The capsule and genetic background, rather than specific loci, strongly influence pneumococcal growth kinetics

Bacterial growth characteristics intrinsic to each strain can impact and influence gene expression, antibiotic susceptibility, and disease pathogenesis. However, little is known about specific genomic variations that influence these bacterial growth features. Here, we investigate the impact ofStreptococcus pneumoniaegenetics on itsin vitro growth features to shed light on genes that may be important targets in the development of vaccines and therapeutics. We use statistical models to estimate growth features and show that they varied significantly across capsular serotypes and lineages, strongly correlated with the phylogeny, and were highly heritable, highlighting a strong genetic basis. Despite this, genome-wide association studies revealed no specific genomic loci statistically associated with the growth features independently of the genetic background, including those in the capsular polysaccharide synthesis locus. Our findings show that the serotype and lineage, and possibly a combination of genomic loci, influence intrinsic pneumococcal growth kinetics, which may have implications on pneumococcal disease pathogenesis.