Magnetotactic bacteria

About: Magnetotactic bacteria is a research topic. Over the lifetime, 1118 publications have been published within this topic receiving 43741 citations.

Toxicity assessment of magnetosomes in different models

Abstract: Magnetosomes are nanosized iron oxide particles surrounded by lipid membrane synthesized by magnetotactic bacteria (MTB). Magnetosomes have been exploited for a broad range of biomedical and biotechnological applications. Due to their enormous potential in the biomedical field, its safety assessment is necessary. Detailed research on the toxicity of the magnetosomes was not studied so far. This study focuses on the toxicity assessment of magnetosomes in various models such as Human RBC’s, WBC’s, mouse macrophage cell line (J774), Onion root tip and fish (Oreochromis mossambicus). The toxicity in RBC models revealed that the RBC’s are unaltered up to a concentration of 150 µg/ml, and its morphology was not affected. The genotoxicity studies on WBC’s showed that there were no detectable chromosomal aberrations up to a concentration of 100 µg/ml. Similarly, there were no detectable morphological changes observed on the magnetosome-treated J774 cells, and the viability of the cells was above 90% at all the tested concentrations. Furthermore, the magnetosomes are not toxic to the fish (O. mossambicus), as no mortality or behavioural changes were observed in the magnetosome-treated groups. Histopathological analysis of the same reveals no damage in the muscle and gill sections. Overall, the results suggest that the magnetosomes are safe at lower concentration and does not pose any potential risk to the ecosystem.

Magnetic microstructure of iron sulfide crystals in magnetotactic bacteria from off-axis electron holography

Abstract: Transmission electron microscopy, off-axis electron holography and energy-selected imaging were used to study the crystallography, morphology, and magnetic microstructure of nanoscale greigite (Fe3S4) magnetosomes in magnetotactic bacteria from a sulfidic habitat. The greigite magnetosomes were organized in chains, but were less ordered than magnetite magnetosomes in other bacteria. Nevertheless, the magnetosomes comprise a permanent magnetic dipole, sufficient for magnetotaxis.

Magnetotactic Bacteria: Magnetism Beyond Magnetosomes

Abstract: Magnetotactic bacteria are a group of organisms deeply studied in the last years due to their interesting magnetic behavior and potential applications in nanometrology, hyperthermia, and biosensor devices. One intrinsic common characteristic is the presence, inside the bacteria, of magnetic nanoparticles called magnetosomes. The role of magnetosomes as bacterial tools to orient the bacteria and find new habitats is universally accepted, but the way they develop still is not fully understood. A strain of Magnetospirillum magnetotacticum was grown and investigated at the nanoscale using transmission electron microscopy and atomic/magnetic force microscopy techniques. Magnetosomes were observed as well as long filaments with magnetic response that could be associated to the actin-like filaments being crucial to allow the nanoparticles orientation and magnetosomes formation. To the best of our knowledge, this paper is the first to visualize these reproducible long-range size magnetic crystalline structures.

Combined Approaches for Characterization of an Uncultivated Magnetotactic coccus from Lake Miyun near Beijing

Abstract: This paper reports the features of an as yet uncultivated magnetotactic coccus, named MYC-1, recently found from surface sediments of Lake Miyun near Beijing. Light microscope and Bacteriodrome analyses demonstrate that MYC-1 is north-seeking in the Earth's magnetic field. Transmission electron microscope (TEM) attached with energy-dispersive X-ray analyses reveal that this coccus contains a single chain of magnetosomes, containing approximately 10 large iron-oxide crystals. Morphology of these crystals is featured by prism with a mean length and width of 117 nm and 95 nm (statistics from 281 crystals), respectively; it yields an aspect factor of 1.24. A linear relationship (r2 = 0.83) clearly exists between the length and width of crystals. In agreement with previous results, we observed that the size distribution of the MYC-1 is distinctly asymmetric with cut off toward larger sizes, which is the opposite of non-biogenic crystals. Low-temperature magnetic measurements on bulk bacteria samples show a dis...

Alpha-Oxo Acids Assisted Transformation of FeS to Fe3S4 at Low Temperature: Implications for Abiotic, Biotic, and Prebiotic Mineralization.

Abstract: The mineral greigite (Fe3S4) distributes widely in anoxic marine and lake sedimentary systems, with important implications for magnetostratigraphy and paleomagnetism. In living organisms, magnetotactic bacteria can synthesize greigite grains with regular sizes and morphologies. The cubic Fe3S4 structure also occurs as an integral constituent and active center in a family of iron-sulfur proteins in all life-forms on Earth. This basic biochemistry shared by all organisms implies that the Fe3S4 structure might have evolved in the first protocell. Therefore, greigite is of general interest in geochemistry, geophysics, biomineralogy, and origin-of-life sciences. However, the growth of thermodynamically metastable Fe3S4 crystals often requires strictly defined conditions because both Fe and S show variable valences and it is hard to tune their valence fluctuation. Here, we show that freshly precipitated FeS can be selectively oxidized to form greigite in the presence of α-oxo acids, even at room temper...