Study On Detection Methods Of Foodborne Pathogenic Bacteria Biofilm

Foodborne pathogenic bacteria (Salmonella AS 1.1552 and Staphylococcus aureus AS 1.89) were chosen for study in this paper. The formation and structure features of 1-7 d biofilms were analyzed qualitatively and quantitatively by the appropriate methods. Based on the plate-swabbing method, a new method that was used to detect biofilm in lab was presented. It was ultrasonic-plate method. At last, the rapid methods for detecting biofilm were studied primarily.After measuring the viable counts of 1-7 d Salmonella sp. and Staphylococcus aureus biofilms, it was found that the growth current of their viable counts were different. The viable counts of the former were raising during the first four days and amounted to 106 cfu/cm2 on the second day. But the viable counts of the latter hadn't remarkable change and amounted to 106 cfu/cm2 on the first day. At the same time, silver staining and scanning electronic microscope methods were used to analyze the biofilms in quality.The viable counts of 1-7 d Salmonella sp. and Staphylococcus aureus biofilms were measured by the plate-swabbing method and the ultrasonic-plate method and the number detected by the ultrasonic-plate method was higher than the plate-swabbing method. After analyzing the results by the software SPSS, the correlation value of the two methods were 0.966 to Salmonella sp. Biofilm and 0.948to Staphylococcus aureus biofilm.2, 4, 6, 8,10,12, 14 min ultrasonic treatment time were used to remove 1-7 d Salmonella sp. and Staphylococcus aureus biofilms. The result showed that the ultrasonic-plate method and the plate-swabbing method had a good correlation .The correlation value was 0.905 to the Salmonella sp.biofilm when ultrasonic treated 8 min and 0.93 to Staphylococcus aureus biofilm when ultrasonic treated 10 min.Fluorescein diacetate method using to detect biofilm was studied. Experimental tests have shown a good correlation between the absorbance of the solution at 490nm and bacteria concentrations and the correlation value was 0.9511.