Establishing Normative Values to Determine the Prevalence of Biochemical Hyperandrogenism in Premenopausal Women of Different Ethnicities from Eastern Siberia

Androgen assessment is a key element for diagnosing polycystic ovary syndrome (PCOS), and defining a "normal" level of circulating androgens is critical for epidemiological studies. We determined the upper normal limits (UNLs) for androgens in a population-based group of premenopausal "healthy control" women, overall and by ethnicity (Caucasian and Asian), in the cross-sectional Eastern Siberia PCOS Epidemiology and Phenotype (ESPEP) Study (ClinicalTrials.gov ID: NCT05194384) conducted in 2016-2019. Overall, we identified a "healthy control" group consisting of 143 healthy premenopausal women without menstrual dysfunction, hirsutism, polycystic ovaries, or medical disorders. We analyzed serum total testosterone (TT) by using liquid chromatography with tandem mass spectrometry (LC-MS/MS), and DHEAS, sex-hormone-binding globulin (SHBG), TSH, prolactin, and 17-hydroxyprogesterone (17OHP) were assessed with an enzyme-linked immunosorbent assay (ELISA). The UNLs for the entire population for the TT, free androgen index (FAI), and DHEAS were determined as the 98th percentiles in healthy controls as follows: 67.3 (95% confidence interval (CI): 48.1, 76.5) ng/dl, 5.4 (3.5, 14.0), and 355 (289, 371) μg/dl, respectively. The study results demonstrated that the UNLs for TT and FAI varied by ethnicity, whereas the DHEAS UNLs were comparable in the ethnicities studied.

Polycystic Ovary Syndrome and Gut Microbiota: Phenotype Matters

Abnormalities in gut microbiota diversity are considered important mechanisms in metabolic disorders in polycystic ovarian syndrome (PCOS). However, the data on the association of these disorders with the PCOS phenotype remain controversial. The objectives of this study were to estimate the alpha diversity of the gut microbiota of healthy women and PCOS patients depending on phenotype. The study participants (184 premenopausal women: 63 with PCOS, 121 without PCOS) were recruited during the annual employment assessment in the Irkutsk Region and the Buryat Republic (Russia) in 2016-2019. For PCOS diagnosis, we used the Rotterdam (2003) criteria and definitions of PCOS phenotypes. Five indexes of alpha diversity (ASV, Shannon, Simpson, Chao, and ACE) were estimated for the gut microbiota in all participants using amplicon metasequencing. As a result, two out of five alpha diversity indexes showed a statistical difference between the non-PCOS and PCOS groups. We did not find a significant difference in the alpha diversity of gut microbiota in the subgroups of women with hyperandrogenic PCOS phenotypes vs non-androgenic phenotype D and the group of women with the presence of only one of the PCOS criteria. Nevertheless, "classic" PCOS phenotypes demonstrated the most significant decrease in alpha diversity compared with healthy women without any signs of PCOS.

