The chemical formula of a magnetotactic bacterium

Abstract

Elucidation of the chemical logic of life is one of the grand challenges in biology, and essential to the progress of the upcoming field of synthetic biology. Treatment of microbial cells explicitly as a "chemical" species in controlled reaction (growth) environments has allowed fascinating discoveries of elemental formulae of a few species that have guided the modern views on compositions of a living cell. Application of mass and energy balances on living cells has proved to be useful in modeling of bioengineering systems, particularly in deriving optimized media compositions for growing microorganisms to maximize yields of desired bio-derived products by regulating intra-cellular metabolic networks. In this work, application of elemental mass balance during growth of Magnetospirillum gryphiswaldense in bioreactors has resulted in the discovery of the chemical formula of the magnetotactic bacterium. By developing a stoichiometric equation characterizing the formation of a magnetotactic bacterial cell, coupled with rigorous experimental measurements and robust calculations, we report the elemental formula of M. gryphiswaldense cell as CH(2.06)O(0.13)N(0.28)Fe(1.74×10(-3)). Remarkably, we find that iron metabolism during growth of this magnetotactic bacterium is much more correlated individually with carbon and nitrogen, compared to carbon and nitrogen with each other, indicating that iron serves more as a nutrient during bacterial growth rather than just a mineral. Magnetotactic bacteria have not only invoked some interest in the field of astrobiology for the last two decades, but are also prokaryotes having the unique ability of synthesizing membrane bound intracellular organelles. Our findings on these unique prokaryotes are a strong addition to the limited repertoire, of elemental compositions of living cells, aimed at exploring the chemical logic of life.

Synthesis and magnetic properties of organic multilayer films based on the layer‐by‐layer assembly

“…[27][28][29][30] Varieties of complexes containing novel synthetic polymers with nitrogen atoms or oxygen atoms and the corresponding complexes with transition metal ions or rare earth metal ions have been synthesized based on complicated chemical reactions. [31][32][33][34] Most of these polymers show interesting magnetic behaviors. However, among so many approaches used for the preparation of organic magnets, the simple method of self-assembly has received little attention so far.…”

Effects of dissolved oxygen concentration and iron addition on immediate-early gene expression of Magnetospirillum gryphiswaldense MSR-1

“…2B). This could probably be explained by the depletion of carbon source in the culture, since carbon is crucial for magnetosome formation as an energy source (Naresh et al 2012). Indeed, carbon is particularly important in the transport process of magnetite synthesis (Schüler and Baeuerlein 1996), and is the limiting source for consumption of nitrogen and iron in the later phase of growth (Naresh et al 2012).…”

The effect and role of environmental conditions on magnetosome synthesis

“…Recently, it was suggested that during MTB growth, iron (Fe) also serves as a nutrient rather than just a storage mineral (Naresh et al, 2012). This was concluded from the fact that Fe was more correlated with C and N, compared to the correlation between C and N which are used mainly as an energy source (C), and for biosynthetic processes (N).…”

“…As to the Fe and N relationship, during the lag and exponential growth phases there is a substantial demand of N to form proteins for assembly of magnetosome vesicles, and to transport and incorporate Fe for magnetosome synthesis. After the vesicles assemble, proteins promote the nucleation of Fe crystals leading to MTB magnetosomes (Naresh et al, 2012). This was clearly demonstrated recently by Siponen et al (2013), who showed that the magnetosome associated protein MamP plays the crucial role in magnetite crystal growth inside MTB (Siponen et al, 2013).…”