Abstract: A nucleic acid comprising a continuous nucleotide sequence, containing: (i) a gene encoding LuxA, (ii) a gene encoding LuxB, (iii) a gene encoding LuxC, (iv) a gene encoding LuxD, (v) a gene encoding LuxE, wherein each of the genes is under the control of a promoter heterologous to the respective gene, and wherein all of the genes together with the promoter are contained in a single nucleotide sequence in a row. The vectors and host cells comprise the nucleic acid. Methods of producing a host cell and methods and uses for detecting an environmental effect and a kit therefor.