Abstract:
The lux operon is the cluster of genes that encode luminescence in light emitting
bacteria. Expression of this operon or parts of it can be utilized in the construction of
biosensors, which are genetically modified organisms, often bacteria that can be used
to detect and measure environmental chemical factors such as pollutants. This type
of biosensors is constructed in such a way that light emission occurs due an
environmental signal ‘sensed’ by a ‘sensor gene element’. The sensor element acts
as a promoter that triggers on the expression of a reporter gene element, for example
lux genes, fixed immediately downstream to it. The intensity of the light emission
can be measured using a luminometer and it gives not only a quantitative
measurement of the environmental factor but also an indication of the bioavailability
of the factor.
The lux operon is consisted of seven genes, i.e. luxR, I and CDABE. Each of the genes
is responsible for a specific function. The luxR and luxI products act as the auto
inducer for the gene expression, which are not needed in a biosensor because there
is the sensor element to act as the promoter.
The plasmid pSB2025 constructed previously by another research group and which
contains sections of the lux operon modified for the expression in both Gram negative
and positive bacteria, provides a promoter-less gene sequence that can be used in the
construction of biosensors with a suitable promoter of choice. Promoters of genes of
various bacteria that are expressed upon exposure to heavy metals or DNA damaging
factors, would be ideal sensor elements in the construction of biosensors that can be
used to detect and monitor environmental pollution caused by such factors. Such
biosensors would provide a tool cheaper than chemical analysis of pollutants.
