DETECTION OF PSEUDOMONAS-AERUGINOSA BY ME ANS OF A SYNTHETIC MEDIUM

A synthetic medium (Z-agar) was developed for the selective isolation of Pseudomonas aeruginosa bacteria from foodstuff. The synthetic mediu m -- as nitrogen and carbon source -- contains acetamide, of which, de composed for ammonia and acetic acid, P. aeruginosa produces itself th e necessary nutrient for its growing. The medium contains no inhibitor s. Selectivity of the medium was tested by the inoculation of pure cul tures of different microbes belonging to the groups of Pseudomonas, En terobacteriaceae, Bacillus, and Staphylococcus. Usefulness of the synt hetic medium was also tested by a nation-wide round test using two mil k samples containing 10(3)/ml (milk sample I) and 10(5)/ml (milk sampl e II) P. aeruginosa. It was found that the selectivity of the syntheti c medium was better than that of Cetrimide-agar (5) prescribed in the Hungarian standard. According to the results of the nation-wide round test, no significant differences were found between the results obtain ed by Cetrimide-agar and Z-agar in case of the milk sample containing 10(5)/ml P. aeruginosa (Fig. 1). However, in case of the milk sample c ontaining 10(3)/ml of P. aeruginosa, a significant difference was foun d in favor of the Z-agar (Fig. 2). From the point of view of reproduci bility and comparativeness, the results were comparable in case of bot h media (Table). The new medium was patented (1). It is produced and c ommercialized by REANAL Fine Chemicals in Hungary.