[Detection of the quorum sensing signals in methanogenic archaea].

Methanosaeta harundinacea 6Ac displayed a cell-density dependent cell morphology transition between short rods (3 microm - 5 microm) and filaments ( >200 microm), implying a quorum sensing system in this archaeon. This study aimed to confirm that cell morphology related quorum sensing exists in Methanosaeta harundinacea. By using the bioassay of Agrobacterium tumefaciens NTL4, we determined the presence of acyl homoserine lactones (AHLs) in the spent cultures of Methanosaeta harundinacea 6Ac and other three methanogens. A chemical synthetic AHL, N-(beta-Ketooctanoyl)-L-homoserine lactone was added into the culture of short rods to detect the morphology change. We determined that AHLs were produced by Methanosaeta harundinacea, Methanosarcina mazei, Methanothermobacter thermautotrophicus and Methanobacterium formicicum. Addition of N-(beta-Ketooctanoyl)-L-homoserine lactone into the culture of Methanosaeta harundinacea 6Ac stimulated the formation of filamentous cells. This study indicates that AHL-based quorum sensing may be used by several species of methanogenic Archaea.