S.A. Hutchinson

Identification and biological effects of volatile metabolites from cultures of Trichoderma harzianum

Gases from cultures of a strain of Trichoderma harzianum Rifai inhibit growth and sporulation of Aspergillus niger and of Pestalotia rhododendri , and the coloration and rate of elongation of seedlings of Lactuca sativa var. sativa . The effects can be attributed to the amounts of carbon dioxide and ethanol formed by T. harzianum in the test conditions. Strains of Bacillus subtilis, Klebsiella aerogenes, Pseudomonas pyocyaneus, Staphylococcus aureus and Sarcina lutea were not inhibited by the culture gases.

Differences between the biological effects of culture gases from several species of Trichoderma

The differences in the amount of inhibition of growth of a range of assay fungi by gaseous metabolites from different species and strains of Trichodertna could be accounted for by differences in the rate of production of CO 2 in the test conditions. Differences in concentrations of acetaldehyde and of ethanol could also contribute to some of the effects. No other metabolites were found in sufficient gaseous concentrations to affect the results; this does not discount the possibility of unidentified metabolites contributing to some extent to the situations examined, or of small changes in the environment producing appreciable differences in the proportion and effects of constituents of the culture gas mixtures.

Biological activity of volatile metabolites from cultures of Fomes scutellatus.

In specified test conditions gases from cultures of Forms scutellatus (Schw.) Cooke inhibited the germination and growth of lettuce seedlings after diffusion through air, or through layers of peat, sand or peralite. They had no visible effect on 8 species of bacteria and only very slight effects on the growth of Aspergillus niger . The concentration of gaseous HCN produced by the cultures could account for the effects observed.

Analysis of wood-decaying ability of monokaryons and dikaryons of Serpula lacrymans

The wood-decaying abilities of 40 monokaryons of Serpula lacrymans have been compared with those of 138 dikaryons synthesized from them. This ability was less than in either of the component monokaryons in 57% of dikaryons, intermediate in 33% and greater in 10%. The character is controlled by a relatively simple polygenic system. One monokaryon introduced an unexplained genetic interaction; otherwise there was no evidence of dominance.

Some effects of volatile fungal metabolites on the gametophytes of Pteridium aquilinum

The growth of gametophytes of Pteridium aquilinum (L.) Kuhn in pure culture was stimulated by volatile metabolites from cultures of Zygorhynchus moelleri, Rhizopus sexualis, R. stolonifer ( + ) and ( − ), Absidia glauca ( + ) and ( − ), Achlya sp., Aspergillus niger, Botrytis cinere, Cladosporium herbarum, Colletotrichum linde-muthianum, Tilachlidium nigrum, Verticillium sp. It was inhibited by volatile metabolites from cultures of Saccharomvces cerevisiae and Schizosaccharomyces octosporus . Those from cultures of Agaricus campestris had no significant effect in the conditions tested.

Range of wood-decaying ability of different isolates of Serpula lacrimans

The rates of loss of dry weight, and of cross-grain breaking strength, of wood of Pinus sylvestris and some other tree species, were measured during decay by different isolates of Serpula lacrimans (Wulf. ex Fr.) Schrot. Some strains caused losses up to four times greater than others in standard controlled conditions.

Some effects of atmospheric humidity on the growth of Serpula lacrimans

Blocks of seasoned sapwood of Pinus sylvestris were infested with Serpuda lacrimans ([Wulf.] Fr.) Schroeter, then held at 20°C in an apparatus in which the ends of the blocks were exposed to atmospheres of known r.h., while the centre of the block was supplied with unlimited water. In these conditions the fungus grew out from the wood for substantial distance over a non-nutritive surface at humidities between 100 and 95%. It grew only slightly at 90% r.h. and not at all at humidities of 82% and below.