Background and Aim:Toxicity to human body and emergence of bacterial resistance have increased the interest for inorganic disinfectants such as metal oxide nanoparticles (NPs) to locally kill bacteria or slow down their growth. Furthermore the birth of nanotechnology provided new insights into antibiolm research as these nanoparticles are highly reactive and effective in penetrating the biolm matrix. As luminescent Vibrios are serious pathogens for marine fish and invertebrates such as Penaeid shrimp, in this study the potential antibacterial and antibilfilm properties of ZnO NPs against three isolate of Luminescent Vibrios have been investigated. Methods:Isolation was performed on shrimp farm water samples using TCBS and SWC medium specific for luminescent Vibrio species. Isolates were identified using morphological, biochemical tests and also 16S rRNAgene sequencing analysis. ZnO NPs were chemically synthesized by solnothermal methods. After determination of MIC, for microtiter biofilm production assay, bacteria were cultured in TSB medium for 24 hours and then incubated with crystal violet dye for 30 minutes. Remaining Crystal violet dye of each well bound to the biofilm was solubilized with 96% ethanol and optical density at (OD)570nm was read with ELISA reader apparatus. Results:Morphological characteristics and 16S rRNA gene analysis showed that isolates had 99% similarity to V. harveyi. In addition results showed that MIC for ZnO nanofluid against each 3 isolates (VHGA, VHGB, and VHGC) was 100 g/ml. Microtiter biofilm production assay showed that different isolates have varies in production of biofilm and get impressed under the effects of certain ZnO NPs concentration. Biofilm production decreased about 30% for isolate VHGA, 14% for isolate VHGB and 20% for isolate VHGC in one fourth of MIC concentration for three isolates. Conclusion:ZnO NPs have enough potential to be used as antibacterial agent against luminescent Vibrio isolates. In addition these nanoparticles can decrease production of biofilms in isolates or interact with biofilm structure that may because of the NPs abilities to penetrate in this structure.

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