Of 33 filamentous fungi, representing five taxonomic subdivisions, 3 1 were able to grow on heatkilled Bacillus subtilis cells as sole C, N and P source. Two types of decomposition were observed : cytolysis, in which the bacterial cytoplasm was rapidly degraded, leaving apparently empty cell walls, and bacteriolysis, in which the entire bacterial cell gradually disintegrated. Supernatants of cultures in which the latter type of attack occurred contained enzymes capable of dissolving bacterial cell walls. Most of these enzymes were glycosidases with pH optima of 2.0-3.9. Two were peptidases and/or amidases with pH optima of 7-8-8.3.

___The basidiomycete Schizophyhm commune produces an extracellular bacteriolytic enzyme when grown on heatkilled cells of Bacillus subtilis as sole C , N and P source. The enzyme catalyses the dissolution of isolated B. subtilis cell walls at an optimum pH of 3.2-3-4, releasing muramyl reducing groups, which indicates that it is a muramidase. Although low levels of enzyme activity are present when the fungus is grown in the absence of bacteria, full enzyme production appears to be induced by bacterial cells and repressed by glucose. Whole bacteria are not lysed by the enzyme at pH 3.3, but are rendered osmotically fragile, and lyse when the pH is raised to 7 or higher. The muramidase is effective against several Gram-positive bacteria but did not lyse any of the Gramnegative species tested.

Growth of Fusarium oxysporum on heat-killed Bacillus subtifis cells was accompanied by the loss of bacterial cytoplasmic contents, and this 'cytolysis' could be catalysed in heat-treated bacteria by the fungal culture fluids. In electron micrographs the bacterial walls appeared undamaged, and the absence of wall-lytic enzymes was confirmed by use of isolated bacterial walls as substrate. Appearance of cytolytic activity in cultures was paralleled by the production of proteolytic activity in the cultures. Proteolysis and cytolysis had similar pH optima at 8.8-9-0. Cultures grown on casein, but not glucose, produced high cytolytic activity. Rapid cytolysis occurred when heattreated B. subtifis cells were incubated with trypsin, subtilisin or pronase E. Viable bacteria, however, were not attacked, either by concentrated culture fluids or by the commercial protease preparations.

Currently used methods for the culture of mycobacteria from contaminated material were found to be unsatisfactory in an investigation of a possible environmental source of Mycobacterium avium-intracellulare-scrofulaceum (MAIS) infection in a New Zealand deer farm. Different combinations of established procedures were investigated using soil spiked with a laboratory strain of M. avium. The most successful combination involved mixing the soil in nutrient broth (pH 8.0) containing Tween 80, incubating at 37 degrees C for 1 h to germinate sporing contaminants, treatment for 24 h with 1% cetylpyridinium chloride, followed by washing and culture on Lowenstein-Jensen slopes and incubation at 37 degrees C and 42 degrees C in approximately 5% CO2 atmosphere. This procedure allowed good recovery of M. avium while successfully inhibiting saprophytic mycobacteria and other soil organisms, and was chosen to process the deer farm samples. No mycobacteria resembling the deer strains were found in these samples.