Effects of аntimicrobials on <i>Pseudomonas aeruginosa</i> biofilm formation

Pseudomonas aeruginosa is one of the most problematic pathogens in medical institutions, which may be due to the ability of this microorganism to exist in a biofilm, which increases its resistance to antimicrobials, as well as its prevalence and survival ability in the external environment. This work aimed to evaluate the antimicrobial susceptibility of P. aeruginosa strains in planktonic and biofilm forms. We studied 20 strains of P. aeruginosa collected during 2018–2021 by specialists from the Laboratory of Microbiome and Microecology of the Scientific Centre for Family Health and Human Reproduction Problems. The identification of strains was carried out using test systems for differentiating gram-negative non-fermenting bacteria (NEFERMtest 24 Erba Lachema s.r.o., Czech Republic), and confirmed by mass spectrometric analysis and 16S rRNA gene sequencing. Antimicrobial activity was assessed by the degree of inhibition of cell growth in planktonic and biofilm forms (on a flat-bottomed 96-well plastic immunological plate). All clinical isolates of P. aeruginosa were biofilm formers, 47.6 % of the isolates were weak biofilm formers, and 52.4 % of the isolates were moderate biofilm formers. Planktonic cells and the forming biofilm of the tested P. aeruginosa strains were carbapenems-resistant. Biofilm formation was suppressed in more than 90 % of cases by the agents of the cephalosporin and aminoglycoside groups. Antimicrobial susceptibility of P. aeruginosa strains in the formed biofilm was significantly lower (p < 0.05). Carbapenems and cephalosporins did not affect the mature biofilms of the tested P. aeruginosa strains in more than 60 % of cases. Only non-beta-lactam antibiotics (ciprofloxacin and amikacin) suppressed the growth of planktonic cells and destroyed the mature biofilm. The revealed differences in the effect of the tested antimicrobials on the P. aeruginosa strains biofilms correlate with resistance to a number of antibiotics. To prevent biofilm formation in the hospital strains of P. aeruginosa, the use of ceftazidime may be recommended, and antimicrobials such as ciprofloxacin and amikacin may be used to affect mature biofilms of P. aeruginosa.

Diversity and Metabolic Potential of the Gut Microbiome in Adolescents with Functional Bowel Disorder

The article presents the results of a pilot study of the diversity and metabolic potential of the gut microbiome in adolescents with various forms of functional bowel disorder. The participants were the patients of the Clinic of Research Center for Family Health and Human Reproduction Problems. Biological material was studied using metagenomic sequencing of V3-V4 variable regions of the 16S rRNA gene. We showed that the composition of the minor component of the intestinal microbiome in adolescents with functional bowel disorder differs from that in the healthy subjects (control). Different types of transit disturbances in functional bowel disorder also differ from each other. According to the metabolic potential, adolescents can be divided into two groups irrespective of the pathophysiological manifestations: for one group, a more intensive metabolism in amino acid and lipid biosynthesis pathways was predicted than for the other.

The relationship between the composition of the microbiota and functional intestinal disorders in obese adolescents

Functional gastrointestinal disorders (FGIDs) in children and adolescents are one of the most common pathologies of the digestive tract. The aim of the study was to study the structure of the colon microbiota in obese adolescents and to establish its relationship with the clinical manifestations of the disease FGIDs. The study included 20 adolescents aged 11-17 years. The main group included 13 adolescents with a clinically confirmed diagnosis of obesity (the standard deviation of the body mass index (SDS BMI) is more than 2,0) in combination with FGIDs. The control group consisted of 7 adolescents with normal body weight and no abdominal complaints (SDS BMI=0,66). Clinical symptoms from the bowel re diagnosed on the basis of the Rome IV. The consistency of feces was evaluated using the Bristol Stool Form Scale. The study of biological material was carried out by standard bacteriological methods. It is shown that in adolescents with obesity and FGIDs, there is a decrease in the concentration of representatives of bifidoflora, an increase in the microbial density of Escherichia coli with altered properties and an excessive growth of potentially pathogenic enterobacteria. It is established that the presence of conditionally pathogenic bacteria is sem. Enterobacteriaceae is associated with abdominal pain during defecation. In obese adolescents in the group with unformed stools, Clostridium spp was recorded as part of the intestinal microbiota.

Effect of Disinfectants with Different Active Ingredients on Biofilm Formation in Pseudomonas aeruginosa

We compared the effects of disinfectants on biofilms of 10 Pseudomonas aeruginosa strains isolated from different loci of patients with purulent-septic infections. Identification was carried out by standard bacteriological methods. To substantiate the prospects of using in hospitals and to assess the effect of disinfectants on P. aeruginosa biofilms, the following disinfectants were used in various concentrations: Sekusept Aktiv, A-DEZ, and Monitor Oxy. All clinical strains of P. aeruginosa showed the ability to form biofilms. Both oxygen-containing and quaternary ammonium compounds effectively inhibited the formation of biofilms. In more than 50% cases, disinfectants with different active ingredients did not destroy pre-formed of P. aeruginosa biofilms.

