title: The Geobacillus Pan-Genome: Implications for the Evolution of the Genus.
abstract: The genus Geobacillus is comprised of a diverse group of spore-forming Gram-positive thermophilic bacterial species and is well known for both its ecological diversity and as a source of novel thermostable enzymes. Although the mechanisms underlying the thermophilicity of the organism and the thermostability of its macromolecules are reasonably well understood, relatively little is known of the evolutionary mechanisms, which underlie the structural and functional properties of members of this genus. In this study, we have compared 29 Geobacillus genomes, with a specific focus on the elements, which comprise the conserved core and flexible genomes. Based on comparisons of conserved core and flexible genomes, we present evidence of habitat delineation with specific Geobacillus genomes linked to specific niches. Our analysis revealed that Geobacillus and Anoxybacillus share a high proportion of genes. Moreover, the results strongly suggest that horizontal gene transfer is a major factor deriving the evolution of Geobacillus from Bacillus, with genetic contributions from other phylogenetically distant taxa.
authors.affiliation: Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria Pretoria, South Africa.
authors.forename: Oliver K
authors.initials: OK
authors.lastname: Bezuidt
authors.affiliation: Department of Biochemistry, Centre for Bioinformatics and Computational Biology, University of Pretoria Pretoria, South Africa.
authors.forename: Rian
authors.initials: R
authors.lastname: Pierneef
authors.affiliation: Equipe Métabolites des Extrêmophiles, Laboratoire de Recherche Biotechnologie et Qualité des Aliments, Institut de la Nutrition de l'Alimentation et des Technologies Agro-Alimentaire, Université des Frères Mentouri Constantine, Algeria.
authors.forename: Amin M
authors.initials: AM
authors.lastname: Gomri
authors.affiliation: Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria Pretoria, South Africa.
authors.forename: Fiyin
authors.initials: F
authors.lastname: Adesioye
authors.affiliation: Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria Pretoria, South Africa.
authors.forename: Thulani P
authors.initials: TP
authors.lastname: Makhalanyane
authors.affiliation: Equipe Métabolites des Extrêmophiles, Laboratoire de Recherche Biotechnologie et Qualité des Aliments, Institut de la Nutrition de l'Alimentation et des Technologies Agro-Alimentaire, Université des Frères Mentouri Constantine, Algeria.
authors.forename: Karima
authors.initials: K
authors.lastname: Kharroub
authors.affiliation: Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria Pretoria, South Africa.
authors.forename: Don A
authors.initials: DA
authors.lastname: Cowan
keywords: Geobacillus; conserved core; flexible genomes; horizontal gene transfer; pan-genome; soft core