The objective was
to characterize sediment Streptomyces from the Laguna Madre, a hypersaline estuary. We hypothesize that different
environmental factors (i.e., other microorganisms, salt concentration)
will result in spatial differences in Streptomyces communities. Streptomyces are of interest because
of their ability to produce a variety of secondary metabolites, such as antibiotics
and extracellular enzymes. Sediment samples were
collected from 3 sites in the Laguna Madre; two sites were proximal to each
other whereas the third site was distal to the others. Triplicate samples were collected at each site,
diluted and spread onto Marine 2216 Agar, Oatmeal agar (OA), and Starch Casein
agar (SCA). MA and OA plates were used to estimate the overall bacterial
density. SCA was used to estimate the density of Streptomyces at each
site and for Streptomyces isolation. Eleven Streptomyces isolates were characterized biochemically
using API20E® strips. Inhibitory assays were performed on the
isolates to determine if there was evidence for increased competition between
isolates found in the same location. Results suggest that salt
concentration at a specific site had an impact on the density and niche for the
microorganisms present; microbial density was similar amongst the close sites
vs. the isolated site. Biochemical tests indicated that organisms isolated from
all sites had similar enzymatic capabilities, including positive tests for
citrate utilization, gelatinase, and nitrite
utilization. This suggests Streptomyces in
Laguna Madre sediments occupy specialized niches. Current work includes further
isolations and characterizations of Streptomyces,
and BIOLOG®