Cellular Immune Response of an Endemic Lake Baikal Amphipod to Indigenous Pseudomonas sp

Studies of invertebrates have shown that the internal environment of crustaceans is not always sterile in normal conditions, and in many species, it can be populated by microorganisms even in the absence of any visible pathological processes in the body. This observation raises the question of whether genetically modified indigenous hemolymph microorganisms can be used for biotechnological purposes inside the crustacean either as local producers of some compounds or as sensors to physiological parameters. In this study, we tested the ability of the bacteria isolated from the hemolymph of the amphipod Eulimnogammarus verrucosus to hide from the cellular immune response of the host as the most important feature for their potential long-term application in vivo. 16S rDNA amplicon sequencing revealed five common bacterial genera in all analyzed samples of the amphipod hemolymph, among which Pseudomonas is most easily subjected to genome modification and, thus, the most prospective for biotechnological application. Cultivation of Pseudomonas gave us a number of strains undoubtedly derived from the amphipod hemolymph, and one of them (belonging to the Pseudomonas fluorescens group) was chosen for further tests. The primary culture of amphipod hemocytes was used to analyze the immunogenicity of the strain and showed a pronounced reaction of the immune cells to a high amount of the bacteria within six hours. This result indicates that modulation of cellular immune response to metabolically active bacterial cells is not mandatory for the survival and wide distribution of these microorganisms in the hemolymph of numerous amphipod individuals.

Еvaluation of the sensitivity of bacteriophage preparations to Klebsiella pneumoniae strains isolated from the colon microbiota in children with functional gastrointestinal disorders

The level of sensitivity of Klebsiella pneumoniae strains isolated from children of the first half of life with functional gastrointestinal disorders (FGID) to commercial bacteriophage preparations was assessed. The material was the feces of 67 children of the first half of life with FGID who are breastfed. Culture of K. pneumoniae isolated from faeces of children, amounted to two comparison groups, depending on the age of the patients. The first group included 43 K. pneumoniae strains isolated from the colon of children aged from birth to three months, in the second group - 24 strains, from children aged three to six months. The composition of the colon microbiota was studied using standard methods, and the results were evaluated in accordance with Industry Standard 91500.11.0004-2003. Identification of K. pneumoniae was performed by bacteriological methods. Determination of the level of lytic activity of K. pneumoniae, Klebsiella polyvalent and sextaphage bacteriophages to K. pneumoniae strains was conducted by the drip method (spot-test) according to clinical recommendations. It is shown that the formation of FGID symptoms in children correlates with age - the frequency of regurgitation decreased in children up to six months (from 23.3% to 4.2%) against the background of the formation of a symptom complex associated with defecation disorder. Bacteriological analysis showed that in General, phages show a low level of lytic activity, sensitivity to them Klebsiella also correlated with age and was higher in children of three to six months. Thus, in the first comparison group, the absence of Klebsiella lysis in relation to the Klebsiella pneumoniae bacteriophage was registered three times more often (30.2%, p<0.05) and twice less often (30.2%, p<0.05), the low level of lysis of K. pneumoniae strains to the Klebsiella polyvalent phage compared to the second group. The sensitivity of K. pneumoniae strains to sextaphage was comparable in comparison groups and varied from 2 to 10%. Thus, among the studied K. pneumoniae observed a low level of sensitivity to specific drugs - bacteriophage Klebsiella pneumoniae, Klebsiella polyvalent and sextaphage. This fact reflects the insufficient activity of phages and predicts low effectiveness of empirical phage therapy without elimination from the intestinal biocenosis of K. pneumoniae in children with FGID who are breastfed.

