Isolation and screening of fungal species isolated from Brazilian cerrado soil for antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Streptococcus pyogenes and Listeria monocytogenes

Objective. - To study the antimicrobial activity of fungi isolated from Brazilian cerrado soil. Material and methods. - A total of 200 fungal strains were isolated from soil samples collected from Serra do Cipo National Park in Brazil. Antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhimurium, Streptococcus pyogenes and Listeria monocytogenes was screened. Results. - Around 67% of the extracts showed activity against at least one of the tested bacteria. Thirteen isolates, selected as the most common species found in the studied soil samples (over 50% of all isolates), were microscopically identified as Chaetomium cupreum, Curvularia senegalensis, Fusarium oxysporum, Penicillium citrinum, Penicillium janthinellum, Penicillium paxilli, Penicillium sclerotiorum, Penicillium simplicissimum, Penicillium waksmanii, Rhizopus stolonifer, Syncephalastrum racemosum, Trichoderma koningii and Trichoderma reesei. Large scale experiment proved positive antibacterial results for Penicillium sclerotiorum and Penicillium simplicissimum, since bioactive metabolites (sclerotiorin, isochromophilone VI, pencolide and penicillic acid) were recovered from their fermentation in preparative scale. Conclusion. - Cerrado soil fungi constitute another important source of antibiotics producing micro-organisms that can be further exploited as source of lead compounds for anti-infective agents industry. (C) 2008 Elsevier Masson SAS. All rights reserved.