User:Vinodgupta299

Pan-genome:The concept of the pan-genome analysis though traditionally applied to delineate the complete repertoire of genes in different strains of a single species has recently been extended to represent the total gene complements in any pre-defined group of microorganisms. The pan-genome includes the "core genome" containing genes present in all genomes of a pre-defined group, a "dispensable genome" containing genes present in two or more genomes, and finally "unique genes" specific to single genome.

History: The term pan-genome was first coined a decade ago by Tettelin et al.

Types of Pan-genome: 1. Open Pan-genome: An open pan-genome indicates that a very large, undetermined number of additional genomes would be needed to identify all genes accessible to the species or genus. 2. Close Pan-genome: In case of close pan-genome, additional genomes sequenced do not provide additional new genes to expand the pan-genome — the entire gene repertoire has been characterized.

Application of Pan-genome: Pan-genome analyses provide a framework to determine the genomic diversity of the data set at hand, but also to predict, via extrapolation, how many additional whole genome sequences would be necessary to characterize the entire pan-genome or gene repertoire. Phylogenetic analysis also can be done using pan-genome which is based on whole genome content rather than one conserved gene (16s rRNA) or MLST genes.

The community composition of the human microbiome is known to vary at distinct anatomical niches. But little is known about the nature of variations, if any, at the genome/sub-genome levels of a specific microbial community across different niches. Habitat specific adaptation strategy can be explore by pan-genome analysis.