Niche-Specific Genome Evolution in Gastrointestinal Probiotics

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Niche-Specific Genome Evolution in Gastrointestinal Probiotics

Journal Title: Biomedical Journal of Scientific & Technical Research (BJSTR) - Year 2017, Vol 1, Issue 3

Abstract

IProbiotics are defined as health-promoting microbes which confer health benefits upon the host. Lactobacillus is regarded as the most diverse probiotic genus which harbors over 200 species among which are many strains with proved functional probiotic characteristics [1-3]. The economic significance of probiotics have courage scientists to study the biochemistry, genomics, phylogeny and physiology of lactobacilli, exhaustively. The genomic data highlighted the probiotic capabilities as strain specific traits which may be a result of the niche-specialization of the genomes of these bacteria to certain ecological niches (in this case the gastrointestinal tract of various animals). Another interesting feature of this genus may be the association between the genome size and the environmental distribution of its species [4,5]. The proposal of a co-evolutionary relationship between these bacteria with their hosts originates from the fact that certain Lactobacillus species have the capability to colonize the gastrointestinal tract (GIT) of animals and even some lactobacilli show degrees of hostspecificity in this regard. This evolutionary trend has resulted in a considerable rate of reductive evolution which is mirrored in their small genomes [4-6].The main trend in the evolution of the genomes of lactobacilli is genome decay which resulted in the general metabolic simplification although there are also accumulative evidences on gene duplications and acquisition events. Such evolutionary event shave been detected in habitat specialist lactobacilli. For examples L. helveticus (cheese inhabitant), L. sakei (meat inhabitant), and L. gasseri (GIT inhabitant). High inter and intra-species variability observed in lactobacilli is also attributed to the evolutionary events and these traits are considered as lifestyle adaption regions in the genome of Lactobacilli species [7-8]. Accumulation of pseudo genes and insertion sequence (IS) elements and decreasing rate of G+C content are known as characteristic features of a reductive genome minimization. Such evolutionary events are shown to be linked to a passage through a development bottleneck. The host-specificity and eco-physiological adaptations of pathogenic or non-pathogenic microbial species to anew habitats are the result of a reductive evolution. This is a development field which is associated to lack of selection pressure during evolutionary conversion from free-living to a host-associated lifestyle [9].Genome minimization is a critical evolutionary approach which can drive the environmental adaptation of species. The cellular adaptation to the environmental parameters may not just depend on gene absence or presence, but is also dependent on the accumulation of specific adaptive variations of genes. Phylogenetic analyses can be highly helpful to study the potential role of such genome variations in niche-specialization [8].

Authors and Affiliations

Moslem Papizadeh, Mohammad Reza Pourshafie

Keywords

Biomedical Research Biomedres Open access publishers Peer reviewed journals Special issues Biomedres – ebook publishers Biomedres – video publishers Biomedical Journal of Scientific & Technical Research

EP ID EP570644
DOI 10.26717/BJSTR.2017.01.000279
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