RESUMEN
Inhibitors of bacterial quorum sensing have been proposed as potentially novel therapeutics for the treatment of certain bacterial diseases. We recently reported a marine Halobacillus salinus isolate that secretes secondary metabolites capable of quenching quorum sensing phenotypes in several Gram-negative reporter strains. To investigate how widespread the production of such compounds may be in the marine bacterial environment, 332 Gram-positive isolates from diverse habitats were tested for their ability to interfere with Vibrio harveyi bioluminescence, a cell signaling-regulated phenotype. Rapid assay methods were employed where environmental isolates were propagated alongside the reporter strain. "Actives" were defined as bacteria that interfered with bioluminescence without visible cell-killing effects (antibiotic activity). A total of 49 bacterial isolates interfered with bioluminescence production in the assays. Metabolite extracts were generated from cultures of the active isolates, and 28 reproduced the bioluminescence inhibition against V. harveyi. Of those 28, five extracts additionally inhibited violacein production by Chromobacterium violaceum. Chemical investigations revealed that phenethylamides and a cyclic dipeptide are two types of secondary metabolites responsible for the observed activities. The active bacterial isolates belonged primarily to either the genus Bacillus or Halobacillus. The results suggest that Gram-positive marine bacteria are worthy of further investigation for the discovery of quorum sensing antagonists.
Asunto(s)
Antibacterianos/farmacología , Organismos Acuáticos/química , Bacillaceae/química , Sedimentos Geológicos/microbiología , Invertebrados/microbiología , Percepción de Quorum/efectos de los fármacos , Vibrio/efectos de los fármacos , Animales , Antibacterianos/aislamiento & purificación , Bahamas , Secuencia de Bases , Chromobacterium/química , Análisis por Conglomerados , Cartilla de ADN/genética , Indoles/antagonistas & inhibidores , Proteínas Luminiscentes/metabolismo , Datos de Secuencia Molecular , New England , Filogenia , Puerto Rico , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADNRESUMEN
Chemical studies of a Bacillus endophyticus isolated from a Bahamian hypersaline microbial mat led to the isolation of bacillamides B and C, new tryptamide thiazole metabolites. Bioassay-guided fractionation using a HPLC-UV-MS bioassay technique enabled the detection of these trace fermentation products, and their total structures were elucidated by combined spectroscopic techniques.