In recent years, culture-independent methods used to study
bacterial communities have received particular attention because
the majority of soil bacteria, i.e., more than 99%, are not accessible
by cultivation methods. However, molecular approaches are not yet
fully feasible to establish the potential to form macroaggregates of
a microbial community. Our approach using predominant cultur-
able isolates from microaggregates combined with measurements
of their soil aggregative ability appears to be a good starting point
to provide information on microbial populations that can function
as soil aggregators, since no molecular method is available to test
for soil aggregation as this metabolic potential can have different
genetic backgrounds. In addition, we acknowledge that the present
study is on a single dryland soil and that further investigations on
a variety of dryland soils are necessary. Also, more information on
the inﬂuence of seasonal change on the abundance of speciﬁc
microorganisms associated with aggregation is necessary to
understand the variations in their communities under different
tillage, crop rotation, and systems in semi-arid environments.
The authors express their sincere appreciation to L. L. Solberg for
technical assistance and to Dr. Mark West for his statistical analysis
assistance. We also acknowledge Dr. J. Jabro, Dr. W. Shelver, and
Dr. Tim Bourett for their constructivecomments on the manuscript.
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