Growth phenotype of the gpsA knockout strain. S. aureus strain PDJ28 (ΔgpsA) was grown in RN medium to an OD600 of 0.5 and the cells were harvested and washed to remove the glycerol supplement. The culture was split and resuspended in media either with or without 0.1% glycerol, and growth was followed as a function of time. The growth curve is representative example of the data obtained in duplicate experiments. The figure inset shows the multiplex PCR genotyping of the wild-type gpsA gene (528 bp) in strain RN4220 and the inactivated gpsA allele (394 bp) in strain PDJ28 as described under Methods.