Molecular basis of antifungal toxin production by fluorescent Pseudomonas sp. strain EM 85 - a biological control agent.

摘要

A fluorescent Pseudomonas sp. (strain EM 85) was found to inhibit growth of many soil-borne plant pathogenic fungi and effectively control fungal diseases. The genetics governing this character was probed by mutagenesis followed by a functional complementation analysis after construction of a genomic library of the wild-type strain using the cosmid vector pLAFR 1. A cosmid clone, pANF 17 was able to complement the antifungal toxin production in a defective mutant. The chromosomal origin of the DNAfragment in the cosmid clone was confirmed by a Southern blot. Sub-clones of the three EcoRI fragments from pANF 17, however, failed in the complementation test. The complementing cosmid was stably maintained and expressed in the defective mutant under laboratory plate assay and in vivo conditions as evidenced by the extraction and detection of the toxin and biological control experiment.