AaLaeA targets AaFla1 to mediate the production of antitumor compound in Alternaria alstroemeria.

Endophytic fungi are an important source of novel antitumor substances. Previously, we isolated an endophytic fungus, Alternaria alstroemeria, from the medicinal plant Artemisia artemisia, whose crude extracts strongly inhibited A549 tumor cells. We obtained a transformant, namely AaLaeAOE26 , which completely loses its antitumor activity due to overexpression of the global regulator AaLaeA. Re-sequencing analysis of the genome revealed that the insertion site was in the noncoding region and did not destroy any other genes. Metabolomics analysis revealed that the level of secondary antitumor metabolic substances was significantly lower in AaLaeAOE26 compared with the wild strain, in particular flavonoids were more downregulated according to the metabolomics analysis. A further comparative transcriptome analysis revealed that a gene encoding FAD-binding domain protein (Fla1) was significantly downregulated. On the other hand, overexpression of AaFla1 led to significant enhancement of antitumor activity against A549 with a sevenfold higher inhibition ratio than the wild strain. At the same time, we also found a significant increase in the accumulation of antitumor metabolites including quercetin, gitogenin, rhodioloside, liensinine, ginsenoside Rg2 and cinobufagin. Our data suggest that the global regulator AaLaeA negatively affects the production of antitumor compounds via controlling the transcription of AaFla1 in endophytic A. alstroemeria.

Application potential of biofertilizer-assisted Pennisetum giganteum in safe utilization of mercury-contaminated paddy fields.

High mercury (Hg) bioaccumulation in crops such as rice in Hg-contaminated areas presents a potential health hazard to humans and wildlife. To develop a safe alternative technique, bacillus-inoculated biofertilizer, citric acid, earthworms, and selenium-modified activated clay were compared for their ability to regulate Hg bioaccumulation in Pennisetum giganteum (P. giganteum). This biofertilizer significantly increased Bacillus sp. abundance in the soil by 157.12%, resulting in the removal of 27.52% of water-soluble Hg fractions through volatilization and adsorption mechanisms. The variation in bioavailable Hg in the soil significantly reduced the total Hg concentration in P. giganteum young leaves, old leaves, stems, and roots of P. giganteum by 74.14%, 48.08%, 93.72%, and 50.91%, respectively (p < 0.05), which is lower than the Chinese feed safety standard (100 ng g-1). The biofertilizer inhibitory potential was highly consistent with that of the selenium-modified activated clay. Biofertilizers significantly reduced the methylmercury concentration in various P. giganteum tissues (p < 0.05), whereas selenium-modified activated clay failed to achieve a comparable effect. This biofertilizer-assisted planting pattern can achieve an economic income quadruple that of the rice planting pattern in the Hg-contaminated paddy fields. Because of its significant environmental and financial applications, the biofertilizer-assisted planting pattern is expected to replace Hg-contaminated paddy fields.

Endophytic fungus Biscogniauxia petrensis produces antibacterial substances.

Widespread drug resistance and limited antibiotics challenge the treatment of pathogenic bacteria, which leads to a focus on searching for new antimicrobial lead compounds. We found the endophytic fungus Biscogniauxia petrensis MFLUCC14-0151 from the medicinal plant Dendrobium harveyanum had antibacterial activity for the first time. This work aimed to reveal the capacity of Biscogniauxia petrensis MFLUCC14-0151 against foodborne pathogenic bacteria and identify its bioactive substances. Bioassay-guided isolation led to the discovery of six infrequent active monomers, including (10R)-Xylariterpenoid B (1), Xylariterpenoid C (2), Tricycloalternarene 1b (3), Tricycloalternarene 3b (4), Funicin (5) and Vinetorin (6) from MFLUCC14-0151 for the first time. The results of antibacterial tests showed that (10R)-Xylariterpenoid B and Xylariterpenoid C exhibited inhibitory activities against Streptococcus agalactiae with MIC values ranging from 99.21 to 100.00 µM, and against Streptococcus aureus with MIC values ranging from 49.60 to 50.00 µM. Tricycloalternarene 1b and Tricycloalternarene 3b showed inhibitory effects on Streptococcus agalactiae with MIC values ranging from 36.13 to 75.76 µM. Unexpectedly, Funicin and Vinetorin exhibited remarkable antagonistic activities against Streptococcus agalactiae with MIC values of 10.35 and 10.21 µM, respectively, and against Streptococcus aureus with MIC values of 5.17 and 20.42 µM, respectively. In conclusion, we suggest that the isolated compounds Funicin and Vinetorin may be promising lead compounds for natural antibacterial agents.

Global regulatory factor AaLaeA upregulates the production of antitumor substances in the endophytic fungus Alternaria alstroemeria.

