Modified EC medium designated as SMEC medium was devised for the determination of
Eseherichia coli from various kinds of food.
Successful results were obtained on using SMEC medium in differentiating
E. coli from coliform bacteria group.
The composition and making procedure of the SMEC medium were described as follows:
Bacto-tryptose 20g
Lactose 5g
Sodium chloride 5g
K
2HPO
4 2g
KH
2PO
4 6.325g
Sodium lauryl sulfate 0.25g
Bile salt No. 2 0.5g
Streptomycin (SM) 10mg (10μg/ml)
0.2% BCP 16ml (0.032g)
Distilled water 1000ml
Adjust to pH 6.2
Dispense 10ml of liquid medium in Durham fermentation tube, and sterilized by Koch's steam sterilizer at 100°C for 60min and incubate at 44.5±0.1°C for 24 hours.
SMEC medium produced gas may be considered to show a positive result for
E. coli.Among food-borne EC groups, positive strains by EC test were utilized to test the detectability of the same strains by SMEC medium.
Results of the test were as follows: 100% in
E. coli I, 92.7% in
E. coli II, 27.2% in
Citrobacter freundii, 15.9% in
Klebsiella aerogenes and 23.5% in irregular type, respectively.
SMEC medium promoted the growth of
Escherichia coli type, but was significantly suppressive against other coliform group showing positive EC test.
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