Objective      To isolate and identify a new mycobacteriophage Chy2

and to explore its biological characteristics.       Methods      The new mycobacteriophage was isolated and purified from soil by single-plate method. The phage was induced by ultraviolet ray (UV) to identify its lytic or lysogenic capacity. Chy2

D29 and TM4 were compared by the plaque size

particle morphology and restriction enzyme analysis. Chy2 was amplified by double-layer agar plate method in different multiplicity of infection (MOI) to find

the optimal MOI. One-step growth experiment was performed to find the latent period

burst period and burst size of Chy2. The host range of Chy2 was examined by single-spot examination. The ability of Chy2 to crack Mycobacterium smegmatis mc

2

155 at different pH values was examined.       Results      A new mycobacteriophage was successfully isolated and purified

which was named as Chy2. The plaques of Chy2 were round and transparent

and their sizes were about 3 mm in diameter. Plaques did not appear with the host bacteria induced by UV. Chy2 has an oval head and a long tail. The size of Chy2 genome was about 49 kb

which was different from that of D29 or TM4

and its genome can be digested by the restriction endonucleases of EcoRⅠ

HindⅢ

BamHⅠ and XbaⅠ. The optimal MOI and the highest titer of Chy2 were 9.58×10

-5

and 7.2×10

10

PFU/ml

respectively. The one-step growth cycle of Chy2 was 270 min

with the latent period 210 min

the burst period 60 min and the burst size 23. Chy2 could crack Mycobacterium smegmatis mc

2

155

Mycobacterium tuberculosis H

37

Rv and a majority of clinical drug-resistant bacterial strains. Chy2 could crack Mycobacterium smegmatis mc

2

155 in solid medium at pH 5.0 and pH 7.4.        Conclusion      Chy2 belongs to Siphoviridae family and has genome of double-stranded DNA. Chy2 has a broad host range and

therefore

has a potential role in anti-tuberculosis treatment.