Correlative metabologenomics of 110 fungi reveals metabolite-gene cluster pairs.

Natural products research increasingly applies -omics technologies to guide molecular discovery. While the combined analysis of genomic and metabolomic datasets has proved valuable for identifying natural products and their biosynthetic gene clusters (BGCs) in bacteria, this integrated approach lacks application to fungi. Because fungi are hyper-diverse and underexplored for new chemistry and bioactivities, we created a linked genomics-metabolomics dataset for 110 Ascomycetes, and optimized both gene cluster family (GCF) networking parameters and correlation-based scoring for pairing fungal natural products with their BGCs. Using a network of 3,007 GCFs (organized from 7,020 BGCs), we examined 25 known natural products originating from 16 known BGCs and observed statistically significant associations between 21 of these compounds and their validated BGCs. Furthermore, the scalable platform identified the BGC for the pestalamides, demystifying its biogenesis, and revealed more than 200 high-scoring natural product-GCF linkages to direct future discovery.

What was old is new again: Phenotypic screening of a unique fungal library yields pyridoxatin, a promising lead against extensively resistant Acinetobacter baumannii (AB5075).

Due to the emergence of resistance, the World Health Organization considers Gram-negative pathogen Acinetobacter baumannii a top priority for therapeutic development. Using this priority pathogen and a phenotypic, agar plate-based assay, a unique library of extracts from 2,500 diverse fungi was screened for antimicrobial activity against a highly virulent, drug-resistant strain of A. baumannii (AB5075). The most potent hit from this screen was an extract from the fungus Tolypocladium sp., which was found to produce pyridoxatin. Another active extract from the fungi Trichoderma deliquescens was characterized and yielded trichokonin VII and trichokonin VIII. Evaluation of pyridoxatin against A. baumannii (AB5075) in a broth microdilution assay revealed a minimum inhibitory concentration (MIC) of 38 µM, compared to the known antibiotic levofloxacin with MIC of 28 µM. Mass spectrometry, Marfey's analysis and nuclear magnetic resonance spectroscopy analyses confirmed the structures of trichokonins VII and VIII to be consistent with previous reports. In an in vivo Galleria mellonella model, pyridoxatin tested at 150 mg/kg exhibited minimal toxicity (90% survival) and promising antimicrobial efficacy (50% survival) after 5 days. Trichokonins VII and VIII tested at 150 mg/kg were toxic to G. mellonella, with 20% survival and 40% survival after 5 days, respectively. The findings of this project suggest that pyridoxatin may serve as a lead compound for the development of antimicrobials against A. baumannii. They also demonstrate the value of the phenotypic screening approach employed herein.

Sheptide A: an antimalarial cyclic pentapeptide from a fungal strain in the Herpotrichiellaceae.

As part of ongoing efforts to isolate biologically active fungal metabolites, a cyclic pentapeptide, sheptide A (1), was discovered from strain MSX53339 (Herpotrichiellaceae). The structure and sequence of 1 were determined primarily by analysis of 2D NMR and HRMS/MS data, while the absolute configuration was assigned using a modified version of Marfey's method. In an in vitro assay for antimalarial potency, 1 displayed a pEC50 value of 5.75 ± 0.49 against malaria-causing Plasmodium falciparum. Compound 1 was also tested in a counter screen for general cytotoxicity against human hepatocellular carcinoma (HepG2), yielding a pCC50 value of 5.01 ± 0.45 and indicating a selectivity factor of ~6. This makes 1 the third known cyclic pentapeptide biosynthesized by fungi with antimalarial activity.

Metabolomics-Guided Comparison of Pollen and Microalgae-Based Artificial Diets in Honey Bees.

Managed honey bee colonies used for crop pollination are fed artificial diets to offset nutritional deficiencies related to land-use intensification and climate change. In this study, we formulated novel microalgae diets using Chlorella vulgaris and Arthrospira platensis (spirulina) biomass and fed them to young adult honey bee workers. Diet-induced changes in bee metabolite profiles were studied relative to a natural pollen diet using liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) metabolomics. Untargeted analyses of pollen- and microalgae-fed bees revealed significant overlap, with 248 shared features determined by LC-MS and 87 shared features determined by GC-MS. Further metabolomic commonalities were evident upon subtraction of unique diet features. Twenty-five identified metabolites were influenced by diet, which included complex lipids, essential fatty acids, vitamins, and phytochemicals. The metabolomics results are useful to understand mechanisms underlying favorable growth performance as well as increased antioxidant and heat shock protein gene expression in bees fed the microalgae diets. We conclude that the tested microalgae have potential as sustainable feed additives and as a source of bee health-modulating natural products. Metabolomics-guided diet development could eventually help tailor feed interventions to achieve precision nutrition in honey bees and other livestock animals.

Polychlorinated cyclopentenes from a marine derived Periconia sp. (strain G1144).

