Characterization of potential probiotic and postbiotic lactic acid bacteria isolated from sourdough

Abstract

Fermentative lactic acid bacteria (LAB) from sourdough have been studied due to their technological and functional properties. LAB isolates from fermented food, such as sourdough, can have both probiotic and postbiotic potential. This work aimed to evaluate the probiotic and postbiotic potential of 18 LAB isolates obtained from spontaneous sourdough fermentation (BIOTEC collection) and compare them to commercial probiotic Limosilactobacillus reuteri DSM 17938. The probiotic screening was done with auto- and co-aggregation, antibiotic susceptibility, antimicrobial activity, and resistance to simulated digestion tests. Results suggest that the probiotic properties of the BIOTEC isolates are comparable to those of L. reuteri DSM 17938. Companilactobacillus paralimentarius BIOTEC031 excelled in all probiotic property assays. According to statistical analysis, 8 selected isolates exhibited representative probiotic properties of the BIOTEC isolates studied. From the selected BIOTEC isolates, live, pasteurized, and sterilized freeze-dried formulations at 40 mg/mL were prepared. The antioxidant and anti-inflammatory capacity of the 24 formulations was evaluated with ABTS inhibition, DPPH inhibition, in vitro hyaluronidase inhibition, and nitric oxide radical scavenging capacity assays. The BIOTEC live, pasteurized, and sterilized formulations exhibited antioxidant and anti-inflammatory activity to a certain extent. However, the inactivated formulations overcame the live formulation, implying their postbiotic potential. The sterilized formulations had the highest percentages. Companilactobacillus paralimentarius BIOTEC033 in its pasteurized and sterilized forms performed notably well. It is hypothesized that the inactivation method can affect an isolate’s biological activity, is certain properties were enhanced after heat treatment. However, more research and clinical evidence are needed to categorize the LAB BIOTEC isolates as probiotics or postbiotics. Nevertheless, the BIOTEC isolates and their freeze-dried formulations have potential applications in the food, supplement, nutraceuticals, cosmetics, and pharmaceutical industries.