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]. A recent study in a pelagic
carbonate sediment has shown that magnetofossils contain
30–60 % of all secondary iron phases, meaning that[30 %
of the Fe cycle was certainly driven by these bacteria [12].
MTB are microaerophiles or anaerobes and are therefore
found at the oxic–anoxic interface transition zone (OATZ)
of the sediments. A recent report of MTB from pelagic red
clays has shown that MTB might be found also in oxic
settings decoupled from the occurrence of an OATZ [25].