Assessment of Pseudomonas in Farm Bulk Milk

A survey was undertaken to determine the incidence of Pseudomonas spp, in farm bulkmilk supplies using a range of selective media. The proteolytic and lipolytic activities of thePseudomonas spp isolated during the survey was also investigated. In addition, the effectof the lactoperoxidase system on the growth of pseudomonads at refrigeration (7°C) andambient temperatures (30°C) was determined.Raw milk samples (150 in total) were collected from farm bulk tanks on government owneddairy farms situated around Mansoura city, El-Dakahlia province Egypt and storedovernight at 5°C before analysis. Of the 150 samples tested134 (89.3%) were found tocontain Pseudomonas spp. using Pseudomonas selective medium (PSM) compared to 148(98.7%) when Pseudomonas Aeromonas medium (PAM) was used. The difference inisolation rates between the media was found to be significant (p<0.001).In those samples in which Pseudomonas spp. were detected the pseudomonad count usingPSM ranged from 102 to 4.5x106 cfu/ml with a mean value of 4.5x106 cfu/ml. The highestfrequency distribution (7l.65%) lay within the range 104 to 106 cfu/ml (PSM). In the caseofPAM the corresponding count ranged from 102 to 7.7x106 cfu/ml with a mean value of2.2x105 cfu/ml. The highest frequency distribution (70.95%) lay between 105 and 107cfu/ml (PAM). A correlation coefficient r=0.62 (p>0.001) was determined when the countsobtained from both media (PSM and PAM) were compared.