Biological characteristics of 3 lytic bacteriophages from the same host Klebsiella sp. AC-11

The bacterial strain AC-11 was isolated from marine aquaculture pond of the Third Institute of Oceanography in Xiamen, China, and its 16SrDNA sequence demonstrated 99.78% similarity to Klebsiella pneumoniae subsp. pneumoniae. A total of 3 lytic phages KP1, KP2 and KP3 were isolated with this bacterial strain as the host using double-layer agar method. Phage KP2 was from the same aquaculture pond where the host strain was isolated, and the other two phages were from Yuan Dang Lake (marine water) in Xiamen, China. Morphology of both phages and host were observed under transmission electron microscope. The restriction patterns of nucleic acid of the phages were estimated by dsDNA restriction enzyme BglⅡand EcoRⅤ. All of the 3 phages belonged to family Siphoviridae, but with different genome fingerprint patterns. The physiological characteristics of the phages such as the optimal multiplicity of infection, the one-step growth curves and the sensitivity to temperature, pH, UV light, ether and chloroform were also tested. The results indicated that the phages had different biological characteristics and thus belonged to different strain types. This could contribute to the diversity of phages, the diagnosis and treatment of potential diseases caused by Klebsiella pneumoniae and typing of the relating Klebsiella bacteria.