Ascal ultrastructural study in Annulatascus hongkongensis sp. nov., a freshwater ascomycete

Biodiversity of endosymbiont fungi associated with a marine sponge Lamellodysidea herbacea and their potential as antioxidant producers

This study aims to isolate endosymbiontic fungi from the marine sponge Lamellodysidea herbacea and to explore their antioxidant potential. Marine-derived fungi, with their vast biodiversity, are considered a promising source of novel antioxidants which can replace synthetic ones. Marine sponges have previously reported bioactive properties that could ameliorate oxidative stress, particularly their associated fungi, producing high-frequency bioactive molecules (adaptogenic molecules) in response to stressors. 19 endosymbiont fungi associated with marine sponges were isolated, and their extracts were evaluated for their antioxidant capacities. Extract of an endosymbiont fungus, isolate SPG6, identified as Alternaria destruens, through surface electron microscopy (SEM) and ITS gene sequencing, showed broad range antioxidant activities (EC50 values) (free radical scavenging 32.54 mg L-1, Hydroxyl radical scavenging activity < 0.078 g L-1, total reducing power 0.114 g L-1, Chelating power 0.262 g L-1, H2O2 scavenging activity < 0.078 g L-1, and Superoxide radical scavenging activity > 5.0 g L-1). The extract of isolate SPG6 was fractioned and analyzed through GC-MS. Marine sponge-associated endosymbiont fungi are a rich source of antioxidant molecules.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03972-1.

A combinatorial approach of Monarda citriodora essential oil (MEO) and linalool vapors to control fruit rot of Citrus limon caused by a new pathogen, Aspergillus foetidus, and its underlying mode of action

AIMS

Citrus limon (lemon) is a widely cultivated citrus fruit. Significant postharvest losses due to fungi plague its production. Environmental and human health hazards have made the application of synthetic fungicides unsuitable. Despite the previous reports of antifungal activities of essential oil (EO) vapors, their synergistic combinations are understudied. Synergistic vapor combinations are advantageous due to less concentration of active components. This study aimed to isolate and identify postharvest fungal pathogens lemon and to evaluate the antifungal effects of synergistic Monarda citriodora EO (MEO)-constituent vapor combinations in vivo and in vitro.

METHODS AND RESULTS

Postharvest fungal pathogens of lemon (C. limon) were isolated from various infected samples. The most pathogenic isolate was identified through morphology and its ITS-based rRNA gene sequencing as Aspergillus foetidus (O4). This is the first report of A. foetidus as a postharvest pathogen of lemon. The minimum fungicidal concentrations (MFCs) of MEO vapors treatment against O4 were 1346.15 µL/L air. For carvacrol, hexanal, and linalool, MFC was same (96.16 µL/L air). Checkerboard assays demonstrated that 1/4 MFC of MEO (336.54 µL/L air) and 1/4 MFC of linalool (24.04 µL/L air) (M + L) were synergistic against O4. M + L vapors reduced the O4 growth on lemons during storage by 64% ± 1.50% and preserved their quality (low weight loss %, unchanged pH, increased ascorbic acid content). Propidium iodide staining, ergosterol content analysis, calcofluor white staining and chitin content analysis revealed the integrity loss of the O4 plasma membrane and cell wall. 2',7'-Dichlorofluorescin diacetate staining revealed accumulation of intracellular reactive oxygen species (ROS), and scanning electron microscopy (SEM) analysis exposed the M + L treated mycelia with malformations.

CONCLUSIONS

M + L vapors offer protection for lemons from A. foetidus and preserve their quality during storage.

Freshwater Sordariomycetes

Sordariomycetes is one of the largest classes of Ascomycota that comprises a highly diverse range of fungi mainly characterized by perithecial ascomata and inoperculate unitunicate asci. Freshwater Sordariomycetes play an important role in ecosystems and some of them have the potential to produce bioactive compounds. This study documents and reviews the freshwater Sordariomycetes, which is one of the largest and important groups of fungi in aquatic habitats. Based on evidence from DNA sequence data and morphology, we introduce a new order Distoseptisporales, two new families, viz. Ceratosphaeriaceae and Triadelphiaceae, three new genera, viz. Aquafiliformis, Dematiosporium and Neospadicoides, 47 new species, viz. Acrodictys fluminicola, Aquafiliformis lignicola, Aquapteridospora fusiformis, Arthrinium aquaticum, Ascosacculus fusiformis, Atractospora aquatica, Barbatosphaeria lignicola, Ceratosphaeria aquatica, C. lignicola, Chaetosphaeria aquatica, Ch. catenulata, Ch. guttulata, Ch. submersa, Codinaea yunnanensis, Conioscypha aquatica, C. submersa, Cordana aquatica, C. lignicola, Cosmospora aquatica, Cylindrotrichum submersum, Dematiosporium aquaticum, Dictyochaeta cangshanensis, D. ellipsoidea, D. lignicola, D. submersa, Distoseptispora appendiculata, D. lignicola, D. neorostrata, D. obclavata, Hypoxylon lignicola, Lepteutypa aquatica, Myrmecridium aquaticum, Neospadicoides aquatica, N. lignicola, N. yunnanensis, Ophioceras submersum, Peroneutypa lignicola, Phaeoisaria filiformis, Pseudostanjehughesia lignicola, Rhodoveronaea aquatica, Seiridium aquaticum, Sporidesmiella aquatica, Sporidesmium lageniforme, S. lignicola, Tainosphaeria lunata, T. obclavata, Wongia aquatica, two new combinations, viz. Acrodictys aquatica, Cylindrotrichum aquaticum, and 9 new records, viz. Chaetomium globosum, Chaetosphaeria cubensis, Ch. myriocarpa, Cordana abramovii, Co. terrestris, Cuspidatispora xiphiago, Sporidesmiella hyalosperma, Stachybotrys chartarum,S. chlorohalonata. A comprehensive classification of the freshwater Sordariomycetes is presented based on updated literature. Phylogenetic inferences based on DNA sequence analyses of a combined LSU, SSU, RPB2 and TEF1α dataset comprising species of freshwater Sordariomycetes are provided. Detailed information including their habitats distribution, diversity, holotype, specimens collected and classification are provided.