Abstract: Based on the two initial media, LST from FDA and A3 from GB, three types grams positive bacteria inhibitors were added to detect the Coliform bacteria in the food. The result indicated the media with the three grams positive bacteria inhibitors were bad for the detection of Coliform bacteria. Secondly, 7 types of grams positive bacteria were added into the A3 media with E.coli. During the 210 mixed fermentation piles, 92.42% were the same as the comparison fermentation piles, while the false positive ratio and false negative ratio were 2.84%, 4.74%, respectively. The data and the T test analysis showed the influence of grams positive bacteria on Coliform bacteria detection was weak. Thirdly, 4 types of grams positive bacteria caused false positive results were added into the A3 media. It was evident that the grams positive bacteria in the 120 simple fermentation piles didn’t lead to positive results. The results of grams staining illustrated the dominant bacteria in the fermentation liquor of A3 media were grams negative. A3 was a kind of initial fermentation media which was good for Coliform bacteria detection and bad for the growth of grams positive bacteria. Consequently, One-step fermentation was a good method which could detect the Coliform bacteria accurately.

Key words:  , Coliform bacteria； detection； One-step fermentation；