Studies on an organic extract of a marine fungus, Periconia sp. (strain G1144), led to the isolation of three halogenated cyclopentenes along with the known and recently reported rhytidhyester D; a series of spectrometric and spectroscopic techniques were used to elucidate these structures. Interestingly, two of these compounds represent tri-halogenated cyclopentene derivatives, which have been observed only rarely from Nature. The relative and absolute configurations of the compounds were established via mass spectrometry (MS), nuclear magnetic resonance (NMR) spectroscopy, Mosher's esters method, optical rotation and GIAO NMR calculations, including correlation coefficient calculations and the use of both DP4+ and dJ DP4 analyses. Several of the isolated compounds were tested for activity in anti-parasitic, antimicrobial, quorum sensing inhibition, and cytotoxicity assays and were shown to be inactive.

Genomic Characterization of Parengyodontium torokii sp. nov., a Biofilm-Forming Fungus Isolated from Mars 2020 Assembly Facility.

A fungal strain (FJII-L10-SW-P1) was isolated from the Mars 2020 spacecraft assembly facility and exhibited biofilm formation on spacecraft-qualified Teflon surfaces. The reconstruction of a six-loci gene tree (ITS, LSU, SSU, RPB1 and RPB2, and TEF1) using multi-locus sequence typing (MLST) analyses of the strain FJII-L10-SW-P1 supported a close relationship to other known Parengyodontium album subclade 3 isolates while being phylogenetically distinct from subclade 1 strains. The zig-zag rachides morphology of the conidiogenous cells and spindle-shaped conidia were the distinct morphological characteristics of the P. album subclade 3 strains. The MLST data and morphological analysis supported the conclusion that the P. album subclade 3 strains could be classified as a new species of the genus Parengyodontium and placed in the family Cordycipitaceae. The name Parengyodontium torokii sp. nov. is proposed to accommodate the strain, with FJII-L10-SW-P1 as the holotype. The genome of the FJII-L10-SW-P1 strain was sequenced, annotated, and the secondary metabolite clusters were identified. Genes predicted to be responsible for biofilm formation and adhesion to surfaces were identified. Homology-based assignment of gene ontologies to the predicted proteome of P. torokii revealed the presence of gene clusters responsible for synthesizing several metabolic compounds, including a cytochalasin that was also verified using traditional metabolomic analysis.

Polyphasic Approach Utilized for the Identification of Two New Toxigenic Members of Penicillium Section Exilicaulis, P. krskae and P. silybi spp. nov.

Two new species, Penicillium krskae (isolated from the air as a lab contaminant in Tulln (Austria, EU)) and Penicillium silybi (isolated as an endophyte from asymptomatic milk thistle (Silybum marianum) stems from Josephine County (Oregon, USA)) are described. The new taxa are well supported by phenotypic (especially conidial ornamentation under SEM, production of red exudate and red pigments), physiological (growth at 37 °C, response to cycloheximide and CREA), chemotaxonomic (production of specific extrolites), and multilocus phylogenetic analysis using RNA-polymerase II second largest subunit (RPB2), partial tubulin (benA), and calmodulin (CaM). Both new taxa are resolved within the section Exilicaulis in series Restricta and show phylogenetic affiliation to P. restrictum sensu stricto. They produce a large spectrum of toxic anthraquinoid pigments, namely, monomeric anthraquinones related to emodic and chloremodic acids and other interesting bioactive extrolites (i.e., endocrocin, paxilline, pestalotin, and 7-hydroxypestalotin). Of note, two bianthraquinones (i.e., skyrin and oxyskyrin) were detected in a culture extract of P. silybi. Two new chloroemodic acid derivatives (2-chloro-isorhodoptilometrin and 2-chloro-desmethyldermoquinone) isolated from the exudate of P. krskae ex-type culture were analyzed by nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS).

Phytochemical and pharmacological investigation of Spiraea chamaedryfolia: a contribution to the chemotaxonomy of Spiraea genus.

OBJECTIVE: Diterpene alkaloids are secondary plant metabolites and chemotaxonomical markers with a strong biological activity. These compounds are characteristic for the Ranunculaceae family, while their occurrence in other taxa is rare. Several species of the Spiraea genus (Rosaceae) are examples of this rarity. Screening Spiraea species for alkaloid content is a chemotaxonomical approach to clarify the classification and phylogeny of the genus. Novel pharmacological findings make further investigations of Spiraea diterpene alkaloids promising. RESULTS: Seven Spiraea species were screened for diterpene alkaloids. Phytochemical and pharmacological investigations were performed on Spiraea chamaedryfolia, the species found to contain diterpene alkaloids. Its alkaloid-rich fractions were found to exert a remarkable xanthine-oxidase inhibitory activity and a moderate antibacterial activity. The alkaloid distribution within the root was clarified by microscopic techniques.