Abstract

To determine the most probable number (MPN) of Coliform and to identify the Coliform bacteria present in the raw milk in the three geographical areas of Khartoum state. Six hundred and forty four raw milk samples were collected during the period between April 2008 to February 2009. The Coliformlimits in the raw milk accepted internationally are less than 100 cell/ml. About 51.3% of the samples from the milk available for direct consumption in Khartoum state [vendor + (shops) market milk] satisfy this limit. In winter and summer the percentages of milk samples which satisfy this limit were 70.4 and 51.3%, respectively. Vendor milk is more contaminated with Coliform bacteria compared to milk from the shops; only 47.8% were in the acceptable limits during winter and 43.7% summer. The difference between winter and summer counts, and the differences between individual, bulk, vendor and shops were statistically significant, at p(0.05). In this study 60.1% of all the raw milk samples in the state were of counts between 0 to <100 cell/ml, but in winter the percentage (76.9%) was higher than summer (53.6%). Statistically there was a significant difference between the two seasons in the state, but the differences between these three areas were statistically insignificant. The majority of theColiform isolates from the raw milk consumed in Khartoum state were Escherichia coli 32%, Enterobacter species 29.2%, Klebsiella species 19.4%, Serratia species 11.1% and Citrobacter 1.0%, in addition to some Enterobacteriaceae.

Key words: Coliform, Sudan, count, isolation, most probable number (MPN).