The oceans cover over two-thirds of our planet with an average depth of
about 3,800 m. The deep-sea area which occupies the great portion of the oceans
is basically nutrient-poor environment but has an important food source provided
by a continuous shower of marine snow consisted of mostly organic detritus
falling from the upper layers of the water column. However, little information
about complex forms, structures, and compositions of chemical mixtures in the
organic components deposited into the deep-sea sediments by downwelling of the
marine snow is available. In addition, it is eagerly anticipated to reveal the mechanisms
of the degradation, metabolism, and regeneration processes of the deposited organic
components and their relations to complex microbial ecosystems responsible for
the processes. Here we characterized and evaluated the chemical profiles in
deep-sea sediments collected at about 1000 m depth in Sagami bay using NMR-based
metabolomics approach, inductively-coupled plasma optical emission spectrometry
(ICP-OES)-based ionomic analysis, and pyrosequencing-based communitomics approach.
The evaluation of digitized and statistically computed NMR spectra was capable
to capture the differences and characteristics of organic compositions and
their complex chemical forms in individual sampling points including deep-sea, neritic,
and estuarine sediments. In addition, an evaluation approach for chemical
diversity based on the NMR spectral data was developed by modification and
optimization of the concept of “diversity index” in the field of ecology.
Furthermore, chemical diversities inversely related with microbial diversities
in deep-sea sediment were revealed by correlation analysis between chemical
diversity index based on the NMR spectra and microbial diversity index based on
the pyrosequencing analysis data.