Metasequencing of V3-V4 Variable Regions of 16S rRNA Gene in Opportunistic Microbiota and Gut Biocenosis in Obese Adolescents

Opportunistic microorganisms in the gut biocenosis were studied in adolescents with normal body weight and obesity (patients consulted at the Clinical Department of Research Center of Family Health and Human Reproduction Problems). The biological material was studied by standard bacteriological methods, representatives of Enterobacteriaceae family were also characterized using metagenomic sequencing of V3-V4 variable regions of 16S gene rRNA. Gut microbiota of obese adolescents was unbalanced and was characterized by low levels of bifido- and lactoflora representatives, a spectrum of E. coli associations, and high prevalence of opportunistic microorganisms and their associations. Representatives of Enterobacteriaceae family were most often found in the gut microbiota of obese adolescents.

Metagenome datasets from women with polycystic ovary syndrome from Irkutsk, Eastern Siberia, Russia

For the metagenomic characterization of potential taxonomic and functional diversity of microorganisms associated with polycystic ovary syndrome (PCOS) in women, we surveyed five women with PCOS and collected samples of feces, saliva, and serum. After quality processing, we have obtained from 915,594 to 3,880,379 reads; these 16,693 sequences had ribosomal RNA genes, 2,091,990 sequences contained predicted proteins with known functions, and 3,750,261 sequences had predicted proteins with unknown functions. Host DNA accounted for ca. 0.03% and less in datasets of fecal samples, from 1.41 to 24.94% in saliva samples; the remaining sequences were attributed to archaeal, bacterial, or viral DNA. In serum, from 38.18 to 75.77% were characterized as fragments of the human genome, but the remaining sequences were unidentified. Among microbes, a total of one archaeal and eight bacterial phyla were revealed. Viral DNA was detected in several fecal and one saliva sample and was classified as C2likevirus, Flavivirus, and Streptococcus bacteriophage. The metagenome sequence data were deposited at NCBI SRA as BioProject No. PRJNA625611.

Metagenomic 16S rDNA amplicon datasets from adolescents with normal weight, obesity, and obesity with irritable bowel syndrome from Eastern Siberia, Russia

Childhood obesity and its consequences are a significant public health problem worldwide. Gut microbiota has a potential role in the development of. In the current datasets, we present 16S rDNA amplicon metasequencing of the gut microbiome of adolescents with normal weight, obesity, and obesity with irritable bowel syndrome (IBS) carried out using the Illumine platform. The datasets presented in this report are partly shown in the research article named “Composition and Structure of Gut Microbiome in Adolescents with Obesity and Different Breastfeeding Duration” [1]. The amplicon metasequencing data were deposited at NCBI SRA as BioProject PRJNA604466. A total of 22 phyla, 34 classes, and 231 genera were revealed. Three groups of adolescents had 196 core amplicon sequence variant (ASV), whereas 45, 24, and 1 ASV were unique for adolescents with normal body weight, obesity, and obesity with IBS, respectively. The metagenomic data were first obtained for adolescents from Eastern Siberian, Russia. They have the potential for predictive analysis, which is crucial for understanding microbial community dynamics and their role in the development of the intestinal microbiome. Considering the recent focus on gut microbiota, new datasets are needed to determine the association between gut microbes and the weight of adolescents from previously unexplored regions such as Siberia, Russia.

Composition and Structure of Gut Microbiome in Adolescents with Obesity and Different Breastfeeding Duration

Gut microbiome of adolescents with obesity and different duration of breastfeeding was analyzed by metagenomic analysis of V3-V4 variable domains of the 16S rRNA gene. In subgroup with breastfeeding duration <3 months, intrapopulation structure of gut microbiome by alpha diversity indices was similar in adolescents with obesity and normal body weight. The decrease in phylotype abundance in the structure of communities was associated only with obesity, while dysbiotic state persisted in both lean and overweight adolescents, which confirmed the effect of breastfeeding duration on stability of gut microbiome.

