The effect of space flight on the production of the antibiotic monorden on two types of agar media, T8 and PG, by Humicola fuscoatra WC5157 was examined on board the US Space Shuttle mission STS-77 in May 1996. Paired space-flight and ground control samples were prepared using identical hardware, protocol, media, and inoculum. Inoculation occurred simultaneously for both groups 2.5 h after launch. The flight and ground samples were allowed to grow for the entire 10-day mission in a dark, thermally controlled (22 degrees C) environment. Post-flight HPLC analysis of the flight and ground sample extracts indicated that the production of monorden by H. fuscoatra WC5157 in the flight samples was higher than in the ground samples in both agar media. In the T8 medium, the production of monorden in the flight and ground samples was 11.6 +/- 3.5 mu g and 8.9 +/- 1.1 mu g respectively (30% increase). In the PG medium, the production of monorden in the flight and ground samples was 23.8 +/- 3.3 mu g and 8.2 +/- 2.2 mu g respectively (190% increase). The production of monorden in the flight and ground control samples was confirmed by HPLC-MS analysis.