Effect of selected bacteria of the genus Pseudomonas on the quality of raw cow’s milk

Pseudomonas spp. are a psychrotrophic species associated with milk spoilage caused by its enzymatic activities. The aim of this study was to identify Pseudomonas spp. in raw cow’s milk and to investigate their associated enzymatic properties and the ability to produce pyoverdine pigment. For microbiological analysis, 2 ml of milk samples was taken in sterile sample boxes. Milk sampling was carried out according to the principles of STN EN ISO 707. By identification using the PCR method, of n=320 samples of raw cow milk a total of 73 isolates of Pseudomonas spp. were identified as P. putida (34.25%); P. fragi (13.70%); P. lundensis (9.59%) and Pseudomonas spp. (42.47%). Proteolytic activity determined at a temperature of 7°C was positive from n=20 selected isolates of Pseudomonas spp. (60%) isolates and a temperature of 25°C was positively detected (85%). Lipolytic activity determined at a temperature of 7°C was confirmed in 35% of isolates and a temperature of 25°C it was confirmed in 70% isolates. Pyoverdine pigment production was detected in 65% of isolates. The results reveal the enzymatic activity of Pseudomonas spp. present in raw cow’s milk and its spoilage potential at different temperatures in relation to pigment production.