Microorganisms can be easily used for genetic tailoring by means of genetic tools to study the modifications in environmental conditions. Reporter genes are tagged with multicoloured fluorescent proteins which aid in identifying the chemical effects prevailing in the environment. The engineered microorganisms are then used for whole cell array set-up on silicon chips and diverse optic fibres to get bioavailability of pollutants which could be correlated with their impact on life (Belkin, 2003).
Reporter gene is expressed when it is fused with a promoter target sequences. Thus expression can be observed by the appearance of the reporter gene, in view of the fact that reporter is tagged with the active gene of interest. The promoter is tagged with a marker gene such as GFP, a stable molecule used to identify the phenotype or the genotype of the transformed organism. Luminescence markers: emit light making the selection process easy and simple moreover, they measure the cellular activity swiftly. FACS (fluorescence activated cell sorting) is performed with GFP, YFP and BFP i.e. green, yellow and blue fluorescent proteins respectively. The molecules do not require oxygen for fluorescence (Belkin, 2003).
In transgenic organisms GFP molecule is integrated with active gene, expression of gene is observed through green glow under UV radiation. Transgenic organisms of various species such as E coli, C elegans, Drosophila were made to glow by inserting GFP reporter gene. Toxicity of GFP is not observed in both prokaryotic and eukaryotic organism, indicating the safety of the molecule. Small size of GFP makes it ideal for reporter gene or if GFP is tagged at the end of the active gene, it is expressed with the gene once the gene undergoes the process of transcription and translation, however, expression of GFP does not affect the protein.