The present invention discloses systems and methods for altering the color of bacterial bioluminescence via a fusion protein complex by fusing Discosoma sp. fluorescent protein mOrange (mOrange) with Vibrio harveyi luciferase. The fusion of mOrange to the N- or C-terminus of either α or β subunit of luciferase, via a short peptide linker produces fully active fusion enzymes. The fusion of mOrange to the N-terminus of luciferase α gives rise to a new 560-nm emission component. The same methodology may be used to alter bacterial bioluminescence color by covalent attachment of other suitable fluorescent proteins or chromophores to luciferase for generating multi-color sensors.