الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
SUMMARY
Tributyltin can be highly toxic to many eukaryotic and prokaryotic
organisms and have also been identified as immune system inhibitor and
endocrine disruptors in humans; it was used in antifouling paints to prevent
fouling it’s also used in industrial purposes as biocide and preservative.
The main purpose of this thesis was to isolate new bacterial strains
able to degrade TBT into less toxic compounds (DBT&MBT) and to
elucidate the mechanism of resistance to TBT.
The obtained result can be summarized as follows:
1. Three bacterial strains were isolated; they have the ability to grow on
TBT as sole source of carbon and energy from samples collected
from the Mediterranean Sea in Abu Qir port, Alexandria, Egypt.
2. The three isolates were identified morphologically, biochemically
and by the 16S rRNA gene sequence analysis, the isolates were
identified as Sphingobiumsp.HS1 and StenotrophomonasspHS2.
&RhizobiumborboriHS5. HS5 and were tested for antibiotic
sensitivity.
3. The phylogenetic analysis of the isolated strains was constructed in
comparison with other related organic compound degraders, by
neighbor-joining distance analysis of their 16S rRNA gene sequence
Stenotrophomonas sp HS2was highly similar to Stenotrophomonas
chelatiphaga strain LPM-5in the GenBank, which is EDTAdegrading
bacterium, and 98% with Stenotrophomonas maltophilia
which is monocyclic hydrocarbon degrading bacterium.
Summary
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4. TBT sensitivity test was determined and Rhizobium borbori HS5 and
Sphingobiumsp.HS1 were able to resist TBT up to 2Mm while
Stenotrophomonas sp. HS2 was able to resist TBT up to 3Mm.
5. TBT used by Stenotrophomonas sp. HS2was analyzed using GC-FID
(gas chromatography with flame ionization detector).
6. The phylogenetic analysis of the amplified fragment obtained using
primer sets (sugEF, sugER2) was constructed in comparison with the
other similar gene sequences from NCBI. It was found Arsenic
efflux pump protein (homology 93%) with aryl sulfatase protien in
Stenotrophomonas maltophilia and 87% homology with arsenic
efflux pump protein in Xanthomonas oryzea.
7. Finally, These results suggest that it may be possible to expand the
range of biodegradable TBT congeners and this leads to more
accurate assessments of pollutant biodegradation and the impact of
remediation technologies.