Methylobacterium extorquens AM1 produces a novel type of acyl‐homoserine lactone with a double unsaturated side chain under methylotrophic growth conditions

Acyl‐homoserine lactones (acyl‐HSLs) have emerged as important regulatory molecules for many gram‐negative bacteria. We have found that Methylobacterium extorquens AM1, a member of the pink‐pigmented facultative methylotrophs commonly present on plant surfaces, produces several acyl‐HSLs depending upon the carbon source. A novel HSL was discovered with a double unsaturated carbon chain ( N ‐(tetradecenoyl)) (C14:2) and characterized by MS and proton NMR. This long‐chain acyl‐HSL is synthesized by MlaI that also directs synthesis of C14:1‐HSL. The Alphaproteobacterium also produces N ‐hexanoyl‐HSL (C6‐HSL) and N ‐octanoyl‐HSL (C8‐HSL) via Msa I.