Metagenomic analysis of mycobacterial transrenal DNA in patients with HIV and tuberculosis coinfection

The existence of "transrenal" DNA (tr-DNA), i.e. cell-free DNA that has distributed through the renal barrier to the urine, was first shown from a pathogen in 2000 (Botezatu et al., 2000). However, a targeted search for tr-DNA from Mycobacterium tuberculosis (MBT) started relatively recently (Cannas et al., 2008; Green et al., 2009). While other MBT cellular components found in the urine, e.g. lipoarabinomannan, have been used as an enhanced diagnostic tool, tr-DNA has the potential for strain specific identification or a more persistent biomarker during treatment of active disease. We therefore sought to identify by high-throughput next generation sequencing (NGS) MBT genome fragments in the urine of people with human immunodeficiency virus and tuberculosis (HIV-TB) co-infection living in a co-epidemic setting, and to evaluate whether these DNA targets are suitable for the development a quantitative TaqMan polymerase chain reaction with real-time detection (rt-PCR). Selection and mapping to the reference MBT genome of strain H37Rv (NC_000962) revealed 158 fragments of mycobacterial DNA with length from 19 to 44 base pairs (bp) repeated in different DNA samples. Five targets were chosen for design of rt-PCR primers and probes. Comparative analysis of the newly developed tests that were based on the results of NGS did not reveal a significant increase in sensitivity and specificity relative to the previous empirically designed targets. Howver, highly reproducible NGS reads of mycobacterial tr-DNA were obtained. rt-PCR test development suitable for more practical clinical use was likely limited by the small size of the secreted DNA fragments. It is necessary to develop further molecular approaches for the detection of mycobacterial tr-DNA or rely on NGS techniques with inherent bioinformatics requirements.

The Phylogenetic Position of Spironucleus sp. (Diplomonadida: Hexamitidae) from the Intestine of Chinese Sleeper Perccottus glenii Dybowski, 1877 (Actinopterygii: Odontobutidae)

INTRODUCTION

The Chinese (Amur) sleeper (Perccottus glenii Dybowski, 1877) (Actinopterygii: Odontobutidae) is a freshwater fish species with high invasive potential. Diplomonads have been detected in the intestines of Chinese sleepers using light microscopy.

AIM

The aim of this study was to identify the diplomonads in Chinese sleepers using molecular-genetic methods.

MATERIALS AND METHODS

The fish used in this analysis were caught in the following bodies of water in Russia between 2014 and 2016: Lake Dolgoe, the floodplain of the Ingoda River (Amur River basin), the Tsna River (the Oka River basin), and the littoral of the Kotlin Island (Gulf of Finland). Partial sequences of small subunit rRNA genes were obtained for the intestinal diplomonads of Chinese sleeper.

RESULTS

The analysis of all sequenced samples revealed the presence of Spironucleus salmonis Moore, 1922; other Spironucleus species were not found in the sampled fish. With 82% probability, the sampled sequences of diplomonads from Chinese sleeper formed a separate cluster in the clade of S. salmonis on the phylogenetic tree.

CONCLUSION

This is the first record of S. salmonis in fish in the family Odontobutidae.

Diversity and shifts of the bacterial community associated with Baikal sponge mass mortalities

The disease of freshwater sponges was first discovered in 2011, when pink samples were found in the Central Basin of Lake Baikal. Subsequently, the visible signs of the disease have changed, and now sponges appear with various symptoms of damage to the body, such as discoloration, tissue necrosis, the formation of brown patches and dirty-purple biofilms on some branches. These signs of the disease are accompanied by the mass death of sponges. We identified differences in microbiomes by sequencing 16S rRNA genes and found changes in the consortium of microorganisms of freshwater Baikal sponges. We found that the observed imbalance in the studied microbial communities of diseased sponges is caused by several different conditionally pathogenic microorganisms that increase their negative effect by acting together and in concert, which leads to the death of photosynthetic microalgae and sponges. Sponges are an important component of coastal communities, and the massive loss of sponges can obviously affect the structure of benthic communities and the purity of water.

