Adaptation and Probiotic Potential of Lactobacilli, Isolated from the Oral Cavity and Intestines of Healthy People Yulia Chervinets 1 & Vyacheslav Chervinets 1 & Boris Shenderov 2 & Ekaterina Belyaeva 1 & Andrey Troshin 1 & Sergey Lebedev 1 & Valery Danilenko 3 # Springer Science+Business Media, LLC, part of Springer Nature 2017 Abstract The present study shows that, from 300 Lactobacillus strains isolated from the oral cavity and large intestine of 600 healthy people, only 9 had high antagonistic activity against pathogens and opportunistic pathogens. All antagonistic strains of lactobacilli have been identified by 16S rRNA sequencing and assigned to four species: Lactobacillus fermentum, Lactobacillus rhamnosus, Lactobacillus plantarum, and Lactobacillus casei. In addition, these lactobacilli appeared to be nonpathogenic and had some probiotic potential: the strains produced lactic acid and bacteriocins, showed high sensitivity to broad-spectrum antibiotics, and were capable of forming biofilms in vitro. With the help of PCR and specific primers, the presence of genes for prebacteriocins in L. plantarum (plnEF , plnJ, plnN) and L. rhamnosus (LGG_02380 and LGG_02400) has been revealed. It was found that intestinal strains of lactobacilli were resistant to hydrochloric acid and bile. Lactobacilli isolated from the oral cavity were characterized by a high degree of adhesion, whereas intestinal strains were characterized by average adhesion. Both types of lactobacilli had medium to high rates of auto-aggregation and hydrophobicity and could coaggregate with pathogens and opportunistic pathogens. Additionally, the ability of the lactobacilli strains to produce gasotransmitters, CH 4 , CO 2 ,C 2 H 6 , CO, and NH 3 , has been revealed. Keywords Lactobacilli . Oral cavity . Adhesion . Acid production . Persistence . Gasotransmitters Introduction It is known that the microbial consortia, which colonize the mucosa of different niches within the gastrointestinal tract (GIT), constantly interact with each other and with the neuro- humoral and immune systems of the human organism [1, 2]. Therefore, the symbiotic microbial community of the GIT is considered to be a Btuning fork,^ responsible for the somatic status, stress, and mood of a person [3]. Lactobacilli species, being representatives of the normal microbiota of the human body and colonizing various biotopes, participate in protective mechanisms within the GIT [4–6]. Previous papers have al- ready shown the effectiveness of the use of lactobacilli (Lactobacillus acidophilus and Lactobacillus rhamnosus) in the treatment and prevention of diarrhea caused by emerging infectious diseases and antibiotic treatments [ 7 , 8 ]. Additionally, the positive effect of Lactobacillus rhamnosus GG was observed in the prevention of colorectal cancer [9] and the treatment of irritable bowel syndrome [10, 11]. Different strains of lactobacilli were reported as effective in the prevention and treatment of viral diarrhea [12, 13], inflam- mation of the mucous membranes of the stomach and small intestine caused by Helicobacter pylori, as well as obesity [14–18]. Results of recent clinical trials suggest that probiotic supplementation reduces the risk of necrotizing enterocolitis caused by Clostridium difficile in premature infants [19]. Moreover, probiotic strains of lactobacilli have positive effects in the prevention and treatment of bacterial vaginosis and other emerging infectious diseases of the urogenital tract [20–22], caries [23], and allergic diseases [24]. Furthermore, many lactobacilli have an antagonistic effect on various path- ogenic strains [25] and can restore GIT homeostasis by regu- lating inter-microbial relations, improving the resistance of the intestinal epithelium barrier, and activating the monocyte– macrophage system. Lactobacilli can stimulate the differenti- ation of T cells towards suppressive and cytotoxic phenotypes, * Yulia Chervinets julia_chervinec@mail.ru 1 Department of Microbiology and Virusology with Immunology course, Tver State Medical University, Tver, Russia 2 Laboratory of Biology of Bifidobacteria, Moscow Research Institute of Epidemiology and Microbiology named by G. N. Gabrichevsky, Moscow, Russia 3 Laboratory of Genetics of Microorganisms, Institute of General Genetics named by N. I. Vavilov of the Russian Academy of Sciences, Moscow, Russia Probiotics and Antimicrobial Proteins https://doi.org/10.1007/s12602-017-9348-9