TITLE:
Composition of the Microorganism Community Found in the Soil Cover on the Dried Seabed of the Aral Sea
AUTHORS:
Galina Stulina, Nadejda Verkhovtseva, Maria Gorbacheva
KEYWORDS:
Microorganism Community, Diversity of Microorganisms, Dried Seabed, Soil formation, Aral Sea
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.7 No.8,
August
12,
2019
ABSTRACT: As a result of the Aral Sea shrinkage, the unique
freshwater body has given place to a huge bitter-saline lake with an area 3.5
times less, volume 6 times less and water salinity 10 times larger than in
1960, and the saline desert at the interface between three sand deserts with an
area of more than 5 million ha, being unstable ecological zone. The exposed
ground is illustrative of arid salt-accumulation, where was created specific
type of soil-costal solonchak. The origination of life in the soil of the dried
bed starts long before the occurrence of external characteristics. This process
can be traced only by studying the microbiological composition of soil.
Research in this direction, was conducted in order to determine the
microbiological composition of soil for horizons of one typical profile of
solonchak. The research objective was to determine microorganism species in the
soil on the dried seabed, identify changes in the microorganism community along
the soil profile and dependence on duration of the drying process.
Additionally, we paid attention to a vegetation effect on the composition of
microorganisms. Soil samples were taken along a transect from the sea to the
mainland, selected from the different depth of soil profiles taken under or
near plant (saxaul). The method Gas chromatography mass-spectrometry was used.
Bacteria of the community of microorganisms in different parts of the soil
cover on the dried seabed of the Aral Sea and on the mainland belong to five
bacterial phyla: Proteobacteria Actinobacteria Firmicutes Bacteroidetes and
Deinococcus-Thermus. In general, 59 bacterial species of 43 genera were
reconstructed. The total population varied from 105 cells/g to 108 cells/g of the soil. The association Aeromonas hydrophila-Arthrobacter sp. played the key role at
the first stages of the soil formation process on the dried seabed of the Aral
Sea. This association is followed by salt-resistant Agrobacterium sp. and humus-accumulating Propionibacterium
freudenreichii, activity of which
is also very important for the formation of the soil cover. The studying
properties of the dried seabed cover of both salt composition and microbiological
composition made it possible to trace the formation of primary soil on marine
sediments with the subsequent formation of desert-type soil.