Bacterial Communities Established in Bauxite Residues
with Different Restoration Histories
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Abstract
Bauxite
residue is the alkaline byproduct generated when alumina
is extracted from bauxite ores and is commonly deposited in impoundments.
These sites represent hostile environments with increased salinity
and alkalinity and little prospect of revegetation when left untreated.
This study reports the establishment of bacterial communities in bauxite
residues with and without restoration amendments (compost and gypsum
addition, revegetation) in samples taken in 2009 and 2011 from 0 to
10 cm depth. DNA fingerprint analysis of bacterial communities based
on 16S rRNA gene fragments revealed a significant separation of the
untreated site and the amended sites in both sampling years. 16S amplicon
analysis (454 FLX pyrosequencing) revealed significantly lower alpha
diversities in the unamended in comparison to the amended sites and
hierarchical clustering separated the unamended site from the amended
sites. The taxonomic analysis revealed that the restoration resulted
in the accumulation of bacterial populations typical for soils including <i>Acidobacteriaceae, Nitrosomonadaceae</i>, and <i>Caulobacteraceae</i>. In contrast, the unamended site was dominated by taxonomic groups
including <i>Beijerinckiaceae</i>, <i>Xanthomonadaceae</i>, <i>Acetobacteraceae</i>, and <i>Chitinophagaceae</i>, repeatedly associated with alkaline salt lakes and sediments. While
bacterial communities developed in the initially sterile bauxite residue,
only the restoration treatments created diverse soil-like bacterial
communities alongside diverse vegetation on the surface