[The role of microRNA in abiotic stress response in plants].

Regulation of gene expression via microRNA is the key mechanism of response to biotic and abiotic stresses in plants. There are a lot of experimental data on the biological function of microRNAs in response to different stresses in various plant species. This review contains up-to-date information on molecular mechanisms of microRNA action in plants in response to abiotic stresses, including drought, salinity, mineral nutrient deficiency or imbalance.

[Genetic identification and study of the ability of lactobacilli isolated from the oral cavity of healthy individuals to form biofilms].

The highly antagonistic lactobacillus strains isolated from the oral cavity of human individuals were genetically passported as L. fermentum 39, L. rhamnosus 50, and L. rhamnosus 24, by applying the RAPD-PCR technique with two types of primers (M13, MSP). These lactobacillus strains showed high degrees of autoaggregation, surface hydrophobicity, coaggregation, and adhesion. These characteristics determine the obvious capacity of lactobacilli to form biofilms, which may be used to design new probiotic agents.

[Classification of domestic probiotic cultures of Lactobacillus genus].

AIM: To study strains of bacteria from Lactobacillus genus using combination of microbiological and molecular biological methods in order to define more accurately their systematic position and biochemical characteristics. MATERIALS AND METHODS: Thirteen cultures of Lactobacillus bacteria isolated from stool of healthy persons were studied: L. plantarum CS 396, L. plantarum 8-PA-3, L. plantarum 421-2, L. fermentum 90-TC-4, L. delbrueckii gKNM 101, L. delbrueckii gKNM 526, L. acidophilus Er 317/402 NARINE, L. acidophilus 100 ash, L. acidophilus NK-1, L. acidophilus NNIE, L. acidophilus K3sh24, L. brevis gKNM 23 11, L. casei gKNM 577. Their enzymatic activity relative to 50 sugars was studied using API-50 system. Structure of proximal region of 16S rRNA gene was studied also. RESULTS: According to results of 16S rRNA gene sequence analysis strains were divided on 2 groups: 1) L. casei gKNM 577, L. plantarum 8-PA-3, L. plantarum CS 396, which species belonging corresponded to stated description. Comparison of nucleotide sequence of 16S rRNA gene of group 2 strains with nucleotide sequences database revealed that cultures NK-1, Er315/402 NARINE, 100 ash, NNIE identified early as L. acidophilus belong to species L. helveticus; L. brevis gKNM 23 and L. acidophilus K3sh24--to group L. casei/paracasei, L. delbrueckii gKNM 101 and L. fermentum 90-TC-4--to L. plantarum, L. delbrueckii gKNM 526--to L. fermentum, and L. plantarum 421-2--to L. rhamnosus. CONCLUSION: Obtained data allowed to perform taxonomic reclassification of species belonging of studied probiotic cultures of lactobacilli according to modem level of systematic of bacteria.

[Revised classification of native probiotic strains of Lactobacillus used in Russian Federation].

Thirteen strains of industrial bacterial cultures of the genus Lactobacillus (from a collection of Gabrichevsky Research Institute of Epidemiology and Microbiology) were studied. These strains were used for decades in Russian Federation for food and drug production, as ferments for lactic acid products, for production of probiotics, biologically active and veterinary preparations. Complex analysis of data on cultures obtained using microbiological and molecular-genetic methods was conducted for the first time. Biochemical characteristics of these cultures were studied and the sequence of the proximal region of 16S ribosomal RNA gene was determined. The employment of the test system API-50CHL was shown to broaden the opportunities of a more accurate biochemical identification of bacteria belonging to the genus Lactobacillus, in comparison with the set ANAEROTEST-23. According to the results obtained in a comparative analysis of nucleotide sequences of 16S rRNA gene, all strains examined show 97-99% homology of the proximal region of this gene with that of the type representatives of studied species. These data allowed taxonomic reclassification of the species position of cultures with consideration of the more advanced level of systematics. Nucleotide sequences of gene fragments of examined lactobacilli strains were recorded in NCBI database (accession numbers of deposits GU560031, GU560032, GU560033, GU560034, GU560035, GU560036, GU560037, GU560038, GU560039, GU560040, GU560041, GU560042, GU560043).

[Genetic diversity of the genus Lactobacillus bacteria from the human gastrointestinal microbiome].

The species and strain genetic diversity of bacterial cultures belonging to the genus Lactobacillus, which were isolated from the gastrointestinal microbiome of the human population living in the former Soviet Union in the years 1960-1980, was studied. The bacteria demonstrated probiotic characteristics. Phylogenetic analysis of sequences of the gene coding for 16S rRNA detected earlier by us, showed that the gene found in bacteria isolated from the intestinal content of healthy adults and represented by species L. plantarum, L. helveticus, L. casei/paracasei, L. rhamnosus, and L. fermentum has high homology (97-100%) with this gene in type representatives of the species. The genotypic and strain diversity of cultures was studied using RAPD-PCR and nonspecific primers. This method with the use of the ERIC-1 primer gave reliable and reproducible results as compared that using with M13 and MSP primers and allowed the identification of examined bacteria belonging to the genus Lactobacillus at the level of species and certification at the strain level.

[Genetic identification of antagonistically active lactobacillus strains isolated from the oral cavity of healthy individuals].

Examination of dental deposits from 45 healthy individuals detected 3 lactobacillus strains showing a high antagonism toward test cultures. The api 50 CH "bio Merieux" test systems were employed to identify strains as Lactobacillus fermentum 39, Lactobacillus rhamnosus 24 and Lactobacillus paracasei 50. The results of analyzing the sequences of the 16S rRNA genes of the test strains confirmed this identification, except for the latter strain. The taxonomic status of the third strain L. rhamnosus 50 was determined by the bioinformative analysis of the nucleotide sequence of the 16S rRNA genes.