Isolation and characterization of BpL1, a broad acting lytic bacteriophage against Brucella

We have isolated a new broad acting lytic brucellaphage (BpL1) from the sewage of a dairy farm. The phage lysed all the 12 Brucella abortus field isolates, B. abortus strain 99 and Brucella melitensis but did not lyse any of the heterologous species tested viz. Staphylococcus aureus, Pasteurella multocida, Escherichia coli, and Salmonella species. Streaking the plaques on Brucella lawn gave clear zones along the streak lines. The plaques were circular with a diameter of 0.5- 3.0 mm. At a concentration of 10-4 the phage count was 4.5 x 106 plaques per ml. It was a tailed phage with icosahedral head (62.2 nm in diameter and 73.71 nm in length), and the head to tail length was 229.21 nm. The phage belonged to the order Caudovirales and family Siphoviridae. It was inactivated within one hour at 55{degrees}C and within 4 hours at -20{degrees}C. Treatment at pH 2 for 4 hours and at pH 4 for 12 hours inactivated it. It was inactivated after 4 hours exposure to sunlight, and within 4 minutes by UV light. Chloroform and Sodium Dodecyl Sulfate inactivated it within 15 minutes. Lysozyme inactivated it within 1 hour whereas RNase treatment did not affect its activity.