ASW, 20 g l−" agar. Strains which remained sterile were
further cultivated using the ` balsa broth shake culture
technique ' (Hyde, Farrant & Jones 1987).
Cultures from which secondary metabolites were isolated
are being deposited in DSMZ (Braunschweig). Others are in
the collections of the Technical University of Braunschweig
and the University of Bonn.
Biological activity
Culture extracts
Fungal isolates were cultivated on 2±4 of the following media:
solid media I and II with ASW, solid medium I without ASW,
liquid medium I with ASW at room temperature. Liquid
cultures were shaken on a rotary shaker at 65 rpm for 14 days
at room temperature (RTC20°). Cultures were homogenized
using an Ika Ultra-Turrax T 25 at 8000 rpm for 2 min
following the addition of 50 ml water to the solid cultures.
Resultant mixtures were extracted with ethyl acetate
(3¬50 ml), the organic fractions combined and the solvent
removed at reduced pressure and 30°. For agar diffusion
assays and thin-layer chromatography, 5 mg residue were
redissolved in 1 ml of acetone}methanol (1 :1; v}v).
For the remaining tests, fungal cultures were extracted as
above with ethyl acetate (EtOAc) followed by n-butanol. The
solvent was removed at reduced pressure at 30°; 0±5 mg of
each resulting extract was dissolved in 250 ll dimethylsulphoxide
(DMSO) to yield sample solutions.