Combination of dynamic turbidimetry and tube agglutination to identify procoagulant genes by transposon mutagenesis in Staphylococcus aureus

Abstract

Agglutinating function is responsible for an important pathogenic pattern in S.aureus. Although the mechanism of aggregation has been widely studied since S.aureus has been found, the agglutinating detailed process remains largely unknown. Here, we screened a transposon mutant library of Newman strain using tube agglutination and dynamic turbidmetry test and identified 8 genes whose insertion mutations lead to a decrease in plasma agglomerate ability. These partial candidate genes were further confirmed by gene knockout and gene complement as well as RT-PCR techniques. these insertion mutants, including NWMN_0166, NWMN_0674, NWMN_0756, NWMN_0952, NWMN_1282, NWMN_1228, NWMN_1345 and NWMN_1319, which mapped into coagulase, clumping factor A, oxidative phosphorylation, energy metabolism, protein synthesis and regulatory system, suggesting that these genes may play an important role in aggregating ability. The newly constructed knockout strains of coa, cydA and their complemented strains were also tested aggregating ability. The result of plasma agglutination was consistent between coa knockout strain and coa mutant strain, meanwhile, cydA complement strain didn’t restored its function. Further studies need to confirm these results. These findings provide novel insights into the mechanisms of aggregating ability and offer new targets for development of drugs in S.aureus.