The signs of adaptive mutations identified in the chloroplast genome of the algae endosymbiont of Baikal sponge

BACKGROUND

Monitoring and investigating the ecosystem of the great lakes provide a thorough background when forecasting the ecosystem dynamics at a greater scale. Nowadays, changes in the Baikal lake biota require a deeper investigation of their molecular mechanisms. Understanding these mechanisms is especially important, as the endemic Baikal sponge disease may cause a degradation of the littoral ecosystem of the lake.

METHODS

The chloroplast genome fragment for the algae endosymbiont of the Baikal sponge was assembled from metagenomic sequencing data. The distributions of the polymorphic sites were obtained separately for the genome fragments from healthy, diseased and dead sponge tissues.

RESULTS

The distribution of polymorphic sites allows for the detection of the signs of extensive mutations in the chloroplasts isolated from the diseased sponge tissues. Additionally, the comparative analysis of chloroplast genome sequences suggests that the symbiotic algae from Baikal sponge is close to the Choricystis genus of unicellular algae.

CONCLUSIONS

Mutations observed in the chloroplast genome could be interpreted as signs of rapid adaptation processes in the symbiotic algae. The development of sponge disease is still expanding in Baikal, but an optimistic prognoses regarding a development of the disease is nevertheless considered.

[Taxonomic Composition of Lake Baikal Bacterioneuston Communities]

The taxonomic composition of microbial communities of Lake Baikal surface microlayer was studied by pyrosequencing of the 16S rDNA amplicons. Statistically reliable differences were found between bacterioneuston of the shallow and deep-water stations. The shallow station community was characterized by higher diversity than the deep-water one. While bacterioneuston communities were shown to be less diverse than the water column communities, their diversity was comparable to that of other biofilm associations. Microbial communities of Lake Baikal surface microlayer were shown to be similar to those of the water column in the composition of predominant phyla, while differing considerably at the genus level. Bacterioneuston of Lake Baikal was comparable to microbial communities of the surface microlayer of other freshwater basins, although it was characterized by high abundance of the Alphaproteobacteria and Verrucomicrobia. High abundance of photoheterotrophs compared to the water column communities of other freshwater basins was another distinctive feature of Lake Baikal bacterioneuston. Our results showed the Lake Baikal surface microlayer to be a specific microbial community with low species diversity and relatively high abundance of photoheterotrophic microorganisms.

[The structure of opportunistic microbiota of nasopharynx and vaginal tract in women with reproduction disorders and chronic endometritis.]

The study was carried out to investigate microbiocenosis of nasopharynx and vaginal tract in women with reproductive disorders and chronic endometritis. The females were separated on two groups. The first group included females with morphologically verified chronic endometritis (n=32). The second group included females without chronic endometritis (n=32). The chronic tonsillitis was established in 21 out of 65 females from first group and in comparison group only in 9 females. In the analyzed biotypes resemblance of main infection agents (staphylococcus,enterococсus, colibacillus) was established. In nasopharynx biotope normocenosis was established in first and second groups in 33.3% and 45% of cases correspondingly. The first degree of dysbiosis was determined in both groups with equal rate (55,5%), second degree of dysbiosis was established only in women with chronic endometritis and chronic tonsillitis (11.1%).

Phylogenetic and Functional Prokaryotic Diversity in the Hoito-Gol Mesothermal Mineral Spring (Eastern Savan Mountains. Buryat Renuhlie)

