Abundance and Diversity of Hydrogenotrophic Microorganisms in the Infant Gut before the Weaning Period Assessed by Denaturing Gradient Gel Electrophoresis and Quantitative PCR.

Delivery mode (natural vs. cesarean) and feeding type (breast vs. formula feeding) are \r\nrelevant factors for neonatal gut colonization. Biomolecular methods have shown that \r\nthe ecological structure of infant microbiota is more complex than previously proposed, \r\nsuggesting a relevant presence of unculturable bacteria. It has also been postulated \r\nthat among unculturable bacteria, hydrogenotrophic populations might play a key role \r\nin infant health. Sulfate-reducing bacteria (SRB), acetogens, and methanogenic archaea \r\nuse hydrogenotrophic pathways within the human colon. However, to date, few studies \r\nhave reported detection of hydrogenotrophic microorganisms in newborns, possibly \r\nbecause of limitations on available group-specific, culture-independent quantification \r\nprocedures. In the present work, we analyzed 16 fecal samples of healthy babies aged \r\n1–6 months by means of quantitative PCR (qPCR) targeting the 16S rRNA or metabolic \r\nfunctional genes and by denaturing gradient gel electrophoresis (DGGE). qPCR data \r\nshowed quantifiable levels of methanogens, SRB, and acetogens in all samples, indicat-\r\ning that the relative abundances of these microbial groups were not affected by delivery \r\nmode (natural vs. caesarian). DGGE revealed a high prevalence of the \r\nBlautia\r\n genus \r\nwithin the acetogenic bacteria despite strong interindividual variability. Our preliminary \r\nresults suggest that hydrogenotrophic microorganisms, which have been a neglected \r\ngroup to date, should be included in future ecological and metabolic studies evaluating \r\nthe infant intestinal microbiota.