The origin of fecal floatation phenomenon remains poorly understood. Following our serendipitous discovery of differences in buoyancy of feces from germ-free and conventional mice, we characterized microbial and physical properties of feces from germ-free and gut-colonized (conventional and conventionalized) mice. The gut-colonization associated differences were assessed in feces using DNA, bacterial-PCR, scanning electron microscopy, FACS, thermogravimetry and pycnometry. Based on the differences in buoyancy of feces, we developed levô in fimo test (LIFT) to distinguish sinking feces (sinkers) of germ-free mice from floating feces (floaters) of gut-colonized mice. By simultaneous tracking of microbiota densities and gut colonization kinetics in fecal transplanted mice, we provide first direct evidence of causal relationship between gut microbial colonization and fecal floatation. Rare discordance in LIFT and microbiota density indicated that enrichment of gasogenic gut colonizers may be necessary for fecal floatation. Finally, fecal metagenomics analysis of ‘floaters’ from conventional and syngeneic fecal transplanted mice identified colonization of > 10 gasogenic bacterial species including highly prevalent B. ovatus, an anaerobic commensal bacteria linked with flatulence and intestinal bowel diseases. The findings reported here will improve our understanding of food microbial biotransformation and gut microbial regulators of fecal floatation in human health and disease.
0.009) H 2 baseline (14.1 6 7.1 ppm (mean 6 SD)) than controls (6.8 6 3.9 ppm). The IBS group baseline CH 4 (12.1 1 11.5 ppm) was 36% higher than the healthy controls (7.8 6 7.8 ppm) but didn't reach statistical significance (p 5 0.3) (Table ) Conclusion: Given the connection between diverse gut microflora and health, finding mechanisms to influence this environment is favorable. Prebiotic fibers, like 2'-FL, have the potential to enrich this microenvironment through microbial fermentation. However, in order to gain such a health benefit, the prebiotic must be metabolized by the host's gut microflora. Our data demonstrate the individualized nature of host-microbiome fermentation response across subjects and support the use of a more personalized approach. Daily breath analysis has the potential to identify microbial responders, as well as being used to help optimize dosing and tolerance over time.
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