WLIP, a lipodepsipeptide of Pseudomonas 'reactans', as inhibitor of the symptoms of the brown blotch disease of Agaricus bisporus

A cell-free crude extract containing the white line inducing principle (WLI P), a lipodepsipeptide produced by Pseudomonas 'reactans', could inhibit br owning of mushrooms caused by Pseudomonas tolaasii. Mushrooms inoculated wi th Ps, tolaasii at concentrations of 2.7 x 10(6) cfu ml(-1) or higher showe d the symptoms of the disease after 2 d of incubation. Mushroom caps treate d with various concentrations of a crude WLIP preparation, and later inocul ated with bacterial concentrations higher than the threshold value, did not develop the symptoms of the disease. One milligram of a crude WLIP prepara tion could block 50% of the symptoms caused by 1.2 x 10(7) cfu. The inhibit ion of browning was effective when incubating at low temperatures for 4 d. A suspension containing 1.6 mg ml(-1) of pure WLIP was also able to inhibit the symptoms of brown blotch disease induced by 7.6 x 10(6) cfu ml(-1) of Ps, tolaasii.