The Interaction Of Different Phenotype Staphylococcus Epidermidis And The Influence Of Luxs Gene On Biofilm Formation

OBJECTIVEWe investigate the interaction mechanisms among the different phenotypes ofStaphylococcus epidermidis and the role of LuxS in the process of biofilm formation.METHODS(1)SE ATCC35984with the ability of biofilm formation and SE ATCC12228without this ability were cultured respectively with TSB medium, supernatant1andsupematant2, and polysaccharide intercellular adhesion was qualitatively detected bythe Congo red plates.(2) SE ATCC35984with the ability of biofilm formation wascultured respectively with supernatant2and supematant3, and then cultured in96wellplate.We abserved bacterial adhesions in96well plates.(3) We abserved bacterialadhesion in96well plates after that SE ATCC35984was cultured in medium1thatsupematant2used double dilution method by TSB and SE ATCC12228was cultured inmedium2that supematant1used double dilution method by TSB.(4)We collected SEATCC12228after cultured respectively with TSB and supernatant1and SEATCC35984after cultured respectively with TSB and supernatant2,and the expressionof LuxS in the strains were detected by semi-quantitative PCR method.RESULTS(1) Staphylococcus were growed in Congo red medium In the control groups A1,SE ATCC35984bacterial colonies was black, shiny, drying colony in Congo red plates,while the color of bacterial colonies in the experimental groups A2was black wine red. The color of bacterial colonies in the B experimental groups was black wine red whilethe color of bacterial colonies was red and smooth in the control groups B1.(2) Thestrains of control group A1could formate thick and dense biofilm, while the strains ofexperimental group A2formated a thin and sparse biofilm.. The differences amongthese groups were significant(P<0.05).The strains of B1in control groups could notform biofilm, and the strains of B2in experimental groups could obviously formbiofilm after cultured with the supernatant1, the differences between these groups weresignificant(P<0.05). In control group C, TSB medium, supernatant1and supematant2,could not formate biofilm.(3) When the medium1diluted to256times by TSB, TheOD of SE ATCC35984biofilm was similar compared with cultured in TSB. The strainsof SE ATCC12228could not produce biological membrane when the medium1dilutedto16times.(4) LuxS were expressed in the4groups of strains, but cultured by SEATCC35984supematant, the ability of SE ATCC12228biofilm formation was increased,and the expression of LuxS in the strains was reduced. Similarly, the biofilm formationability was reduced and the expression of LuxS was increased in the strain of SEATCC35984cultured by ATCC12228supernatant. The differences among these groupswere significant (P<0.05).CONCLUSIONS1. There may be an interactional phenomenon among the different phenotypes ofStaphylococcus epidermidis.2. LuxS gene may play a regulatory role in the process of biofilm formation ofStaphylococcus epidermidis3. The AI-2signal may play the role of regulation when the concentration reaches acertain range.4. The supematant of Pseudomonas aeruginosa may have something to decompose AI-2signal molecules.