[The NEFERM test in the identification of psychrotrophic bacteria isolated from milk and dairy products].

Sanitary and nutriti on quality of foods from animal sources, that means also of milk and dairy products, are significantly influenced by the presence of psychrotrophic bacteria, the lipolytic and proteolytic activity of which contributes to their nutritive and sensory changes. This applies particularly to psychrotrophic bacteria of the genus Pseudomonas, Shewanella, Alcaligenes and Flavobacterium (Muir and Phillips, 1984; Piton and Richard, 1985; Craven and Macauley, 1990). These bacteria cause raw and pasteurized milk to turn bitter and gelatinize, and/or technological problems during processing. In the present paper the possible use of NEFERM-test and numerical identification system TNW was verified for identification psychrotrophic, nonfermentative bacteria isolated from milk and dairy products. This research is a continuation of our preceding work (Urbanová and Pácová, 1995) dealing with identification of these bacteria in poultry. The test comprised 35 psychrotrophic, gram-negative, oxidase-positive nonfermentative bacteria isolated from raw milk (30 strains) and hard cheeses (5 strains). A commercial diagnostic kit NEFERM-test (Lachema a.s., Brno) and respective conventional methods were parallelly used for identification: the conventional methods were complemented by assays of oxidase (OXI) and beta-galactosidase (ONPG) using of commercial strips Lachema a.s. Additional tests were as follows: gelatin and Tween 80 hydrolysis, fluorescein production. The readings of yellow or orange pigment production were also applied. A numerical identification system TNW was used to process the results (Czech Collection of Microorganisms, Faculty of Science, Masaryk University, Brno). Correct identification of bacteria by means of commercial diagnostic kits depends particularly upon the high goodness of fit of the results obtained by conventional tests in relation to those obtained by commercial kits.(ABSTRACT TRUNCATED AT 250 WORDS)