Monitoring of the succession of bacterial populations in infant faeces by PCR-denaturing gradient gel electrophoresis

Abstract

The aim of this study was to follow the evolution of faecal bacteria over the first 34 weeks of life using molecular methods in healthy infants, all of them initially breast-fed and then subjected to a similar succession of dietary changes. Faecal samples from six healthy, full-term, unrelated babies were subjected to PCR amplification with general primers for 16S bacterial rDNA. The PCR products were analysed by denaturing gradient gel electrophoresis (DGGE) to determine a pattern of predominant bacterial species in each sample. Detection of species of Bifidobacterium genus and Lactobacillus group was done using genus- or group-specific primers and sequencing DGGE bands. We detected an increment in the bacterial diversity in all infants, the more obvious changes being detected after introduction of a solid diet. Lactobacillus were detected from the third week and showed a frequent change of species. The presence of Bifidobacterium species was much more stable. Evolution of the microbiota in the six infants studied underwent significant changes until introduction of meat in the diet, but was unique for each infant despite the similarity of their feeding. © 2005 Taylor & Francis.