Magnetotactic Bacteria as Potential Sources of Bioproducts

Abstract

Magnetotactic bacteria (MTB) produce intracellular organelles called magnetosomes which are magnetic nanoparticles composed of magnetite (Fe3O4) or greigite (Fe3S4) enveloped by a lipid bilayer. The synthesis of a magnetosome is through a genetically controlled process in which the bacterium has control over the composition, direction of crystal growth, and the size and shape of the mineral crystal. As a result of this control, magnetosomes have narrow and uniform size ranges, relatively specific magnetic and crystalline properties, and an enveloping biological membrane. These features are not observed in magnetic particles produced abiotically and thus magnetosomes are of great interest in biotechnology. Most currently described MTB have been isolated from saline or brackish environments and the availability of their genomes has contributed to a better understanding and culturing of these fastidious microorganisms. Moreover, genome sequences have allowed researchers to study genes related to magnetosome production for the synthesis of magnetic particles for use in future commercial and medical applications. Here, we review the current information on the biology of MTB and apply, for the first time, a genome mining strategy on these microorganisms to search for secondary metabolite synthesis genes. More specifically, we discovered that the genome of the cultured MTB Magnetovibrio blakemorei, among other MTB, contains several metabolic pathways for the synthesis of secondary metabolites and other compounds, thereby raising the possibility of the co-production of new bioactive molecules along with magnetosomes by this species.

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

“…Increasing the applied field or the concentration of bacteria would diminish this problem. Another possibility would be to increase the number of chains and/or magnetosomes per cell, something that in fact, has already been proved to be feasible …”

Light irradiation helps magnetotactic bacteria eliminate intracellular reactive oxygen species

“…One of the most abundant and conserved magnetosome-associated genes is mamA. Its protein has multiple domains with TPR motifs (protein-protein interactions), may act as multiprotein assembly site and stabilizes the magnetosome chain (Komeili et al, 2004;Araujo et al, 2015). Some of the genes play a role in controlling the size and morphology of magnetite crystals in MTB, including mms6, mms13, mmsF (Scheffel et al, 2006;Yoshino and Matsunaga, 2006;Murat et al, 2012).…”

Magnetospirillum caucaseum sp. nov., Magnetospirillum marisnigri sp. nov. and Magnetospirillum moscoviense sp. nov., freshwater magnetotactic bacteria isolated from three distinct geographical locations in European Russia

“…M. gryphiswaldense MSR-1 T and 'M. magneticum' AMB-1 are of great importance as model strains for magnetosome formation studies and as potential producers of bacterial magnetic nanoparticles for a variety of biotechnological applications (Murat et al, 2010;Lohße et al, 2011;Yan et al, 2012;Alphandéry, 2014;Araujo et al, 2015). The genus Magnetospirillum includes both magnetotactic strains and those that do not produce magnetosomes, namely 'Magnetospirillum bellicus' VDY and 'Magnetospirillum aberrantis' SpK, the names of which have been not yet validly published (Thrash et al, 2010;Gorlenko et al, 2011).…”