ABSTRACT
The gram-positive, mesophilic and non-motile coccus Streptococcus gordonii is an important causativeagent of infective endocarditis (IE). This pioneer species of dental plaque also causes bacteraemiain immune-supressed patients. In this study, we analysed the genome of a representative strain,Streptococcus gordonii SK12 that was originally isolated from the oral cavity. To gain a better understandingof the biology, virulence and phylogeny, of this potentially pathogenic organism, high-throughput IlluminaHiSeq technology and different bioinformatics approaches were performed. Genome assembly of SK12was performed using CLC Genomic Workbench 5.1.5 while RAST annotation revealed the key genomicfeatures. The assembled draft genome of Streptococcus gordonii SK12 consists of 27 contigs, with agenome size of 2,145,851 bp and a G+C content of 40.63%. Phylogenetic inferences have confirmedthat SK12 is closely related to the widely studied strain Streptococcus gordonii Challis. Interestingly, wepredicted 118 potential virulence genes in SK12 genome which may contribute to bacterial pathogenicityin infective endocarditis. We also discovered an intact prophage which might be recently integratedinto the SK12 genome. Examination of genes present in genomic islands revealed that this oral strainmight has potential to acquire new phenotypes/traits including strong defence system, bacitracinresistance and collateral detergent sensitivity. This detailed analysis of S. gordonii SK12 further improvesour understanding of the genetic make-up of S. gordonii as a whole and may help to elucidate howthis species is able to transition between living as an oral commensal and potentially causing the lifethreateningcondition infective endocarditis.