enterotype associates with diets supporting acidic faecal pH and production of propionic acid by microbiota.

Metabolism of dietary fibres by colon microbiota plays an important role for human health. Personal data from a nutrition study (57 subjects) were analysed to elucidate quantitative associations between the diet, faecal microbiome, organic acid concentrations and pH. Ratios of the predominant acids acetate, butyrate and propionate ranged from 1:0.67:0.27 to 1:0.17:0.36. Pectin-rich diets resulted in higher faecal acetate concentrations. Negative correlation between faecal pH and BSS was observed. Higher faecal pH and lower acid concentrations were related to the higher abundance of amino acid degrading , and , which are weak carbohydrate fermenting taxa Propionic acid correlated especially to high abundance of and low abundance of proteobacteria. The acetate to propionate ratio of the enterotype was about half of that of the enterotype. Based on the results we suggest the measurement of faecal pH and organic acid composition for research and diagnostic purposes.