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UBC Theses and Dissertations

Biological control of olive green mold in the cultivation of Agaricus bisporus Tautorus, Thomas Edward


The Canadian mushroom industry is experiencing the same problems as are encountered worldwide - attacks of diseases and pests (lngratta, 1980). Successful methods to control the damaging weed mold -Chaetomium olivaceum (Olive green mold) in mushroom beds are presently not known. This thesis investigation attempted to control C. olivaceum by biological means. A thermophilic Bacillus sp (resembling B. coagu-lans - resistant to 0.02% sodium azide, acidophilic) which showed dramatic activity against C. olivaceum on TSY (Trypticase soy agar + 0.1% Yeast extract) agar plates was isolated from commercial mushroom compost (phase I). When inoculated into conventional and hydroponic mushroom beds, the Bacillus not only provided a significant degree of protection from C. olivaceum but also increased yields of Agaricus bisporus. This is the first isolation of a microorganism inhibitory to Olive green mold. The Bacillus was shown to produce an extremely potent and stable antibiotic (named Chaetomacin) effective over a wide range of both pH (2-10) and temperature (-15°C to 150°C). Chaetomacin is soluble in most polar solvents and insoluble in non-polar solvents. This antibiotic produced at mesophilic temperatures is also active against other Bacillus species and various eukaryotes - but demonstrates no activity against Cram negative organisms or Gram positive cocci. Final purification of Chaetomacin was accomplished through thin layer chromatography on Silica gel analytical plates. Amino acid analysis revealed the antibiotic to be a peptide, acidic in nature. Examination of the literature reveals no other previously isolated antibiotics which are identical to Chaetomacin.

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