Acta Pharm. 55 (2005) 365-376

IVAN KOSALEC^* and STJEPAN PEPELJNJAK

ikosalec@pharma.hr

Department of Microbiology, Faculty of Pharmacy and Biochemistry, University of Zagreb, Zagreb, Croatia

Clinical isolates of fifty strains of A. fumigatus and 30 strains of A. flavus from immmunocompromised patients from the hematological unit were analyzed for mycotoxin production and compared with the same number of environmental isolates (from soil, compost, and air). Only 9 (18%) strains of A. fumigatus produced gliotoxin in a mean concentration 2.22 mg mL^-1 (range 0.5-5 mg mL^-1). Aflatoxin B₁ was detected in 7 (23%) isolates (range from 0.02 to 1.2 mg L^-1) and aflatoxin G₁ in one (3%) of clinical A. flavus isolates (0.12 mg L^-1). In the group of environmental isolates, 11 (37%) were positive for aflatoxin B₁ production (range from 0.02 to 1.2 mg L^-1) and one for aflatoxin G₁ (0.02 mg L^-1). Bioautoantibiogram ("bioassay in situ") on TLC plates against Bacillus subtilis NCTC 8236 showed that only gliotoxin-producing strains have bactericidal activity of R_f values corresponding to gliotoxin. The secondary-metabolite profiles of clinical and environmental A. fumigatus and A. flavus isolates were homogenous, except for gliotoxin production, which was detected only in the group of clinical isolates of A. fumigatus (18%).

Keywords: Aspergillus, A. fumigatus, A. flavus, gliotoxin, aflatoxin, mycotoxin, in vitro production, secondary metabolites, moulds