In the laboratories of the College of Medical Technologies / The Islamic University of  Najaf, the biosynthetic zinc nanoparticles were synthesized by Lactobacillus bacteria . The structural and morphological properties of Zinc Oxide Nanoparticles  were determined by Atomic force microscope and  X–ray diffraction analysis ,  (hexagonal phase ) shows that the synthesized nanoparticles were crystalline and pure in nature. The peaks at 2θ = 38.1, 44.18, 64.45, 77.12 & 81.03 were respection lines of spherical Zinc Oxide Nanoparticles  respectively. Then, maximum diameter measured for particles is 8 .4278 nm which determined by applying the Scherrer equation. After that, the samples of pathogenic bacteria (Staphylococcus aureus , Staphylococcus Epidermidis) diagnostic by Vitek2 compact system  resistant to commercial antibiotics were collected and the antibacterial activity of these nanoparticles was tested. The results of inhibiting the growth of pathogenic bacteria were good.Then the ZnONps were combined with a polymeric compound (Poly-β hydroxybutyrate  ) to improve the properties of the nanocomposite as an antimicrobial, as the combined compound)ZnONPs/PHB) gave great inhibition results compared to the nanocomposite alone(ZnONPs).