The microbiology of spent mushroom compost and its dust.

Microorganisms in spent steamed mushroom compost and its dust were enumerated, and identified. Some phase II (indoor composting) compost samples were also examined. Steaming of spent compost resulted in a 70-76% reduction in microbial numbers. Total counts made with compost fusion agar were approximately two logs greater than those for nutrient agar. The most common bacterial isolate was Bacillus licheniformis. The most common actinomycete isolates were Streptomyces diastaticus and Thermoactinomyces vulgaris. Other actinomycete isolates included Streptomyces albus, Streptomyces griseus, Thermoactinomyces thalpophilis, Thermomonospora chromogena, and Thermomonospora fusca. The most common fungal isolates were Aspergillus fumigatus and Humicola grisea var. thermoidea. Other fungal isolates included Aspergillus flavus, Aspergillus nidulans, Aspergillus terreus, Aspergillus versicolor group. Chrysosporium luteum, Mucor spp., Nigrospora spp., Oidiodendron spp., Paecilomyces spp., Penicillium chrysogenum, Penicillum expansum, Trichoderma viride, and Trichurus spp.

Microbial aerosols and actinomycetes in etiological considerations of mushroom workers' lungs.

Spent steamed compost, phase II compost, and dust emanating from spent compost during dumping of stationary-bed mushroom houses were examined bacteriologically. The total count for spent compost was 16 X 10(8) microorganisms per g. The total count for dust was 333 microorganisms per liter of air. Actinomycetes belonging to the genus Streptomyces often constituted 90% or more of isolates from dust, whereas mold spores constituted approximately 5%. Dust weight averaged 3.4 mg/liter of air and contained approximately 33% inanimate and 67% animate (microbial) particles. Spent compost and casing contained approximately 60% moisture; the average pH of compost was 6.93, and that of casing was 7.70. Ouchterlony precipitin results with antisera from workers afflicted with either farmer's or mushroom worker's lung were positive for Bacillus licheniformis, Micropolyspora faeni, Thermoactinomyces vulgaris, Aspergillus fumigatus, Humicola grisea var. thermoidea, spent compost, and phase II compost. Their usefulness in determining the etiology of this and related forms of allergic alveolitis is questioned and discussed. The relationship of dust particle size; microbial species, prevalence and antigenicity; and compost antigenicity to the etiology of mushroom worker's lung is discussed. The microbial ecology of mushroom compost and moldy hay associated with farmer's lung is compared.

T1 bacteriophage as an indicator for decontamination of laminar-flow biological safety cabinets.

Type 1 coliphage dried onto a glass surface was used as an indicator to monitor decontamination of biological safety cabinets. When desiccated virus was treated with formaldehyde vapor (5,000 or 10,000 ppm) adjusted to 70 to 90% relative humidity immediately before testing, viral inactivation was slow for the first 50 min but then accelerated, being complete in the next 10 min. However, when virus was incubated in an atmosphere containing 70% humidity for 1 h before formaldehyde was added, inactivation was complete within 3 min, indicating that careful attention must be paid to relative humidity in decontamination of safety cabinets.

Rate of Listeria monocytogenes shedding from frogs.

Leopard frogs (Rana pipiens) were orally inoculated with Listeria monocytogenes. Most listeriae were shed 3-6 days after inoculation. The evidence indicated that the listeriae did not multiply in frogs and were unable to become established in the gastrointestinal tract.

Contamination of sputum induction equipment during patient usage.

Sputum induction equipment was evaluated for its capacity to become contaminated by patients harboring Mycobacterium tuberculosis. The mouthpiece, goose-neck, and 10% NaCl solution were found capable of being contaminated by tuberculous patients. Two per cent glutaraldehyde was shown to be an effective means of decontamination. This study indicates that the entire induction apparatus must be cleaned and decontaminated between patients.