Protein Leakage Induced Marine Antibiofouling Activity of Biosynthesized Zinc Oxide Nanoparticles

Abstract

Marine biofouling cause huge economic losses in the aquaculture industries as well as in the marine installation. Biofilm formation is an initial stage of biofouling. Conventional antifoulants including biocides and heavy metal induce toxicity to the aquatic organisms. Marine microorganisms provide a wide range of non-toxic biologically active molecules that helps in synthesis of antimicrobial compounds. The present study was aimed to synthesize zinc oxide nanoparticles (ZnO NPs) using cell free supernatant of Bacillus paramycoides. UV–visible spectrum showed the characteristic surface plasmon resonance absorption band for ZnO NPs at 372 nm. X-ray diffraction shows planes of hexagonal wurtzite structure of ZnO NPs and narrow peaks confirm the crystalline nature of ZnO NPs. Field emission scanning electron microscopic image shows spherical shaped particles in the range of 35–90 nm. Biosynthesized ZnO NPs cause membrane damage in bacterial cells and subsequent protein leakage. ZnO NPs showed remarkable antimicrobial activity against four marine biofilm forming bacteria i.e., Aeromonas hydrophila, Halomonas aquamarina, Escherichia coli and Vibrio parahaemolyticus. Minimum inhibitory concentration value was observed as 10 μg ml−1 with all the bacterial strains. This study also highlights the rapid biosynthesis of ZnO NPs using cell free supernatant of B. paramycoides.