In Vitro antibacterial activity of ZnO nanoparticles against Klebsiella oxytoca isolated from honeybee (Apis mellifera)

Abstract

Honeybees (Apis mellifera) are environmentally and economically important insects, although their colonies are infected with a number of bacterial pathogens, including Klebsiella oxytoca, a Gram-negative bacterium that belongs to the Enterobacteriaceae family, that may contribute to the decline in the health of honeybees. The aim of this study was to assess the antibacterial activity of zinc oxide nanoparticles (ZnO NPs) against K. oxytoca, which was isolated from honeybees, in vitro. Samples were collected from a number of beehives from different places in Al-Diwaniyah Governorate, Iraq. Isolates were diagnosed using culture and biochemical tests, in addition to a confirmation diagnosis by the VITEK® 2 Compact System and 16S rRNA gene amplification. The 96-well microtiter plate method was used to evaluate the effectiveness of various ZnO NP concentrations (0, 10, 100, and 500 μg/ml). The results showed that ZnO NPs have effective inhibition on K. oxytoca. The concentration of 500 µg/mL was the most effective, with significant variations at the P < 0.05 level. These results show that ZnO NPs could be a good choice instead of antimicrobials used to control diseases caused by bacteria in honeybees.