Exploring the Bioactive Secondary Metabolites of Two Argentine Trichoderma afroharzianum Strains

Abstract

<i>Trichoderma</i> spp. produce diverse secondary metabolites with biological activity. This study explored the antimicrobial, antibiofilm, antioxidant, and cytotoxic properties of metabolites from two native <i>Trichoderma</i> strains, 10BR1 and UEPA AR12, isolated from rhizospheric soils. Organic extracts from both strains demonstrated broad-spectrum antimicrobial activity, inhibiting Gram-positive and Gram-negative bacteria, as well as various <i>Candida</i> species, with notable efficacy against <i>Staphylococcus aureus</i> (MICs: 15.6-31.25 µg/mL). The extracts also showed antibiofilm activity, with UEPA AR12 exhibiting the highest inhibition against <i>Escherichia coli</i> (81.8%), <i>Enterococcus faecalis</i> (92.8%), <i>Candida albicans</i> (87.9%), and <i>Candida parapsilosis</i> (89.3%). Antioxidant activity, assessed via DPPH assay, revealed a dose-dependent radical scavenging effect (12.88% to 39.67% at 7.8-1000 µg/mL). Cytotoxicity assays indicated that UEPA AR12 extracts were more cytotoxic (IC₅₀: 202.5-234.3 µg/mL) than 10BR1 (IC₅₀: 368.7-602.1 µg/mL) in non-tumor cells, with similar trends in tumor cells (Huh7). HPLC/MS analysis identified 21 metabolites in the extracts. Genomic analyses, supported by <i>rpb2</i> gene and phylogenetic clustering, confirmed that both strains were <i>T. afroharzianum</i>. FUNGISMASH revealed multiple biosynthetic gene clusters, predominantly Type I polyketide synthase (T1PKS). Additionally, targeted genomic analyses did not detect mycotoxin-related genes. These findings highlight the antimicrobial, antibiofilm, and antioxidant potentials of these strains, positioning them as sources of bioactive metabolites for pharmaceutical applications.