1 research outputs found
Manganese-Cycling Microbial Communities Inside Deep-Sea Manganese Nodules
Polymetallic
nodules (manganese nodules) have been formed on deep
sea sediments over millions of years and are currently explored for
their economic potential, particularly for cobalt, nickel, copper,
and manganese. Here we explored microbial communities inside nodules
from the northeastern equatorial Pacific. The nodules have a large
connected pore space with a huge inner surface of 120 m<sup>2</sup>/g as analyzed by computer tomography and BET measurements. X-ray
photoelectron spectroscopy (XPS) and electron microprobe analysis
revealed a complex chemical fine structure. This consisted of layers
with highly variable Mn/Fe ratios (<1 to >500) and mainly of
turbostratic
phyllomanganates such as 7 and 10 Ã… vernadites alternating with
layers of Fe-bearing vernadite (δ-MnO<sub>2</sub>) epitaxially
intergrown with amorphous feroxyhyte (δ-FeOOH). Using molecular
16S rRNA gene techniques (clone libraries, pyrosequencing, and real-time
PCR), we show that polymetallic nodules provide a suitable habitat
for prokaryotes with an abundant and diverse prokaryotic community
dominated by nodule-specific MnÂ(IV)-reducing and MnÂ(II)-oxidizing
bacteria. These bacteria were not detected in the nodule-surrounding
sediment. The high abundance and dominance of Mn-cycling bacteria
in the manganese nodules argue for a biologically driven closed manganese
cycle inside the nodules relevant for their formation and potential
degradation