The role of the ferric uptake gene (fur) in burkholderia sp. usm b20
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Date
2014
Authors
Mohamad, Ahmad Faisal
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Abstract
Iron is an element that plays an important role in biochemical reactions in all living
things. The lack of this element stimulates a pathogenic bacterium to release virulent
factors in order to survive. This study was conducted to observe the role of a ferric ion
transport regulator gene named fur in bacterial virulence. Strain Burkholderia sp. USM
B20 which was isolated from a leguminous plant Mucuna bracteata was used as a
model microorganism. Sequence analysis of the 16S rDNA of this bacterium showed
that it shared 99% identity with Burkholderia vietnamiensis. To elucidate the role of the
fur gene, a mutant strain was formed. A plasmid called pTS414 which carried the levan
sucrase and trimethoprim antibiotic resistance genes were constructed. This antibiotic
resistance trimethoprim gene was regulated by a promoter derived from the B.
vietnamiensis 16S rDNA gene. This gene was found to function in Burkholderia sp.
B20. Subsequently, the DNA present on the left and right of the fur gene were cloned so
that the fur gene was flanked in the plasmid. This assembly was done to develop an
allele replacement vector to mutate the chromosomal copy of the fur gene in
Burkholderia sp. B20. This allele replacement vector was transformed into Escherichia
coli S17 lambda pir and subsequently moved into Burkholderia sp. USM B20 through
conjugation. A fur- mutant that had the fur gene replaced with the trimethoprim resistant
gene was successfully generated. Validation of this mutant was done using PCR. A
comparative study showed that biofilm production by this mutant was evidently lower
than the wild type strain. This mutant is also unable to produce a quorum sensing signal.
No change was seen in the production of protease and lipase enzymes. As a whole, it
can be described that the fur gene influences a several of features in Burkholderia sp.
B20 with respect to virulence.