Rock magnetic properties of uncultured magnetotactic bacteria

摘要: Abstract Understanding the magnetic properties of magnetite crystals (Fe3O4) produced by magnetotactic bacteria (MTBs) is fundamental interest in fields geosciences, biomineralization, fine particle magnetism, and planetary sciences. The database bulk measurements on MTBs is, however, still too sparse to allow for generalizations due difficulties obtaining cells sufficient quantities from natural environments, fact that only a few cultivable strains are available. Here we report first series two air-dried samples containing solely (wild-type cocci Magnetobacterium bavaricum), which were directly isolated carbonaceous lake sediments. Systematic rock studies show that: 1) magnetosomes dominated single-domain (SD) magnetite; 2) have delta ratios δFC / δZFC higher than 2; 3) measured low-temperature remanence cycling curves as well first-order-reversal-curve (FORC) diagrams significantly different those synthetic SD-magnetite samples; 4) Verwey transition temperature (Tv, ∼100 K) MTB distinctly lower stoichiometric 120–125 K). Our results provide new insights bacterial advance use proxies decoding paleomagnetic signals sediments magnetite.