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Appl. Environ. Microbiol., Nov 1996, 3922-3928, Vol 62, No. 11
CM Santegoeds, SC Nold and DM Ward
Previous studies investigating microbial diversity in the Octopus Spring
cyanobacterial mat community (Yellowstone National Park) have shown a
discrepancy between bacterial populations observed by molecular retrieval
and cultivation techniques. To investigate how selective enrichment culture
techniques affect species composition, we used denaturing gradient gel
electrophoresis (DGGE) separation of PCR- amplified 16S rRNA gene fragments
to monitor the populations contained within enrichment cultures of aerobic
chemoorganotrophic bacteria from the ca. 50 degrees C region of the mat
community. By varying the degree of dilution of the inoculum, medium
composition, and enrichment conditions and duration and by analyzing the
cultures by DGGE, we detected 14 unique 16S rRNA sequence types. These
corresponded to alpha- , beta-, gamma-, and delta-proteobacteria, Thermus
relatives, and gram- positive bacteria with high G + C ratio and, at the
highest inoculum dilutions, Chloroflexus aurantiacus relatives, which were
estimated to still be approximately 300 times less abundant than cells of
the mat primary producer, Synechococcus spp. Only three of these
populations were previously cultivated on solidified medium after similar
enrichment. Only two of these population have 16S rRNA sequences which were
previously cloned directly from the mat. These results reveal a diversity
of bacterial populations in enrichment culture which were not detected by
either molecular retrieval or strain purification techniques.
Copyright © 1996, American Society for Microbiology
Denaturing gradient gel electrophoresis used to monitor the enrichment culture of aerobic chemoorganotrophic bacteria from a hot spring cyanobacterial mat
Department of Microbiology, Montana State University, Bozeman 59717, USA.
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