Isolation and characterization of Staphylococcus aureus starvat ion4 nduced, stationary-phase mutants defective in survival or recovery

Abstract

SUMMARY: Ten Staphylococcus aureus mutants, defective in the starvation-induced stationary phase of growth were isolated from two independent Tn917-LTVI transposon insertion libraries and were designated suv as they had apparent-suryival defects. Seven of these mutants were defective under amino-acid-limiting conditions alone. Two mutants (suv-3 and suw-20) demonstrated lower plating efficiency when starved for glucose, phosphate or amino acids and one mutant (suv-11) had reduced plating efficiency after amino acid or glucose starvation. All of the mutants tested were as resistant to hydrogen peroxide assault as the parent, but six were more sensitive to low pH conditions. All the mutants were physically mapped on the 5. aureus chromosome using PFGE. Chromosomal DNA flanking the Tn917-LNI insertion sites was rescued by cloning into Escherichia coli. DNA sequence analysis resulted in theidentification of a number of transposon-disrupted ORFs encoding putative components such as superoxide dismutase (suv-I), haem A synthase (suv-3)# a component of the 505 response (suv-9) and hypoxanthine-guanine phosphoribosyltransferase (suv-20). The Tn917-LTVI insertion created lac2 transcriptional fusions for some of the stationary-phase loci. Expression analysis indicated that suv-4 was induced at mid-exponential phase, whereas suv-3 and suv-II were induced at the onset of stationary phase. The possible roles of these suv components in stationary-phase survival or recovery is discussed.