Biomedical Engineering Reference
In-Depth Information
12.2.3 Community Scale
A better understanding of the factors that affect growth and activity of microorganisms in
their environment requires insight into the relationships between different microbes in a commu-
nity. This insight is critical for defining input parameters for organism- or genome-scale modeling
as described earlier. It also is required to understand the contribution of ancillary microbes to the
primary contaminant degraders, such as the contribution of non-dechlorinators to promoting
dechlorination rates.
It is commonly observed that mixed cultures and consortia exhibit faster dechlorination
than pure cultures of dechlorinating organisms. This difference is likely due to the ability of
othermicrobestoprovidenutrients(e.g.,vitamin B12, acetate) and secondary metabolites to
the dechlorinators (Heimann et al., 2006 ; Johnson et al., 2009 ;Westetal., 2008 ). On a
physical environment level, these associated organisms help control the hydrogen partial
pressure, which provides the reducing environment required for dechlorination reactions to
be energetically favored. Associated organisms can potentially contribute a competitive
advantage to bioaugmentation inocula by controlling the concentrations of metabolites and
other required factors.
Understanding the complete metabolic potential of a bacterial community also can inform
the choice of electron donor at a site. For example, the donor provided during bioaugmentation
may be converted to a less tractable but higher efficiency donor through interspecies nutrient
transfer, which will influence community structure and dechlorination.
Understanding the interactions of microorganisms within a community is critical
for predicting the competitive advantage of an introduced community over indigenous
populations. With increased knowledge of the interactions within a bioaugmentation
culture, researchers can apply metabolic modeling on a community scale to describe the
potential effects of different site conditions. However, gathering the raw data to inform a
community-scale model is a large undertaking (Yu et al., 2010 ), and represents a current
bottleneck in this area.
Research Needs: Basic Science - Community Scale
Develop clever tools to identify interspecies metabolites and signals in communities of microbes.
Apply more systematic analyses of defined consortia.
Understand the ecological basis of competition.
Refer to the Enrichment Paradox below.
Apply genome scale models of metabolism to communities of organisms.
12.2.4 Environmental/Ecosystem and Earth Scale
Finally, interaction between microbial communities and their environment at a larger
scale is a critical consideration for successful bioaugmentation. Communities not only need
to contain the appropriate catabolic capabilities, but they also need to have the ability to adapt
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