Psychrobacter immobilis isolated from foods: characteristics and identification

Abstract

A total of 15 strains of Psychrobacter immobilis isolated from animal sources, e.g. cheese, fish and poultry, were tested. A commercial diagnostic kit NEFERMtest 24, conventional tests and determination of fatty acids were used for identification. By using the results of NEFERMtest 24 and numerical identification system TNW version 6.0 the identification was successful on the species level (46.7%) while the correct species identification by using conventional tests increased up to 86.7%. All 9 saccharolytic strains including 7 Czech isolates were identified in most cases on an excellent or very good level by both methods based on biochemical reactions. On the other hand, the identification of 6 asaccharolytic strains was unsuccessful especially by NEFERMtest 24. While 4 asaccharolytic strains were identified correctly on the basis of conventional tests on species or genus level, incorrect identification on species level, for example Ralstonia paucula, Comamonas terrigena, Oligella ureolytica, Moraxella lincolnii andPsychrobacter phenylpyruvicus, was found by using NEFERMtest 24. Determination of fatty acid composition by MIDI System confirmed the species identification of 9 out of the 10 tested strains of P. immobilis and 1 tested strain of Psychrobacter sp.