Biofilm Formation and Analysis of Associated Genes Involved in Staphylococcus Isolates from Bovine Mastitis

Objective)The objective of the study was to investigate biofilm forming ability, distribution of biofilm-associated genes of the clinically isolated bovine mastitis Staphylococcus and the correlation of them. (Method)Staphylococcus biofilm formation was conducted using a silicone elastomer slices plate assay in 24-well plates, after rinsing planktonic bacteria away, the biofilm forming abilities of them were determined by silver staining qualitatively and by crystal violet staining quantitatively, and the structure of biofilm was observed by using scanning electron microscopy. bap, icaAD, icaBC, sar, agr, sigB, clfaA, clfaB, fnbpA and fnbpB were amplified by PCR.(Result) Formation of biofilm could be found macroscopically in 120 out of 137 strains by silver staining, and the biofilm formation rate was 87.6%. It showed that 5 strains didn't adhere to the surface of silica gel by crystal violet staining, while the rest 132 isolates did. bap was amplified in 57 isolates and icaAD and icaBC in 43 and 54 strains, respectively. sigB, sar and agr were amplified in 73, 49 and 38 isolates, and clfaA and clfaB in 76 and 50 strains, respectively. fnbpA was present in 52 strains and fnbpB in 26 isolates. (Conclusion) It reveals that bap, sigB, sar, icaAD and icaBC may be significant biofilm-associated genes, for these genes are present more in biofilm-positive strains than in biofilm-negative strains. The roles of agr, clfaA, clfaB, fnbpA, and fnbpB genes in biofilm development are unassured.