A new isocoumarin derivative from endophytic fungus Pezicula neosporulosa VDB39 from Vaccinium dunalianum.

Four isocoumarin derivatives (1-4) and five phenols (5-9) were obtained from the endophytic fungus Pezicula neosporulosa VDB39, which was isolated from the branches of Vaccinium dunalianum Wight (Ericaceae). Compound 1 is a new derivative of isocoumarin. The structures were elucidated by spectroscopic methods. Single X-ray crystallography confirmed the absolute configuration of compound 1. Additionally, the antiphytopathogenic fungi activity of isocoumarin derivatives (1-4) was evaluated.

The usnic acid derivative peziculone targets cell walls of Gram-positive bacteria revealed by high-throughput CRISPRi-seq analysis.

Usnic acid, a representative dibenzofuran metabolite, is known to have antimicrobial properties. However, despite considerable interest as an antimicrobial agent, the mechanism by which usnic acid and its derivatives exert their action is not fully characterized. This article describes the synthesis of peziculone, a 5:1 equilibrium mixture of two inseparable usnic acid derivatives: peziculone A and peziculone B. The antibacterial activity of peziculone against several Gram-positive bacterial pathogens was found to be significantly better compared with usnic acid. Clustered regularly interspaced short palindromic repeats interference sequencing analysis and membrane fluorescent staining were used to demonstrate that peziculone destabilizes the cell walls of Gram-positive bacteria. Additionally, peziculone 2.5 and 3.5 µg/mL impaired cell surface appendages and biofilm formation by Staphylococcus aureus. Taken together, these data demonstrate that peziculone, a derivative compound of usnic acid, has significant antimicrobial activity against Gram-positive bacteria by targeting the cell walls; this provides a platform for development of novel antibacterial drugs.

Taxonomy of Arthrinium minutisporum sp. nov., Pezicula neosporulosa, and Acrocalymma pterocarpi: New Records from Soil in Korea.

The strains 17E-042, 17E-039, and NC13-171 belong to Ascomycota and were isolated from soil collected from Sancheong-gun and Yeongam-gun, Korea. The strain 17E-042 produced white mycelial colonies that developed a sienna color with a round margin on potato dextrose agar (PDA), and the reverse side developed a light sienna color. Morphologically, this strain was similar to the strains of Arthrinium phragmites and A. hydei, but the shorter conidial size of the newly identified strain (17E-042) was distinct. The strain 17E-039 produced macroconidia that were pale yellow to orange-brown, elongated-ellipsoid to oblong, round at both ends, primarily straight but sometimes slightly curved, 0-septate, thin-walled, and filled with numerous droplets, having diameters of 20.4-34.3 × 8.0-12.0 µm. And the strain NC13-171 formed hyaline to light brown chlamydospores, solitary or in a chain. Multigene phylogenetic analyses were conducted using sequence data obtained from internal transcribed spacer (ITS) regions, 28S rDNA large subunit (LSU), ß-tubulin (TUB2), translation elongation factor 1-alpha (TEF1-α), and RNA polymerase II large subunit (RPB2) genes. The results of molecular phylogeny, the detailed descriptions and illustrations of each species strongly support our proposal that these strains from soil in Korea be designated as Arthrinium minutisporum sp. nov. and two new records of Pezicula neosporulosa and Acrocalymma pterocarpi.