Effects of Different Factors on Biofilm Formation by Staphylococcus epidermidis

Semi-quantitative assay was performed to examine the effects of factors in vitro and in vivo on biofilm formation by Staphylococcus epidermidis.The explored factors included medium,glucose and sucrose,pH value,sodium chloride,lactose,casein and Ca2+.The results showed that typtic soy broth(TSB)was the most preferable medium for both growth and biofilm formation of S.epidermidis in three tested media,and the optimum concentration of TSB was about 3%.Different concentrations of sodium chloride showed an obvious inhibition against S.epidermidis's biofilm formation at pH 7.When the pH value of medium was more than 7,the ability of biofilm formation by S.epidermidis was significantly reduced while the cell growth was normal.In simulative in vivo factors,a certain concentration of Ca2+(no less than 0.2%) and high concentration of lactose(no less than 8%) obviously inhibited biofilm formation by S.epidermidis,while the addition of casein to medium had no obvious effect on biofilm formation of S.epidermidis.