High-throughput sequencing was used for comparative analysis of microbial communities of the water and mat from the Hoito-Gol mesothermal mineral sulfide spring (Eastern Sayan Mountains, Buryat Republic). Activity of microbial communities was determined. While both spring biotopes were dominated by members of three bacterial phyla, Proteobacteria, Bacteroidetes, and Firmicutes, they differed drastically in the composition of predominant phylotypes (at the genus level). In the water, the organisms wide spread in aquatic'environments were predominant, mostly aerobic chemoorganotrophs of the generaAcinetobacter, Pe- dobacter, and Flavobacterium. In the microbial mat,;the organisms actively involved in the sulfur cycle predominated, including sulfur-reducing bacteria Sulfurospirillum, sulfate-reducing deltaproteobacteria, sulfur- oxidizing chemoautotrophic bacteria, anoxygenic phototrophic bacteria of,the phyla Chloroflexi and Chloro- bi, as well as purple bacteria belonging to the Q-, P--, and y-Proteobacteria. Microbial mats of the spring exhibited higher phylogenetic diversity compared to high-temperature mats containing photosynthetic microorganisms.

[Diversity and Physiological and Biochemical Properties of Heterotrophic Bacteria. Isolated from Lake Baikal Neuston.]

For heterotrophic microorganisms (44 strains) isolated-from the surface film of Lake Baikal, iden- tification was carried out and their. physiological and biochemical characteristics were determined. Com- pared to the water column, diversity of cultured heterotrophs was low, indicating formation of stable micro- bial communities at the air-water interphase interface. Heterotrophic bacteria isolated from the surface mi- crolayer exhibited the enzymatic activity comparable to that for strains form other biofilm associations. Deinococcusfi6us strain NA202 'vas the most active component of the community, capable of utilization of the broadest spectrum of mono- and disaccharides,'sugars, and amino acids. This strain possessed the highest diversity of extracellular enzymes and was the most resistant to UV radiation. The physiological and bio- chemical properties of this strain may-be responsible for its adaptation to survival in extreme conditions of the surface microlayer. Our results improve our understanding of occurrence of UV-resistant strains in freshwater ecosystems.

Genetic diversity of Diplomonadida in fish of the genus Coregonus from Southeastern Siberia

Diplomonadida are primitive flagellate protozoa, among which both commensals and pathogens have been recorded. To date, members of the genera Hexamita and Spironucleus have been reported in the digestive system of fish in the Baikal region. We determined the genetic diversity of Diplomonadida in fish of the genus Coregonus from south-eastern Siberia using molecular-genetic methods. Fish for analysis were caught in Lake Baikal and in the Barguzin, Nepa, Chechuy, and Kirenga rivers from 2010 to 2013. Gall bladders, hindguts and foreguts of 120 specimens of Coregonus migratorius representing three morpho-ecological groups, 25 specimens of Coregonus lavaretus baicalensis, 25 specimens of Coregonus tugun and 30 specimens of Coregonus lavaretus pidschian were analysed via amplification with primers specifically designed for eukaryotes. Amplicons positive for Diplomonadida were sequenced. A phylogenetic analysis revealed that diplomonad flagellates of whitefish from Southeastern Siberia belong to Spironucleus barkhanus. Positive Diplomonadida DNA samples were analysed with primers designed in the present study for the amplification of small subunits of ribosomal DNA fragments of S. barkhanus (about 1,430 bp) and sequenced. Phylogenetic analysis revealed inside the clade of S. barkhanus besides the cosmopolitan genotype from European salmon that was detected earlier in Baikalian grayling, a new genotype unique to the fish of the genus Coregonus from Lake Baikal.

[Study of the Microbiome of the Intestine of the Comephorus dybowski Korotneff, 1904]

Data on metagenomic analysis of the microbial community of the intestine of the Comephorus dybowski are presented for the first time. It was established that the bacterial community is characterized by a significant species diversity. In its composition 301 phylotypes (OTU) belonging to 23 phyla (out of which six are candidate, including the Thermobaculum, Gracilibacteria, Candidatus Saccharibacteria, TM6, Latescibacteria, and Parcubacteria) were detected. It was demonstrated that species richness estimated by means of the non-parametric ACE and Chao1 criteria was 568 and 504, respectively; and the species diversity by the Shannon index was 4.05. The analysis ofunique peculiarities of the C. dybowski ecology and biology allows us to explain some of the data obtained on the intestinal microbiome of this specie.