Methods to study the physical locations of lactic acid bacteria and Escherichia coli O157:H7 in fermented sausages.

摘要

Escherichia coli O157:H7, an acid tolerant pathogenic organism, represents unique challenges to preventing food-borne illness because of its low infectious dose in combined with the disease severity. Although E. coli O157:H7 survived fermentation and drying processes, the locations where they survived are not known. Imprinting method revealed the approximate and bigger pictures of the survival sites. SEM, thought useful in some studies, was not appropriate to localize E. coli O157: H7 in fermented sausages. Gram-staining was an excellent method to localize LAB microcolonies in fermented sausages. LAB microcolonies were densely populated in muscle tissue but not in adipose tissue. E. coli O157:H7 was found in both adipose and muscle tissues which were treated with low pH solutions. Based on these findings, E. coli O157:H7 which survived the fermentation process is believed to be closely associated with adipose tissue where lactic acid concentration is thought to be low.