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Autoinducer-2 of the fire blight pathogen Erwinia amylovora and other plant-associated bacteria

Mohammadi, Mojtaba, Geider, Klaus
FEMS microbiology letters 2007 v.266 no.1 pp. 34-41
DNA, Erwinia amylovora, Erwinia pyrifoliae, Escherichia coli, Pantoea stewartii, Pectobacterium carotovorum subsp. atrosepticum, Pseudomonas syringae, Salmonella Typhimurium, Vibrio harveyi, bacteria, genes, mutants, pathogens, pathovars, polymerase chain reaction
Autoinducers are important for cellular communication of bacteria. The luxS gene has a central role in the synthesis of autoinducer-2 (AI-2). The gene was identified in a shotgun library of Erwinia amylovora and primers designed for PCR amplification from bacterial DNA. Supernatants of several Erwinia amylovora strains were assayed for AI-2 activity with a Vibrio harveyi mutant and were positive. Many other plant-associated bacteria also showed AI-2 activity such as Erwinia pyrifoliae and Erwinia tasmaniensis. The luxS genes of several bacteria were cloned, sequenced, and complemented Escherichia coli strain DH5α and a Salmonella typhimurium mutant, both defective in luxS, for synthesis of AI-2. Assays to detect AI-2 activity in culture supernatants of several Pseudomonas syringae pathovars failed, which may indicate the absence of AI-2 or synthesis of another type. Several reporter strains did not detect synthesis of an acyl homoserine lactone (AHL, AI-1) by Erwinia amylovora, but confirmed AHL-synthesis for Erwinia carotovora ssp. atroseptica and Pantoea stewartii.