Bioactive and structural metabolites of Pseudomonas and Burkholderia species causal agents of cultivated mushrooms diseases

A review. Pseudomonas tolaasii, P. reactans and Burkholderia gladioli pv. agaricicola, are responsible of diseases on some species of cultivated mushrooms. The main bioactive metabolites produced by both Pseudomonas strains are the lipodepsipeptides (LDPs) tolaasin I and II and the so called White Line Inducing Principle (WLIP), resp., LDPs which have been extensively studied for their role in the disease process and for their biol. properties. In particular, their antimicrobial activity and the alteration of biol. and model membranes (red blood cell and liposomes) was established. In the case of tolaasin I interaction with membranes was also related to the tridimensional structure in soln. as detd. by NMR combined with mol. dynamic calcn. techniques. Recently, five news minor tolaasins, tolaasins A-E, were isolated from the culture filtrates of P. tolaasii and their chem. structure was detd. by extensive use of NMR and MS spectroscopy. Furthermore, their antimicrobial activity was evaluated on target micro-organisms (fungi-including the cultivated mushrooms Agaricus bisporus, Lentinus edodes, and Pleurotus spp.-chromista, yeast and bacteria). The Gram pos. bacteria resulted the most sensible and a significant structure-activity relationships was apparent. The isolation and structure detn. of bioactive metabolites produced by B. gladioli pv. agaricicola are still in progress but preliminary results indicate their peptide nature. Furthermore, the exopolysaccharide (EPS) from the culture filtrates of B. gladioli pv. agaricicola, as well as the O-chain and lipid A, from the lipo-polysaccharide (LPS) of the three bacteria, were isolated and the structures detd.