Summary
A combination of microscopic, molecular and biogeochemical methods was used to study the structure, phylogenetics and vertical distribution of spherical multicellular magnetotactic prokaryotes (
MMPs
) of intertidal sediments in the
Y
ellow
S
ea. These
MMPs
were 5.5 μm in diameter and composed of approximately 15–30 cells. They synthesized bullet‐shaped magnetites in chains or clusters. Phylogenetic analysis of 16
S rRNA
gene sequences suggested that these
MMPs
represent a novel species affiliated to the
D
eltaproteobacteria.
To study their vertical distribution and the relationship to geochemical parameters, sediment cores were collected after the redox potential was measured
in situ
. The sediments were composed of yellow, grey and black layers from the surface to depth. The spherical
MMPs
were concentrated near the grey‐black layer transition at a depth of 8–12 cm, while coccoid‐shaped magnetotactic bacteria near the yellow‐grey layer transition at a depth of 3–5 cm. The intertidal
MMPs
showed a deeper distribution at more reduced environments than coccoid‐shaped magnetotactic bacteria, and
MMPs
in lagoon sediments. Additionally the
MMPs
were concentrated significantly in layers with high proportion of fine sand and total organic carbon, rich in leachable iron but poor in nitrate. These results show an adaptation of spherical
MMPs
to the peculiar intertidal sediment habitat.