Characterization of intracellular palladium nanoparticles synthesized by Desulfovibrio desulfuricans and Bacillus benzeovorans

• Published in: Journal of nanoparticle research : an interdisciplinary forum for nanoscale science and technology Vol. 17; no. 6; pp. 264 - 17
• Main Authors: Omajali, Jacob B., Mikheenko, Iryna P., Merroun, Mohamed L., Wood, Joseph, Macaskie, Lynne E.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 2015; Springer Nature B.V
• Subjects: Bacillus; Bacillus sphaericus; Bacteria; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cytoplasm; Desulfovibrio desulfuricans; Formates; Inorganic Chemistry; Lasers; Materials Science; Nanoparticles; Nanotechnology; Optical Devices; Optics; Palladium; Photonics; Physical Chemistry; Research Paper; Spectrometry; Strain; Synthesis; Synthesis; Biomedicine; Intracellular; Palladium nanoparticles; Icosahedron; Desulfovibrio desulfuricans; Bacillus benzeovorans
• ISSN: 1388-0764; 1572-896X
• DOI: 10.1007/s11051-015-3067-5

Early studies have focused on the synthesis of palladium nanoparticles within the periplasmic layer or on the outer membrane of
Desulfovibrio desulfuricans
and on the S-layer protein of
Bacillus sphaericus
. However, it has remained unclear whether the synthesis of palladium nanoparticles also takes place in the bacterial cell cytoplasm. This study reports the use of high-resolution scanning transmission electron microscopy with a high-angle annular dark field detector and energy dispersive X-ray spectrometry attachment to investigate the intracellular synthesis of palladium nanoparticles (Pd NPs). We show the intracellular synthesis of Pd NPs within cells of two anaerobic strains of
D. desulfuricans
and an aerobic strain of
B. benzeovorans
using hydrogen and formate as electron donors. The Pd nanoparticles were small and largely monodispersed, between 0.2 and 8 nm, occasionally from 9 to 12 nm with occasional larger nanoparticles. With
D. desulfuricans
NCIMB 8307 (but not
D
.
desulfuricans
NCIMB 8326) and with
B. benzeovorans
NCIMB 12555, the NPs were larger when made at the expense of formate, co-localizing with phosphate in the latter, and were crystalline, but were amorphous when made with H
2,
with no phosphorus association. The intracellular Pd nanoparticles were mainly icosahedrons with surfaces comprising {111} facets and about 5 % distortion when compared with that of bulk palladium. The particles were more concentrated in the cell cytoplasm than the cell wall, outer membrane, or periplasm. We provide new evidence for synthesis of palladium nanoparticles within the cytoplasm of bacteria, which were confirmed to maintain cellular integrity during this synthesis.