INGEBI   02650
INSTITUTO DE INVESTIGACIONES EN INGENIERIA GENETICA Y BIOLOGIA MOLECULAR "DR. HECTOR N TORRES"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Neutral And Niche-Oriented Assembly of Activated Sludge Floc
Autor/es:
AYARZA, J. M.; ERIJMAN, L.
Lugar:
Seattle, WA
Reunión:
Congreso; 13th Internacional Symposium on Microbial Ecology ISME-13; 2010
Institución organizadora:
Internacional Society for Microbial Ecology-ISME
Resumen:
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Understanding the processes that
generate patterns of community structure is a central focus of ecological
research. With that aim, we manipulated the diversity of bacterial activated
sludge to test the influence of the diversity and composition of source
bacterial communities on the dynamics of activated sludge floc assembly in lab-scale
bioreactors.
Three sets of experiments were
performed. In the first set of experiments four replicate lab-scale reactors
were seeded with sludge from a full-scale wastewater treatment plant (WWTP).
Secondly, four laboratory scale reactors were replicates of a mixture of sludge
from four different full-scale WWTP, added in equal proportions. In the third
experiment, each of four lab-scale reactors contained 70% of sludge from a
single full-scale WWTP, and 10% of sludge from the remaining 3 plants. Changes
in bacterial community profiles were analyzed for a period of 10 solid
retention time using denaturing gradient gel electrophoresis (DGGE) of RT-PCR
amplified 16S rRNA.
Fingerprinting of each set of reactors,
including those started with the same source communities added in different
proportions, converged to patterns that were more similar than expected
by chance, suggesting a deterministic selection in floc development. Evidence for neutral dynamics was suggested by
the dependence of the rate of replacement of species on the number of available
species in the source community. Further indication of stochastic dynamics was
obtained by the application of the Sloan neutral model for prokaryotes. The
fitting of the observed data to the model predictions revealed that the
importance of the stochastic component increased with higher diversity.
Our results illustrate how both neutral and
deterministic dynamics operate together in the assembly of the bacterial floc,
and show that the balance of the two depends on the diversity of the source
community.