  Pan-genome analysis is a standard procedure to decipher genome heterogeneity
and diversification of bacterial species. Specie evolution is traced by
defining and comparing the core (conserved), accessory (dispensable) and unique
(strain-specific) gene pool with other strains of interest. Here, we present
pan-genome analysis of the genus Serratia, comprising of a dataset of 100
genomes. The isolates have clinical to environmental origin and consist of ten
different species from the genus, along with two subspecies of the
representative strain Serratia marcescens. Out of 19430 non-redundant coding
DNA sequences (CDS) from the dataset, 972 (5%) belonged to the core genome.
Majority of these genes were linked to metabolic function, followed by cellular
processes/signalling, information storage/processing while rest of them were
poorly characterized. 10,135 CDSs (52.16%) were associated with dispensible
genome while 8,321 CDSs (42.82%) were singletons or strain specific. The
Pan-genome orthologs indicated a positive correlation to the number of genomes
whereas negative correlation was obtained for core genome. Genomes were aligned
to obtain information about synteny, insertion/inversion, deletion and
duplications. This study provides insights into variation of Serratia species
and paves way for pan-genome analysis of other bacterial species at genus
level.
