Acta Scientiarum Polonorum Technologia Alimentaria

Background. Lactic acid bacteria (LAB) play an important role in the gastrointestinal tract (GIT) of humans and animals. They control the entrance of undesirable microorganisms and support intestinal defense. As well as typical representatives of Lactobacillus genera in GIT, other LAB strains, which come from fermented foods, can sometimes be found. The objective of this study was the investigation of autoaggregation, coaggregation, hydrophobicity, antibiotic resistant and enzymatic activity of LAB isolated from fecal and fermented foods in vitro.
Material and methods. Bacterial isolates were analyzed to determine the survival of LAB in conditions prevailing in the GIT, lipolytic and proteolytic activity, resistance to antibiotics, autoaggregation, coaggregation and hydrophobicity. All genetic analyses were conducted with qualitative real-time PCR.
Results. In this study, 70 isolates were investigated as putative probiotic candidates. 35 isolates each were isolated from fermented foods and feces. Isolates were identified as L. rhamnosus, L. plantarum, L. casei, L. acidophilus, L. delbrueckii, and L. brevis. The ability to survive in pH = 3.0 was displayed by 22 out of the 35 isolates from fermented products, whereas 20 isolates survived in MRS with 7% NaCl. Survivability in an environment after the addition of bile salts was confirmed for 26 isolates. All isolates from feces were resistant to pH = 3.0, 1% bile salt, and 7% NaCl. Among the 70 analyzed isolates only 3 showed lipolytic activity, whereas as many as 65 exhibited proteolytic activity. Of the 70 isolates tested, the largest number of isolates was characterized by average values in the hydrophobicity, autoaggregation, and coaggregation tests. All isolates were found to be resistant to vancomycin and metronizadole.
Conclusions. Lactobacillus spp. isolates from the analyzed environments were found to be able to survive at low pH values and in the presence of bile salts. The dominant species among the isolates were Lactobacilus casei and Lactobacillus acidophilus.