Beschreibung:
<jats:title>ABSTRACT</jats:title>
<jats:p>
Our study focused on a
<jats:italic>Mesorhizobium</jats:italic>
sp. that is phylogenetically affiliated by 16S rRNA gene sequence to other marine and saline bacteria of this genus. Liquid chromatography-mass spectrometry investigations of the extract obtained from solid-phase extraction of cultures of this bacterium indicated the presence of several
<jats:italic>N</jats:italic>
-acyl homoserine lactones (AHLs), with chain lengths of C
<jats:sub>10</jats:sub>
to C
<jats:sub>16</jats:sub>
. Chromatographic separation of the active bacterial extract yielded extraordinarily large amounts of two unprecedented acylated homoserine lactones, 5-
<jats:italic>cis</jats:italic>
-3-oxo-C
<jats:sub>12</jats:sub>
-homoserine lactone (5-
<jats:italic>cis</jats:italic>
-3-oxo-C
<jats:sub>12</jats:sub>
-HSL) (compound 1) and 5-
<jats:italic>cis</jats:italic>
-C
<jats:sub>12</jats:sub>
-HSL (compound 2). Quorum-sensing activity of compounds 1 and 2 was shown in two different biosensor systems [
<jats:italic>Escherichia coli</jats:italic>
MT102(pSB403) and
<jats:italic>Pseudomonas putida</jats:italic>
F117(pKR-C12)]. Furthermore, it was shown that both compounds can restore protease and pyoverdin production of an AHL-deficient
<jats:italic>Pseudomonas aeruginosa</jats:italic>
PAO1
<jats:italic>lasI rhlI</jats:italic>
double mutant, suggesting that these signal molecules maybe used for intergenus signaling. In conclusion, these data indicate that the quorum-sensing activity of compounds 1 and 2 is modulated by the chain length and functional groups of the acyl moiety. Additionally, compound 1 showed antibacterial and cytotoxic activities.
</jats:p>