A protein involved in fatty acid synthesis, said protein comprising one or more polypeptide chains, wherein said polypeptide chain(s) comprise (i) one or more subunits comprising the amino acid sequences of SEQ ID NO: 1 (malonyl/palmitoyl transferase domain, MPT domain); SEQ ID NO: 2 (acetyl transferase domain, AT domain), and/or SEQ ID NO: 3 (ketoacyl synthase domain, KS domain); (ii) at least one amino acid substitution in the MPT domain at a position corresponding to R130 of the amino acid sequence of SEQ ID NO: 1; and/or at least one amino acid substitution in the AT domain at a position corresponding to 1306 of the amino acid sequence of SEQ ID NO: 2; and/or in the KS domain, an amino acid substitution in a position corresponding to G236 in combination with an amino acid substitution in a position corresponding to M237 and/or F265 of the amino acid sequence of SEQ ID NO: 3; wherein the amino acid sequence comprising the at least one amino acid substitution has at least 70%, or preferably at least 80% or 90% or 95% sequence identity to the respective amino acid sequence of SEQ ID NO: 1 and/or 2, and/or at least 90% or 95% sequence identity to the respective amino acid sequence of SEQ ID NO: 3, resulting in elevated overall production of short fatty acids, CoA esters of C 6 to C 12 short fatty acids, ethyl esters of C 6 to C 12 short fatty acids, esters of C 6 to C 12 short fatty acids with other metabolites, and/or enzyme bound C 6 to C 12 short fatty acids compared to the wild type protein(s) or the protein(s) without such amino acid substitution(s), provided that when the protein comprises the amino acid substitution G236S in the KS domain it comprises at least one additional amino acid substitution. said protein comprising one or more polypeptide chains, wherein said polypeptide chain(s) comprise (i) one or more subunits comprising the amino acid sequences of SEQ ID NO: 1 (malonyl/palmitoyl transferase domain, MPT domain); SEQ ID NO: 2 (acetyl transferase domain, AT domain), and/or SEQ ID NO: 3 (ketoacyl synthase domain, KS domain); (ii) at least one amino acid substitution in the MPT domain at a position corresponding to R130 of the amino acid sequence of SEQ ID NO: 1; and/or at least one amino acid substitution in the AT domain at a position corresponding to 1306 of the amino acid sequence of SEQ ID NO: 2; and/or in the KS domain, an amino acid substitution in a position corresponding to G236 in combination with an amino acid substitution in a position corresponding to M237 and/or F265 of the amino acid sequence of SEQ ID NO: 3; wherein the amino acid sequence comprising the at least one amino acid substitution has at least 70%, or preferably at least 80% or 90% or 95% sequence identity to the respective amino acid sequence of SEQ ID NO: 1 and/or 2, and/or at least 90% or 95% sequence identity to the respective amino acid sequence of SEQ ID NO: 3, (i) one or more subunits comprising the amino acid sequences of SEQ ID NO: 1 (malonyl/palmitoyl transferase domain, MPT domain); SEQ ID NO: 2 (acetyl transferase domain, AT domain), and/or SEQ ID NO: 3 (ketoacyl synthase domain, KS domain); SEQ ID NO: 1 (malonyl/palmitoyl transferase domain, MPT domain); SEQ ID NO: 2 (acetyl transferase domain, AT domain), and/or SEQ ID NO: 3 (ketoacyl synthase domain, KS domain); (ii) at least one amino acid substitution in the MPT domain at a position corresponding to R130 of the amino acid sequence of SEQ ID NO: 1; and/or at least one amino acid substitution in the AT domain at a position corresponding to 1306 of the amino acid sequence of SEQ ID NO: 2; and/or in the KS domain, an amino acid substitution in a position corresponding to G236 in combination with an amino acid substitution in a position corresponding to M237 and/or F265 of the amino acid sequence of SEQ ID NO: 3; wherein the amino acid sequence comprising the at least one amino acid substitution has at least 70%, or preferably at least 80% or 90% or 95% sequence identity to the respective amino acid sequence of SEQ ID NO: 1 and/or 2, and/or at least 90% or 95% sequence identity to the respective amino acid sequence of SEQ ID NO: 3, and/or at least one amino acid substitution in the AT domain at a position corresponding to 1306 of the amino acid sequence of SEQ ID NO: 2; and/or in the KS domain, an amino acid substitution in a position corresponding to G236 in combination with an amino acid substitution in a position corresponding to M237 and/or F265 of the amino acid sequence of SEQ ID NO: 3; wherein the amino acid sequence comprising the at least one amino acid substitution has at least 70%, or preferably at least 80% or 90% or 95% sequence identity to the respective amino acid sequence of SEQ ID NO: 1 and/or 2, and/or at least 90% or 95% sequence identity to the respective amino acid sequence of SEQ ID NO: 3, resulting in elevated overall production of short fatty acids, CoA esters of C 6 to C 12 short fatty acids, ethyl esters of C 6 to C 12 short fatty acids, esters of C 6 to C 12 short fatty acids with other metabolites, and/or enzyme bound C 6 to C 12 short fatty acids compared to the wild type protein(s) or the protein(s) without such amino acid substitution(s), provided that when the protein comprises the amino acid substitution G236S in the KS domain it comprises at least one additional amino acid substitution.