The GFP expression plasmid (pGEM+GFP). The gfp was fused in-frame to the β-galactosidase α-gene in pGEM-Teasy plasmid. A small linker (L) was included (in-frame) between the gfp and β-galactosidase α-gene (lacZa). E. coli lac (lactose) promoter was upstream the genes. A start codon was in the β-galactosidase α-gene and a stop codon was included at the end of the gfp gene. The expression cassette contained an E. coli origin of replication (ori) and ampicillin resistance gene (AmpR).