Development of Bifidobacterium spp. in infants: Age dependent patterns and correlating factors
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Bifidobacteria are a major microbial component of infant gut microbiota which is believed to promote health benefits for the host and stimulate the maturation of immune system. Despite the importance we know little about the natural development of bifidobacteria in the infant gut. To address this question, we analyzed mixed Bifidobacterium clpC gene sequences from IMPACT (Immunology and Microbiology in Prevention of Allergy among Children in Trondheim) stool samples of 83 infants and their mothers using the novel multivariate statistical MCR-ALS approach. We also developed a novel basecaller script in MATLAB® environment which simplifies the use of the MCR-ALS method so that manual decoding is no longer required. Faecal material was sampled during the first and the second part of pregnancy, at 3 days, 10 days, 4 months, 1 year and 2 years after birth. Five dominant Bifidobacterium species were identified and verified by cloning. Stool samples were predicted to be rich in B. adolescentis, B. bifidum, B. dentium, B. breve and B. longum species. The B. longum group consisted of B. longum longum irrespective of age, however B. longum infantis was mostly identified in four-month-old individuals indicating a potential infant-to-infant nature of its transmittance. Local Similarity Analysis revealed self-supportive correlations between Bifidobacterium, Lactobacillales, Clostridium, Proteobacteria and other bacterial groups. The amount of B. breve in infants correlated with the incidence of common cold infections during pregnancy. Development of all Bifidobacterium and B. longum groups had correlation to the occurrence of vaginal fungal infection during pregnancy. Elevated amounts of B. adolescentis in four-month-old infants correlated to high IgE levels and eczema symptoms, while levels of the B. longum group in infants – to eczema. In conclusion, new patterns in bifidobacterial development and interaction are described. We believe this new knowledge will be important for the future understanding of bifidobacteria in health and disease.
Mastergradsoppgave i næringsrettet bioteknologi, Avdeling for lærerutdanning og naturvitenskap, Høgskolen i Hedmark, 2011. Master of applied and commercial biotechnology.