Objective        To construct a prokaryotic expression vector of bacteriophage AB3 endolysin (LysAB3)

and to investigate the antibacterial activity of LysAB3 against

Acinetobacter baumannii

.       Methods        LysAB3 gene was synthesized and inserted into vector pET28a(+) to construct recombinant expression plasmid pET28a-LysAB3. After expression in

E. coli

BL21 (DE3) and purification with Ni

2+

-NTA Sepharose

we determined the antibacterial activity

lysis spectrum

and optimal pH value and temperature of LysAB3. The degradation against peptidoglycans in the cell wall was analyzed. Scanning electron microscopy was used to observe the cell morphology of

Acinetobacter baumannii

exposing to LysAB3.       Results        The gel diffusion assay showed that LysAB3 had bactericidal effects against 40 strains of

Acinetobacter baumannii

and it was also able to degrade

Acinetobacter baumannii

peptidoglycan. Of LysAB3 effects

the optimal pH value is 7

and the optimal temperature is 25℃. LysAB3-treated

Acinetobacter baumannii

exhibited significant abnormalities

including deep roughening of cell surface

collapse of cell structure and cell debris.       Conclusion        Bacteriophage AB3 endolysin has significant antibacterial activity against

Acinetobacter baumannii

.