In antibacterial study, all the strains showed only moderate activity on calcium chloride and effective activity on calcium oxide compounds but the plant mediated CaO nanoparticles showed a maximum activity of more than 30% on E. coli, P. aeruginosa, K. pneumoniae and S. aureus followed by S. typhi, V. cholerae and S. dysenteriae. The antibacterial activity of the CaCl2, CaO and plant mediated CaO nanoparticles against the pathogens was depicted in Fig. 7, Fig. 8 and Fig. 9.