A genetically modified microbial cell for intracellular biosynthesis of a cellular metabolite comprising: a. a first nucleic acid molecule wherein the translation of said molecule yields a transcription factor biosensor; and any one selected from the group consisting of: b. a second nucleic acid molecule comprising a coding sequence encoding an essential protein required for cell growth and/or survival, wherein the second nucleic acid molecule is operably linked to an inducible first promoter; wherein expression of said essential protein encoded by said second nucleic acid molecule is induced when said biosensor and said cellular metabolite form a complex and bind to said inducible first promoter; c. a second nucleic acid molecule comprising a coding sequence encoding an anti-toxin protein required for cell growth and/or survival and cognate to a toxin protein, wherein the amino acid sequence of said anti-toxin protein has at least 80% sequence identity to a sequence selected from the group consisting of SEQ ID No.: 2, 38, 42, and 46, and wherein the second nucleic acid molecule is operably linked to an inducible first promoter; and a third nucleic acid molecule encoding said toxin protein that is toxic for cell growth and/or survival, wherein the amino acid sequence of said toxin protein has at least 80% sequence identity to a sequence selected from the group consisting of SEQ ID No.: 3, 36, 40 and 44, wherein said third nucleic acid molecule comprises a coding sequence operably linked to a constitutive second promoter; wherein expression of said anti-toxin protein encoded by said second nucleic acid molecule is induced when said biosensor and said cellular metabolite form a complex and bind to said inducible first promoter; and d. a second nucleic acid molecule encoding a protein that is toxic for cell growth and/or survival, wherein the amino acid sequence of said protein has at least 80% sequence identity to a sequence selected from the group consisting of SEQ ID No.: 3, 36, 40 and 44, wherein said second nucleic acid molecule comprises a coding sequence operably linked to a promoter; wherein expression of said protein is prevented when said biosensor and said cellular metabolite form a complex and bind to said promoter; whereby arrest of growth and /or death of said cell due to an absence of complex formation does not depend on externally supplied growth inhibitor or growth retardant, and wherein said metabolite has a high fitness cost of production selected from among ≥ 5 %, ≥10%, ≥15%, ≥20%, and ≥25% measured relative to the growth rate of a reference microbial cell where production is inactivated. a. a first nucleic acid molecule wherein the translation of said molecule yields a transcription factor biosensor; and any one selected from the group consisting of: b. a second nucleic acid molecule comprising a coding sequence encoding an essential protein required for cell growth and/or survival, wherein the second nucleic acid molecule is operably linked to an inducible first promoter; wherein expression of said essential protein encoded by said second nucleic acid molecule is induced when said biosensor and said cellular metabolite form a complex and bind to said inducible first promoter; c. a second nucleic acid molecule comprising a coding sequence encoding an anti-toxin protein required for cell growth and/or survival and cognate to a toxin protein, wherein the amino acid sequence of said anti-toxin protein has at least 80% sequence identity to a sequence selected from the group consisting of SEQ ID No.: 2, 38, 42, and 46, and wherein the second nucleic acid molecule is operably linked to an inducible first promoter; and a third nucleic acid molecule encoding said toxin protein that is toxic for cell growth and/or survival, wherein the amino acid sequence of said toxin protein has at least 80% sequence identity to a sequence selected from the group consisting of SEQ ID No.: 3, 36, 40 and 44, wherein said third nucleic acid molecule comprises a coding sequence operably linked to a constitutive second promoter; wherein expression of said anti-toxin protein encoded by said second nucleic acid molecule is induced when said biosensor and said cellular metabolite form a complex and bind to said inducible first promoter; and d. a second nucleic acid molecule encoding a protein that is toxic for cell growth and/or survival, wherein the amino acid sequence of said protein has at least 80% sequence identity to a sequence selected from the group consisting of SEQ ID No.: 3, 36, 40 and 44, wherein said second nucleic acid molecule comprises a coding sequence operably linked to a promoter; wherein expression of said protein is prevented when said biosensor and said cellular metabolite form a complex and bind to said promoter; whereby arrest of growth and /or death of said cell due to an absence of complex formation does not depend on externally supplied growth inhibitor or growth retardant, and wherein said metabolite has a high fitness cost of production selected from among ≥ 5 %, ≥10%, ≥15%, ≥20%, and ≥25% measured relative to the growth rate of a reference microbial cell where production is inactivated.