Table 2.

Bacterial-mediated synthesis of Co and Co₃O₄ NPs

Bacterial strain	Gram+/Gram−	NPs	Characterization	Size (nm)	Shape	References
Bacillus pasteurii	Gram+	Cobalt oxide	XRD, SEM, FE SEM, TEM, and HR-TEM	10–31	Irregular	[33]
Bacillus subtilis	Gram+	Cobalt oxide	XRD, SEM, FE SEM, TEM, and HR-TEM	6.6	Hollow rod	[72]
Brevibacterium casei	Gram+	Cobalt oxide	XRD, SEM, FE SEM, TEM, and HR-TEM	6	Quasi-spherical	[73]
Micrococcus lylae	Gram+	Cobalt oxide	XRD, SEM, FE SEM, TEM, and HR-TEM	8	Flower like	[77]
B. subtilis	Gram+	Cobalt oxide	FESE, M ELS-Z2, FESEM, XPS, and EPMA	3–5	Rods	[78]
M. lylae	Gram+	Cobalt oxide	XRD, TGA, FE-SEM, TEM, EDS, SAED, and HAADF-STEM	40	Spherical	[79]
M. lylae	Gram+	Cobalt	Zetasizer Nano system and FESEM	356 ± 55	Globular	[74]
B. subtilis	Gram+	Cobalt	Zetasizer Nano system and FESEM	NA	Rod shape	[74]
Escherichia coli	Gram−	Cobalt	Zetasizer Nano system and FESEM	473 ± 54	Rod shape	[74]
Paracoccus sp.	Gram−	Cobalt	Zetasizer Nano system and FESEM	NA	Biconcave	[74]
Haloarcula vallismortis	Gram−	Cobalt	Zetasizer Nano system and FESEM	NA	Globular	[74]
Proteus mirabilis	Gram−	Combine Cobalt	UV-vis, EDX, XRD, TEM, DLS, and PDI	57	Quasi-spherical	[76]
Bacillus thuringiensis	Gram+	Cobalt	XRD, TEM, FESEM, FTIR, and EDX	85.3	Face-cubic	[75]

Abbreviations: NPs, nanoparticles; NA, not available; SAED, selected area electron Diffraction; UV-vis, Ultraviolet visible spectroscopy; XPS, X-ray photoelectron spectroscopy; TEM, transmission electron microscopy; XRD, X-ray diffraction; HR-TEM, high-resolution transmission electron microscopy; EDX, energy-dispersive X-ray(spectroscopy); FTIR, Fourier-transform infrared spectroscopy; TGA, thermo gravimetric analysis; ATR-FTIR, attenuated total reflectance-Fourier transform infrared spectroscopy; FESEM, field emission scanning electron microscopy; EPMA, electron probe microanalyzer; HAAD-STEM, high-angle annular dark field scanning TEM; EDS, energy-dispersive X-ray spectroscopy.