Comparative Analysis of Genus Bifidobacterium: Insight into its Host Adaptation

Satti, Maria Altaf (2021) Comparative Analysis of Genus Bifidobacterium: Insight into its Host Adaptation, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Scienze e tecnologie agrarie, ambientali e alimentari, 36 Ciclo.
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Abstract

Bifidobacteria is amongst one of the health promoting bacteria. The role of this important probiotic genera can be elucidated by understanding its genome. Comparative analysis of the whole genus of these bacteria can reveal their adaptation to a diverse host range. This study comprises of four research projects. In the first study, a reference library for genus Bifidobacterium was prepared. The core genes in each genus were selected based on a newly proposed statistical definition of core genome. Comparative analysis of Bifidobacterium with another probiotic genus Lactobacillus revealed the metabolic characteristics of genus Bifidobacterium. The second study investigated the immunomodulatory role of a B. bifidum strain TMC3115. The analysis of TMC3115 provided insights into its extracellular structures which might have their role in host interaction and immunomodulation. The study highlighted the variability among these genomes just not on species level but also on strain level in terms of host interaction. The last two studies aim to inspect the relationship between bifidobacteria and its host diet. Bifidobacteria, are both host- and niche-specific. Such adaptation of bifidobacterial species is considered relevant to the intestinal microecosystem and hosts’ oligosaccharides. Many species should have co-evolved with their hosts, but the phylogeny of Bifidobacterium is dissimilar to that of host animals. The discrepancy could be linked to the niche-specific evolution due to hosts’ dietary carbohydrates. The distribution of carbohydrate-active enzymes, in particular glycoside hydrolases (GHs) that metabolize unique oligosaccharides was examined. When bifidobacterial species were classified by their distribution of GH genes, five groups arose according to their hosts’ feeding behaviour. The distribution of GH genes was only weakly associated with the phylogeny of the host animals or with genomic features such as genome size. Thus, the hosts’ dietary pattern is the key determinant of the distribution and evolution of GH genes.

Abstract
Tipologia del documento
Tesi di dottorato
Autore
Satti, Maria Altaf
Supervisore
Dottorato di ricerca
Ciclo
36
Coordinatore
Settore disciplinare
Settore concorsuale
Parole chiave
Comparative genomics, Glyocosyl hydrolases, Host adaptation
URN:NBN
Data di discussione
19 Luglio 2021
URI

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