Table 4.

Antibacterial activities of green-synthesized cobalt and cobalt oxide NPs

Biological entity	NPs	Test microorganisms	Method	References
Celosia argentea	Cobalt	Bacillus subtilis and Escherichia coli	Disk diffusion	[32]
Ziziphora clinopodioides Lam	Cobalt	Salmonella typhimurium, E. coli, Streptococcus pneumonia, Pseudomonas aeruginosa, Staphylococcus aureus, and B. subtilis	Disk diffusion	[37]
Raphanus sativus var. longipinnatus	Cobalt	Pseudomonas putida and Klebsiella pneumonia	Disk diffusion	[39]
Hibiscus cannabinus	Cobalt	B. subtilis and E. coli	Agar well diffusion	[41]
Vitis vinifera	Cobalt oxide	P. aeruginosa, E. coli, S. aureus, and B. subtilis	Disk diffusion	[46]
Calotropis procera	Cobalt oxide	E. coli, Pseudomonas sp., Alcaligenes sp., and Enterococcus sp.	Disc diffusion	[47]
Moringa oleifera	Cobalt	E. coli and S. aureus	Agar well diffusion	[51]
Sechium edule	Bimetallic cobalt	B. subtilis and E. coli	Disk diffusion	[60]
Populus ciliata	Cobalt oxide	Bacillus licheniformis, B. subtilis, K. pneumonia, and E. coli	Well diffusion	[63]
Sageretia thea	Cobalt oxide	P. aeruginosa, E. coli, K. pneumonia, Staphylococcus epidermis, S. aureus, and B. subtilis	Disc diffusion	[65]
Chromolaena odorata	Cobalt	E. coli, K. pneumonia, S. aureus, and Streptococcus pyogenes	Agar well diffusion	[69]
Catharanthus roseus/Periwinkle	Cobalt	B. subtilis and E. coli	Disc diffusion	[70]
Sesbania sesban	Cobalt oxide	S. aureus	Disk diffusion	[71]
Proteus mirabilis	Cobalt	P. aeruginosa, Salmonella typhi, E. coli, Clostridium perfringens, Enterococcus faecalis, Bacillus cereus, and S. aureus	Well diffusion	[76]
Aspergillus brasiliensis	Cobalt oxide	B. subtilis, S. aureus, P. aeruginosa, and E. coli	Agar well diffusion	[83]

Abbreviation: NPs, nanoparticles.