The objective of the research study was to isolate and identify acetic acid strains (AAB) in the polyphasic system and to in vitro predefine their potential probiotic properties under the laboratory conditions. The material for the isolation of acetic acid strains were seasonal fruits from local crops in the Mazovian and Łódź provinces and a starter culture for the production of Kombucha. The strain identification was carried out using a polyphasic system based on the morphological profile, biochemical abilities and genetic identification. Based on the results obtained, an AAB strain collection was created that were safe for the human health. Next, there was determined the antibiotic susceptibility to 12 selected bacteria killing substances and the tests were performed of in vitro survival of selected strains under the conditions of a model human gastrointestinal tract. Based on the phenotype analysis and the sequencing of the 16S rRNA gene from among 9 isolates of AAB, 3 strains belonging to Gluconobacter oxydans species were selected: H31 isolated from black currant, and H30 and H32 from the starter culture for the production of Kombucha tea. It was found that two strains, G. oxydans H30 isolated from Kombucha and G. oxydans H31 from black currant, were characterized by a good survival rate at a level of 6 log CFU/ml while passing through the model human digestive system and thus they met one of the basic criteria for potentially probiotic bacteria. All the strains analysed showed the similar antibiotic susceptibility. The conducted diagnostics of selected acetic acid bacterial strains constitutes a basis for further studies of those microorganisms for the purpose of confirming other probiotic features.
acetic acid bacteria (AAB), probiotics, in vitro survival, fruits, Kombucha