Relative Abundance of Lactobacilli in the Fecal Microbiome of Post-menopausal Women

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Introduction: Fecal microbiome composition may play an important role in the pathogenesis of gastrointestinal (GI) disorders (Gut 2015). Several epidemiological studies have shown increased incidence of irritable bowel syndrome (IBS) and recurrent Clostridium difficile infection (RCDI) in women compared to men. IBS is more prevalent in younger and RCDI in older women. Thus, we postulated that variations in the gut microbiome in women of different age groups may play a role in disease susceptibility. Currently, there are insufficient data on the effect of gender on the gut microbiome and its potential impact on disease predisposition toward certain GI disorders. The aim was to examine microbiome of healthy women of different age groups by performing genomic analysis and comparing them to healthy men. Methods: Fecal samples were collected from all study subjects. They were processed and analyzed using 16S rRNA gene amplicon sequencing. Microbiota compositions were studied using standard 16S rRNA analysis tools(CloVR-16S). Differences in relative bacterial abundance, phylogenetic distances, diversity and individual bacterial families of men and women were analyzed. Results: Fecal microbiota of 30 healthy women and 9 healthy men were analyzed. The weighted Unifrac analysis showed that there were significant differences in the phylogenetic distances of microbial communities in the fecal microbiome of women than to men (p < 0.05; Figure 1). At the family level, Actinomycetaceae and Coriobacteriaceae were significantly more abundant in women than to men (Figure 2). At the genus and species levels, several pathogenic bacteria like Streptococcus, Escherichia coli, Clostridium perfringens and Collinsella aerofaciens were more abundant in the fecal microbiome of women. Further subgroup analysis demonstrated that older women (>60 years, post-menopausal) had a higher abundance of Lactobacillaceae family (including genus Lactobacillus) than younger women ( < 40 years, pre-menopausal). However, the Shannon index was not different in the two groups.Figure 1Figure 2Conclusion: These data suggest marked differences in the fecal microbiome of women and men. Postmenopausal women appear to have a higher abundance of Lactobaccillaceae. Lactobaccillaceae are associated with increased lactic acid production, which may modulate the overall ecology and function of the colonic bacteria. These variations in fecal microbiome of women may be related to differences in diet, nutritional supplements, medications and gonadal hormones.