Abstract
Postharvest diseases represent a critical challenge for global agriculture, resulting in substantial economic losses and threatening worldwide food security. Species of the genus Colletotrichum stand out among the main phytopathogens for being responsible for up to 40% of postharvest losses in various crops, including Capsicum species. This study evaluated the antifungal activity of two Streptomyces strains isolated from Amazonian sediments against different Colletotrichum species, with a focus on C. scovillei, the causal agent of anthracnose in Capsicum chinense fruits. Multilocus phylogenetic analyses indicated that strain APUR 32.5 possibly represents a new species, while MPUR 40.3 was identified as Streptomyces murinus. Both strains exhibited in vitro antifungal activity against seven Colletotrichum species, with inhibition percentages ranging from 56.3% to 88.6%. In fruit bioassays, S. murinus MPUR 40.3 reduced the incidence of anthracnose by 95%, while Streptomyces sp. APUR 32.5 achieved a 39.25% reduction. Scanning electron microscopy revealed complementary mechanisms of antifungal action, with MPUR 40.3 acting during the early infection stages through germination tube lysis, while APUR 32.5 targeted established mycelial structures through hyphal degradation. Additionally, both strains demonstrated plant growth-promoting capacity and exhibited biotechnologically relevant characteristics, including production of hydrolytic enzymes, siderophores, and phosphate solubilization ability. These results highlight the biotechnological promise of these Amazonian isolates as multifunctional agents for the sustainable management of anthracnose in Capsicum peppers.