Fungal growth and stimulation by thiosulphate under oligocarbotrophic conditions

A range of fungi grew in a liquid medium lacking added carbon, apparently by scavenging carbon from the medium and laboratory atmosphere. Trichoderma harzianum also grew on a carbon-free medium which was solidified by adding a pluronic polyol. This fungus formed mycelial ‘gossamers’ in a low-carbon medium (50 μg C ml⁻¹), i.e. fine sheets of hyphae showing numerous anastomoses. It also oxidized elemental sulphur in a synthetic soil amended with low concentrations of glucose (10–100 μg C g⁻¹). Thiosulphate stimulated the biomass yield of the fungus in carbon-free liquid media and increased colony radial growth over the first 24 h when grown on an agar medium containing small amounts of carbon. The relevance of oligocarbotrophy and possible chemolithoheterotrophic growth by fungi on thiosulphate to their ability to grow in carbon deficient soils is discussed.