As next-generation probiotics: acetic acid bacteria isolated from Kombucha beverages produced with Anatolian hawthorn leaves.

Abstract

This research examined acetic acid bacteria (AAB) isolated from Kombucha beverages produced with Anatolian hawthorn (Crataegus orientalis) as next-generation probiotics. Eighty-six AAB were isolated from the samples and investigated in terms of biosafety, viability in vitro gastrointestinal conditions, technological and bioactive properties, and also in vitro adhesion abilities. Seventy-six isolates demonstrating γ-hemolysis exhibited resistance to erythromycin and ampicillin. Besides, these isolates survived at low pH and in the presence of bile salts. However, the majority of AAB isolates showed tolerance to phenol, pepsin, and pancreatin. Also, twenty-one isolates showed protease enzyme activity, while eight isolates had amylase enzyme activity. Despite most of the isolates showed viability at 1.5% salt, only 19 isolates survived at 10% salt. Most AAB isolates exhibited inhibition zones ranging from 8 to 26mm against test bacteria, their antioxidant activities were above 80%. Additionally, some isolates exhibited auto-aggregation ability ranging from 0.66 to 23.62% and co-aggregation ability ranging from 1.18 to 71.32%, while hydrophobicity ranged from 1.32 to 69.87% toward xylene. Finally, the indigenous 76 AAB isolates that had remarkable probiotic properties were characterized based on 16S rRNA gene sequencing, and the isolates belonged to Komagateibacter sp. (64.47%), Komagateibacter saccharivorans (15.79%), K. rhaeticus (11.84%), and Gluconobacter sp. (7.90%). As a result, the isolates identified as Gluconobacter sp. A21, Komagataeibacter sp. A139, Gluconobacter sp. A141, and Komagataeibacter sp. A146, which showed high viability under gastrointestinal conditions, safe and acceptable in terms of technological, bioactive, and adhesion properties and could be evaluated as next-generation probiotics.