. Mainly, the HHP-treated CF products differed in their texture depending on 32 the CF used, the holding time and the presence of lemon juice, whereby each individual product 33 could be classified as a CF purée or a cream. Moreover, all the formulations showed similar very 34 high sensory quality. 35