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Marine organisms have
been the source of a large number of unique biologically active
compounds. These novel molecules have been shown to have
activities useful in the medical field (e.g. antibiotic and
anticancer agents) as well as in industrial applications (e.g.
halogenation enzymes). Bromination is a chemical halogenation
process important in manufacturing of a variety of substances
including flame-retardants and antibacterial drugs. Chemical
bromination lacks specificity and results in the formation of
undesirable byproducts. In addition the elemental bromine
necessary for this process is extremely toxic and a health
hazard. Therefore brominating enzymes have become increasingly
attractive. These enzymes have been isolated from marine algae
as well as soil microorganisms such as Streptomyces
sp. High levels of halogenated substances are common and
natural sources of these substances are marine organisms such as
polychaete and hemichordate worms. Hemichordate or acorn worms
inhabit mucus-lined burrows in the sediment of shallow water.
High concentrations of brominated compounds have been found
externally to the worms in the mucus lining these burrows.
Therefore bacteria associated with the slime of the worms may
play an important role in the production of the brominated
aromatics.
Proposed Undergraduate Role
in the Investigation
The undergraduate students participating in RUMBA will serve a
vital role in this investigation by screening and characterize
bromoperoxidase activity in acorn worm isolates.
RUMBA students will have the opportunity to develop and test
their own ideas within the framework of this research.
Examples of possible projects students can become
interested in investigating are: (1) screening of acorn worm
isolates for bromoperoxidase activity; (2) characterization of
positive isolates using biochemical tests and molecular
approaches such as amplification of rRNA sequences; (3)
molecular screening of the bromoperoxidase-producing isolates
for the presence of FADH2 dependent halogenase genes;
and (4) cloning and expression of genes obtained.
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Dr. Rech teaching an upper division
microbiology class.
We began our studies of the bromination
enzymes found in marine bacteria two years ago. During the
first year a group of four undergraduates in my laboratory were
able to isolate 40 bacterial strains which were assigned to 30
separate groups based on their colony morphology. During the
past year the undergraduates started screening isolates for
bromoperoxidase production. The screening involves the partial
purification of the enzyme. Streptomyces aureofaciens, a
soil bacterium, which produces bromoperoxidase, is used as a
positive control. We have screened four isolates and two
organisms have shown high bromoperoxidase activity when compared
with the positive control. Recent studies have shown that some
bacterial haloperoxidases and perhydrolases are lacking
halogenation specificity12. However, it was
demonstrated that the same strains also harbor FADH2
dependent halogenases, which are very specific.
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