The effect and role of environmental conditions on magnetosome synthesis

Abstract

Magnetotactic bacteria (MTB) are considered the model species for the controlled biomineralization of magnetic Fe oxide (magnetite, Fe3O4) or Fe sulfide (greigite, Fe3S4) nanocrystals in living organisms. In MTB, magnetic minerals form as membrane-bound, single-magnetic domain crystals known as magnetosomes and the synthesis of magnetosomes by MTB is a highly controlled process at the genetic level. Magnetosome crystals reveal highest purity and highest quality magnetic properties and are therefore increasingly sought after as novel nanoparticulate biomaterials for industrial and medical applications. In addition, “magnetofossils,” have been used as both past terrestrial and potential Martian life biosignature. However, until recently, the general belief was that the morphology of mature magnetite crystals formed by MTB was largely unaffected by environmental conditions. Here we review a series of studies that showed how changes in environmental factors such as temperature, pH, external Fe concentration, external magnetic fields, static or dynamic fluid conditions, and nutrient availability or concentrations can all affect the biomineralization of magnetite magnetosomes in MTB. The resulting variations in magnetic nanocrystals characteristics can have consequence both for their commercial value but also for their use as indicators for ancient life. In this paper we will review the recent findings regarding the influence of variable chemical and physical environmental control factors on the synthesis of magnetosome by MTB, and address the role of MTB in the global biogeochemical cycling of iron.

Diversity of Magnetotactic Bacteria from a French Pristine Mediterranean Area

“…MTB are assumed to play important roles in microbial ecology in sediment layers, particularly in both iron and sulfur cycles [10,16,21,23]. Ferrous and ferric ions are actively taken up and accumulated by MTB during the formation of magnetosomes [8].…”

Synthesis, Functionalization, and Design of Magnetic Nanoparticles for Theranostic Applications

“…In the case of material synthesis, diametrically opposed to the conventional chemical and mechanical synthetic routes which are energy consuming and require the usage of extreme conditions (such as high pressure, temperature, and acidity), biologically inspired synthetic routes take place under mild reaction conditions. [250] The controlled formation of stable and well-ordered solid inorganic compounds by biological systems, referred to as biomineralization, [38,251] has resolved many of the problems related to conventional synthetic routes by providing a strict control over particle size and shape that take part in many interesting activities in living organism. [250,252] In fact, this involves the uptake of specific elements from the environment by the organism, to form and maintain highly ordered inorganic mineral structures, ranging in size from nanometers to centimeters, under precise biological control.…”

Analysis of a population of magnetotactic bacteria of the Gulf of Gabès, Tunisia

“…Studies report the effect of environmental factors on their biosynthesis, such as pH, temperature, and oxygen concentration (Moisescu et al 2014). Moreover, some studies report the effect of Fe, Co, Mn, and other metals on their formation, and their incorporation in the cells (Keim et al 2009;Moisescu et al 2014;Staniland et al 2008). This property could be of great interest in depollution strategies (Bahaj et al 1993(Bahaj et al , 1994(Bahaj et al , 1998Yan et al 2012;Zhou et al 2012).…”

“…The unique properties of magnetosomes have attracted interest for their exploitation in a variety of applications. Studies report the effect of environmental factors on their biosynthesis, such as pH, temperature, and oxygen concentration (Moisescu et al 2014). Moreover, some studies report the effect of Fe, Co, Mn, and other metals on their formation, and their incorporation in the cells (Keim et al 2009;Moisescu et al 2014;Staniland et al 2008).…”