Frontiers in fungal biology最新文献

The growing demand for novel enzyme producers to meet industrial and environmental needs has driven interest in lignocellulose-degrading fungi. In this study, lignocellulolytic enzyme production capabilities of environmental fungal isolates collected from boreal coniferous and nemoral summer green deciduous forests were investigated, using Congo Red, ABTS, and Azure B as indicators of cellulolytic and ligninolytic enzyme productions. Through qualitative and quantitative assays, the study aimed to identify promising species for lignocellulose-degrading enzyme secretion and assess their potential for biotechnological applications. Primary screening tests showed intensive enzyme secretion by certain isolates, particularly white rot fungi identified as Trametes pubescens and Cerrena unicolor. These fungi exhibited high efficiency in degrading Congo Red and Azure B. The isolates achieved up to a 93.30% decrease in Congo Red induced color intensity and over 78% decolorization of Azure B within 168 hours. Within 336 hours, these fungi reached nearly 99% removal of Congo Red and up to 99.79% decolorization of Azure B. Enzyme activity analysis confirmed the lignin-degrading capabilities of T. pubescens, which exhibited laccase activity exceeding 208 U/mL. Furthermore, Fomitopsis pinicola showed the highest cellulose-degrading potential among the studied fungi, achieving cellulase activity over 107 U/L during Congo Red decolorization. Previously undescribed enzyme-producing species, such as Peniophora cinerea, Phacidium subcorticalis, and Cladosporium pseudocladosporioides, also demonstrated promising lignocellulolytic enzyme production potential, achieving up to 98.65% and 99.80% decolorization of Congo Red and Azure B, respectively. The study demonstrates novel candidates for efficient lignocellulolytic enzyme production with broad biotechnological applications such as biomass conversion, wastewater treatment, textile dye and other complex chemical removal, and environmental remediation.

The antimicrobial peptide (AMP) circularized bacteriocin enterocin AS-48 produced by Enterococcus sp. exhibits broad-spectrum antibacterial activity via dimer insertion into the plasma membrane to form membrane pore structures, compromising membrane integrity and leading to bactericidal activity. A specific alpha-helical region of enterocin AS-48 has been shown to be responsible for the membrane-penetrating activity of the peptide. The canon syn-enterocin peptide library, generated using rational design techniques to have ninety-five synthetic peptide variants from the truncated, linearized, membrane-interacting domain of enterocin AS-48, was screened against three clinically relevant fungal strains: Cryptococcus neoformans, Candida albicans, and Candida auris for potential antifungal activity. Twelve peptides exhibited antifungal activity against C. neoformans, and two peptides exhibited activity against C. albicans. The fourteen active antifungal peptides were minimally cytotoxic to an immortalized human keratinocyte cell line (HaCats). Four select peptides were identified with minimum inhibitory concentrations (MICs) below 8 µM against C. neoformans. In 36-hour cell growth tests with these fungicidal peptides, fungicidal peptide no. 32 displayed inhibitory properties comparable to the leading antifungal medication fluconazole against C. neoformans. Screening of peptide no. 32 against a deletion library of C. neoformans mutants revealed that the mechanism of action of peptide no. 32 may relate to multivesicular bodies (MVBs) or polysaccharide capsule targeting. These findings importantly demonstrate that naturally derived AMPs produced by bacteria can be sourced, engineered, and modified to exhibit potent antifungal activity. Our results will contribute to the development of broad treatment alternatives to fungal infections and lend themselves to direct implications for possible treatment options for C. neoformans infections.

Research on enhancing the production of lipids, particularly polyunsaturated fatty acids that are considered important for health, has focused on improvement of metabolism as well as heterologous expression of biosynthetic genes in the oleaginous fungus Aspergillus oryzae. To date, the productivity and production yield of free fatty acids have been enhanced by 10-fold to 90-fold via improvements in metabolism and optimization of culture conditions. Moreover, the productivity of ester-type fatty acids present in triacylglycerols could be enhanced via metabolic improvement. Culturing A. oryzae in a liquid medium supplemented with non-ionic surfactants could also lead to the effective release of free fatty acids from the cells. The current review highlights the advancements made in this field so far and discusses the future outlook for research on lipid production using A. oryzae. I hope the contents are useful for researchers in this field to consider the strategy of increasing production of various valuable metabolites as well as lipids in A. oryzae.

