Background: The intestinal microbiota of Mongolians and its composition is of great interest of researchers, a few studies have did in this fields. Maybe Mongolian encompass a uniquely wide range of environmental conditions, ethno geographical cohorts and traditional nomadic lifestyles. Goal: We aimed to determine the amount of gut microbiota, including Lactobacillus and Bifidobacterium in the fecal samples of relative healthy Mongolian adults residing in various regions of Mongolia by conventional culture method and PCR. Material and Methods: The study was performed population based cross sectional study in healthy volunteers. In this study, 256 relative healthy Mongolian adults with no history of gastrointestinal associated diseases were enrolled between July 2018 and April 2019. Each participants was asked to complete a questionnaire containing 164 questions about demographics, physical activity, dietary habits. Fecal samples were collected for Lactobacillus and Bifidobacterium analysis using culture method and determination of genus of Bifidobacterium sрp and Lactobacillus spp by PCR. ResultsParticipants had a mean age of 38.9±12.8 years. The mean values of Lactobacillus by culture method were 5.9±1.28 and 6.24±0.94 log10 CFU/ml (4.67х106 , 4.66х106 CFU/ml), respectively. The abundance of Lactobacillus had a positive correlation with grams for fiber and amount of bifidobacterium ((r= 0.495, р<0.001, r=0.288, p<0.05), respectively). Significant difference were observed between groups of milk frequency per day for amounts of lactobacillus. In adult intestinal tracts, B.Bifidum was the most common taxon 31 (29%) followed by B. angulatum 14 (13.1%), B. adolescentis 10 (9.3%), B. catenulatum group 10 (9.3%), B. longum 9 (8.4%). B. lactis, B. breve, B. dentium and B. gallicum were subdominant species. Conclusion: The mean amount of Bifidobacterium and Lactobacillus of all participants were 6.24±0.94 and 5.9±1.28 log10 CFU/ml (4.66*106 , 4.67*106 CFU/ml) respectively. The Lactobacillus abundance of healthy adults was higher in region of Khangai, East and West of Mongolian than other regions. The composition of lactobacillus altered with ageing. Significant correlations were found between fiber, fats, potato and amount of Lactobacillus. Keywords: Bifidobacterium, Colony forming unit, Gut microbiota, Lactobacillus

Background: The first confirmed case of COVID-19 in Mongolia was reported on November 11, 2020. In response, the government imposed a nationwide lockdown, which significantly impacted the population’s mental health. Heightened levels of stress, anxiety, loneliness, and depression during the pandemic altered individuals’ psychological stability and behavior. Personality traits—defined as relatively stable patterns of emotion, cognition, and behavior—play a key role in stress responses and emotional regulation under pressure. Emerging evidence suggests that these psychological factors may influence the immune system’s responsiveness, including vaccine-induced antibody production. Aim: To evaluate the association between post-vaccination antibody responses and personality types following two doses of COVID-19 vaccines. Materials and Methods: A total of 738 participants who received two doses of COVID-19 vaccines (AstraZeneca ChAdOx1, n=29; Pfizer-BioNTech, n=119; Sinopharm BBIBP, n=590) and had no prior SARS-CoV-2 infection were enrolled. Serum samples were collected 21–28 days after the second dose, and SARS-CoV-2 RBD (S) IgG antibodies were measured using ELISA (Proteintech Inc., USA). Personality types were assessed using a 56-item temperament questionnaire developed by A. Belov, categorizing individuals into classical temperament types (choleric, phlegmatic, sanguine, melancholic). Logistic regression and ROC analysis were used to examine associations between personality types and antibody response. Results: The presence of an antibody response was significantly higher among individuals with a melancholic tempera ment, and significantly lower among those with a phlegmatic temperament. Furthermore, antibody titers were higher in participants with melancholic and sanguine temperaments and lower in those with a phlegmatic type. Conclusions 1. During the early period following the second dose of COVID-19 vaccination, the antibody response was higher in individuals with a pure melancholic temperament, while it was lower in those with a phlegmatic temperament. 2. After the second dose of the Sinopharm BBIBP COVID-19 vaccine, antibody titers were higher in individuals with pure melancholic and sanguine temperaments, and lower in those with a phlegmatic temperament.