Lysis of Soil Fungi by Bacteria

A number of bacteria capable of lysing Fusarium oxysporum were isolated from soil. One of these, a strain of Bacillus cereus, was studied in detail. Living and dead fusarium mycelium as well as cell-wall preparations were digested by the bacterium. Chitin and the hyphae of a number of other fungi also served as carbon sources for the active organisms, but there was no lysis of species of Pythium, Streptomyces, Agrobacterium, or Pseudomonas. Lysis appeared to be associated with chitinase and laminarinase activity of B. cereus, but incubation of fungus mycelium with chitinase alone, or with chitinase in combination with laminarinase, proteases and cellulase, did not result in lysis. N-Acetylhexosamine appeared during the digestion. Evidence was obtained to suggest that lytic microorganisms could destroy fungal mycelium in sterile soil.