TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preparation: No general method for the preparation of the non-natural derivative of naturally-occurring riboswitch, is given. Preferred Riboswitch: The riboswitch comprises an aptamer domain and an expression platform domain, where the aptamer domain and the expression platform domain are heterologous; or at least two aptamer domains and an expression platform domain, where at least one of the aptamer domains and the expression platform domain are heterologous (preferably at least two of the aptamer domains exhibit cooperative binding). The riboswitch comprises glnA motif, Downstream-peptide motif, SAM/SAH motif, crcB motif, pfl motif, yjdF motif, manA motif, wcaG motif, epsC motif, ykkC-III motif, psaA motif, psbA motif, PhotoRC-I motif, PhotoRC-II motif, or psbNH motif. The riboswitch is activated by a trigger molecule, where the riboswitch produces a signal when activated by the trigger molecule. The riboswitch has one of the consensus structures of Figure 1, Figure 2, Figure 3, Figure 4, or Figure 5 as given in the specification. Preferred Components: The aptamer domain is the aptamer domain of a naturally-occurring glutamine-responsive riboswitch, SAM-responsive riboswitch, SAH-responsive riboswitch, glutamine riboswitch, SAM/SAH riboswitch, glnA riboswitch, Downstream-peptide riboswitch, crcB riboswitch, pfl riboswitch, yjdF riboswitch, manA riboswitch, wcaG riboswitch, epsC riboswitch, ykkC-III riboswitch, psaA riboswitch, psbA riboswitch, PhotoRC-I riboswitch, PhotoRC-II riboswitch, or psbNH riboswitch. The aptamer domain has the consensus structure of an aptamer domain of the naturally-occurring riboswitch. The aptamer domain contains only base pair conservative changes of the naturally-occurring riboswitch. Preferred Method: In the method (M1), the riboswitch changes conformation when activated by the compound of interest, where the change in conformation produces a signal via a conformation dependent label, and the change in conformation causes a change in expression of an RNA linked to the riboswitch, where the change in expression produces a signal. In the method (M1), the signal is produced by a reporter protein expressed from the RNA linked to the riboswitch. In the method (M2), the cell (preferably bacterial cell) has been identified as being in need of altered gene expression. In the method (M2), the compound and the cell are brought into contact by administering the compound to a subject (preferably having a bacterial infection); the compound is administered in combination with another antimicrobial compound; and the compound inhibits bacterial growth in a biofilm. ACTIVITY - Antibacterial. No biological data given.    MECHANISM OF ACTION - None given.    ADMINISTRATION - Administration is oral, parenteral (e.g. intravenous, subcutaneous, intramuscular or intraperitoneal), transdermal or topical. No dosage details given.    EXAMPLE - No suitable example given.