Colletotrichum is a globally significant genus of plant pathogens known for causing anthracnose across a diverse array of hosts. Notably, Colletotrichum graminicola is a pathogen affecting maize. Annually, the global economic impact of this pathogen reaches billions of US dollars. C. graminicola produces conidia that have a characteristic falcate shape and are dispersed by rain. Upon attachment to maize leaves, these conidia develop melanized appressoria to penetrate the leaf surface to initiate disease. Recent findings have emphasized the existence of an adhesive strip on only one side of C. graminicola conidia. This strip colocalizes with an actin array, playing a crucial role in facilitating attachment and germination. This asymmetrical adhesive was postulated to enhance spore dispersal by assuring that some conidia do not attach to their initial deposition site. The extent of this asymmetric adhesive phenotype in other Colletotrichum species remains unknown, raising questions about its conservation within the genus. This study reveals the ubiquitous presence of an asymmetric adhesive on the conidia across nine isolates of Colletotrichum, representing eight species. Morphological differences in conidium shape and adhesive distribution were observed. Significantly, Colletotrichum truncatum is unique from other observed species by exhibiting an adhesive strip on both sides of its conidium. Furthermore, in C. graminicola, we noted a simultaneous development of the actin array and detachment from its mother cell after spore development. We posit that the study of other Colletotrichum members holds promise in elucidating the evolutionary trajectory of this phenotype. Furthermore, these insights may prove instrumental in understanding spore dispersal dynamics across diverse hosts, shedding light on the intricate web of host specificity within the genus.

Introduction: The Food and Agricultural Organization (FAO) reported that numerous diseases can be traced back to the consumption of unsafe food contaminated with mycotoxins. Mycotoxins are secondary metabolites produced by toxigenic filamentous fungi. Mycotoxins reported to be of socio-economic concerns include aflatoxins, fumonisins, zearalenone, ochratoxin A, and deoxynivalenol. These mycotoxins are frequent contaminants of maize especially in the face of climate change and global food insecurity. South Africa is a leading exporter of maize in Africa, hence, it is crucial to evaluate exposure risks with respect to mycotoxin contamination of maize for consumers' safety.

Materials and method: In total, 752 post-harvest maize samples collected from silos over a 3-year period were analysed using liquid chromatography with tandem mass spectrometry (LC-MS/MS) for the occurrence of mycotoxins.

Results and discussion: The overall mean values for all the quantified mycotoxins were within the South Africa regulatory limit as well as the individual samples, apart from DON and FB mycotoxins with 5% and 1% samples, respectively, above the limit. Citrinin was quantified in South African commercial maize for the first time. The presence of major mycotoxins in South African commercial maize even within safety limits is of public health concern, hence, continuous monitoring and evaluation is recommended.

The filamentous fungus Stachybotrys chartarum is rich in meroterpenoid secondary metabolites, some of which carry o-dialdehyde moieties, which are readily derivatized to isoindolinones by addition of primary amines. The structural diversity of phenylspirodrimanes, in particular, is linked to a wide range of biological activities, making them ideal candidates for semi-synthetic modification. In this study, acetoxystachybotrydial acetate was reacted with l-tryptophan and tryptamine, resulting in the detection of both regiospecific isomeric structures - a rare and significant finding that enabled the examination of four novel reaction products. Besides their successful purification, a detailed report on their isomer-specific behavior with regard to chromatographic retention, UV-spectral specificities, nuclear magnetic resonances, and mass spectrometric fragmentation is given. Furthermore, a comprehensive insight into each compounds' unique effect within the tested biological assays is provided, which include cytotoxicity, genotoxicity, their biological activity against serine proteases of the blood coagulation cascade, and in vitro hepatic metabolism, always in comparison to the non-derivatized substance. Ultimately, each isomer can be distinguished already during the purification process, which extends to the biological assays where we present one less cytotoxic, faster metabolized, and more active regio-isomeric phenylspirodrimane-derivative.

The application of microorganisms as bio-control agents against arthropod populations is a need in many countries, especially in tropical, subtropical, and neotropical endemic areas. Several arthropod species became agricultural pests of paramount economic significance, and many methods have been developed for field and urban applications to prevent their, the most common being the application of chemical insecticides. However, the indiscriminate treatment based upon those substances acted as a selective pressure for upcoming resistant phenotype populations. As alternative tools, microorganisms have been prospected as complementary tools for pest and vectorial control, once they act in a more specific pattern against target organisms than chemicals. They are considered environmentally friendly since they have considerably less off-target effects. Entomopathogenic fungi are organisms capable of exerting pathogenesis in many vector species, thus becoming potential tools for biological management. The entomopathogenic fungi Metarhizium sp. have been investigated as a microbiological agent for the control of populations of insects in tropical regions. However, the development of entomopathogenic fungi as control tools depends on physiological studies regarding aspects such as mechanisms of pathogenicity, secreted enzymes, viability, and host-pathogen aspects. The following review briefly narrates current aspects of entomopathogenic fungi, such as physiology, cellular characteristics, host-pathogen interactions, and its previous applications against different insect orders with medical and economic importance. Approaches integrating new isolation, prospection, characterization, delivery strategies, formulations, and molecular and genetic tools will be decisive to elucidate the molecular mechanisms of EPFs and to develop more sustainable alternative pesticides.

[This corrects the article DOI: 10.3389/ffunb.2024.1451455.].