Transcript Streptomyces - Blogs at Maryville University

Isolation of Streptomyces bacterial cultures for the induced
production of antibiotics: a preliminary analysis
Nick Kreutz, Catherine Gould, Alastair Pringle & Gabriel Colbeck
Abstract
Streptomyces bacteria are commonly found in soil and are well known for producing antibiotics. However,
only about .1-.5% of all strains have been identified. Due to the high potential for producing valuable
secondary metabolites, and the growing need for new, viable antibiotics, the isolation of novel strains of
Streptomyces could be critically important. Here, we isolated several cultures of Streptomyces, however we
failed to identify any antimicrobial properties.
Methods
-We collected soil from 6 locations in
and around St. Louis, Missouri: Tower
Grove Park, Oak Knoll Park, Maryville
University, Maryville Co-op garden,
Castlewood State Park, and Cliff Cave
State Park
-We isolated pure cultures of
Streptomyces, then examined how these
cultures affected growth of two test
organisms: E.coli and S.aureus
Methods
(laboratory)
-We treated soil with CaCO3 (10:1 w/w),
and incubated at 370 C for 4 days
-The mixture was suspended in ¼
strength Ringer Solution
-a 1:100 dilution was prepared from this
mixture
-We placed dilution tubes in a 45oC water
bath for 16 hrs
-Then we inoculated the dilutions on
Actinomycete Isolation Agar
-Streptomyces identified and isolated for
N=4
N=59
pure culture
N=72
N=35
Results
We were able to successfully isolate and
culture samples of Streptomyces
Field collection of soil samples
(above/below)
a)Cliff Cave Park b) Oak Knoll Park c) Maryville
Line Streak Method Results
Streptomyces
isolate
-Using sterile test tubes, we collected soil
from the rhizosphere, ~20 cm deep
Test
Organism
(E.coli)
Test Organism
(S.aureus)
We streaked a single line (visible above) of
Streptomyces down the middle of the plate.
After waiting two days we streaked test
organisms perpendicular to the isolate, but
found the Streptomyces to overgrow the
entire plate. This prevented the observation
of any inhibition.
Discussion
We were able to isolate and characterize
Streptomyces bacteria from three different
locations. We did not observe the inhibition of
test organisms, however it was noted the
Streptomyces seemingly overgrew the test
organisms. Future work will focus on:
• Controlling Strep growth such that we can
observe any potential antibiotic effects
• Isolating and examining different cultures of
Strep
• Examining the conditions under which these
newly isolated strains display the best growth
and/or antimicrobial activity
• Using genetic analysis to identify our strains
(and/or the closes relatives of these strains)
• Performing mutagenic analysis to try to
produce mutants of these strains that will have
stronger antimicrobial properties
• Doing chemical analysis of the specific
antimicrobial compounds
Acknowledgements
We would like to thank Dr. Postier and Jeff Carroll of
their assistance with this project.