Premium
The preparation of ampicillin dextrin agar for the enumeration of Aeromonas in water
Author(s) -
Havelaar A.H.,
Vonk M.
Publication year - 1988
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.1988.tb01271.x
Subject(s) - dextrin , agar , aeromonas , food science , chemistry , solubility , ampicillin , microbiology and biotechnology , bacteria , chromatography , biology , antibiotics , organic chemistry , starch , genetics
of ampicillin dextrin agar (ADA) has revealed problems in details of the preparation. The final pH of the medium varied substantially between different laboratories. Measuring temperature has a pronounced effect on the pH (0·7 units lower at 50°C than at 6°C). Addition of agar during medium preparation resulted in a fall in pH of 0·5 units. If poured plates were stored in the refrigerator, the pH was reduced by 0·1–0·4 units, in particular during the first day. Recovery of Aeromonas from pure cultures and naturally polluted samples was unaffected by variation in pH between 7·1 and 8·3 but colony differentiation was optimal at a higher pH. The use of ADA at a final pH of 7·8 ± 0·2 (at 25°C) is recommended. Different types of dextrin differed in respect of solubility, fermentability and colony differentiation. Optimal results were obtained with Difco 161 and Merck 3006.