The global regulatory factor LaeA has been shown to be involved in the biosynthesis of secondary metabolites in various fungi. In a previous work, we isolated an endophytic fungus from Artemisia annua, and its extract had a significant inhibitory effect on the A549 cancer cell line. Phylogenetic analysis further identified the strain as Alternaria alstroemeria. Overexpression of AalaeA gene resulted in significantly increased antitumor activity of this strain's extract. The 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay results showed that the inhibition rate of the AalaeAOE29 mutant extract on A549 cancer cells was significantly higher than that of the WT extract, as the IC50 decreased from 195.0 to 107.4 µg/ml, and the total apoptosis rate was enhanced. Overexpression of the AalaeA gene significantly increased the contents of myricetin, geraniol, ergosterol, and 18 other antitumor compounds as determined by metabolomic analysis. Transcriptomic analysis revealed significant changes in 95 genes in the mutant strain, including polyketide synthases, nonribosomal peptide synthases, cytochrome P450s, glycosyltransferases, acetyl-CoA acetyltransferases, and others. These results suggested that AaLaeA mediated the antitumor activity of the metabolites in A. alstroemeria by regulating multiple metabolic pathways.

Global regulatory factor VeA upregulates the production of antitumor substances in endophytic Fusarium solani.

A number of studies have demonstrated that endophytic fungi have the potential to produce antitumor active substances with novel structures and significant activities. In our previous studies, we isolated a Fusarium strain from the stem of the medicinal plant Nothapodytes pittosporoides (Oliv.). In this study, we identified this strain as Fusarium solani and found that its crude extract has significant antitumor activity against human alveolar adenocarcinoma cells (A549). We overexpressed the global regulatory factor VeA in F. solani (VeAOE), resulting in a significant increase in antitumor activity. The MTT assay results showed that the inhibition rate of the VeAOE mutant extract on A549 cancer cells was significantly higher than that of the WT extract, as the IC50 decreased from 369.22 to 285.89 µg/mL, and the apoptosis ratio was significantly increased by approximately 4.86-fold. In VeAOE, accumulation of alkaloids, terpenoids, carboxylic acid derivatives, phenols and flavonoid metabolites with potential antitumor activity was significantly increased compared with WT based on metabolomic analysis. Additionally, transcriptome analysis found that the expression patterns of 48 genes related to antitumor activity were significantly changed in VeAOE, mainly involving glycosyl hydrolases, the Zn(2)-Cys(6) class, cytochrome P450 monooxygenase, 3-isopropylmalate dehydratase, and polyketide synthases. These results suggested that VeA mediated the antitumor activity of the metabolites in F. solani HB1-J1 by regulating multiple metabolic pathways.

Overexpression of the global regulator FnVeA upregulates antitumor substances in endophytic Fusarium nematophilum.

The special niche of endophytic fungi promotes their potential to produce antitumor compounds with novel structure and significant bioactivity for screening of new antitumor drugs. In our previous studies, we isolated a Fusarium strain from the roots of the medicinal plant Nothapodytes pittosporoides and identified it as Fusarium nematophilum. We found that the crude extract of F. nematophilum had significant antitumor activity on A549 cancer cells, and overexpressing the global regulatory factor FnVeA (the VeA gene of the fungus F. nematophilum) resulted in a significant increase in the antitumor activity, which was approximately fivefold higher than wild strain for relative inhibition rate. In FnVeAOE, the accumulation of indole, alkene, alkaloid, steroid, and flavonoid metabolites with potential antitumor activity was significantly upregulated compared with wild type via metabolomic analysis. Moreover, the transcriptome analysis showed that 134 differential genes were considered to be closely related to the biosynthesis of antitumor substances, of which 59 differential genes were considered as candidate key genes, and related to tryptophan dimethylallyltransferase, cytochrome P450 monooxygenase, polyketide synthases, and transcription factors. Taken together, we suggest that FnVeA may regulate the biosynthesis of antitumor substances by mediating the expression of genes related to secondary metabolic pathways in F. nematophilum.

A Bilobalide-Producing Endophytic Fungus, Pestalotiopsis uvicola from Medicinal Plant Ginkgo biloba.

For screening bilobalide (BB)-producing endophytic fungi from medicinal plant Ginkgo biloba, a total of 57 fungal isolates were isolated from the internal stem, root, leaf, and bark of the plant G. biloba. Fermentation processes using BB-producing fungi other than G. biloba may become a novel way to produce BB, which is a terpene trilactones exhibiting neuroprotective effects. In this study, a BB-producing endophytic fungal strain GZUYX13 was isolated from the leaves of G. biloba grown in the campus of Guizhou University, Guiyang city, Guizhou province, China. The strain produced BB when grown in potato dextrose liquid medium. The amount of BB produced by this endophytic fungus was quantified to be 106 µg/L via high-performance liquid chromatography (HPLC), substantially lower than that produced by the host tissue. The fungal BB which was analyzed by thin layer chromatography (TLC) and HPLC was proven to be identical to authentic BB. The strain GZUYX13 was identified as Pestalotiopsis uvicola via morphology and ITS rDNA phylogeny. To the best of our knowledge, this is the first report concerning the isolation and identification of endophytic BB-producing Pestalotiopsis spp. from the host plant, which further proved that endophytic fungi have the potential to produce bioactive compounds.

Cordycepin and N6-(2-hydroxyethyl)-adenosine from Cordyceps pruinosa and their interaction with human serum albumin.

Cordyceps pruinosa (CP) is often used as Traditional Chinese Medicine, but the substance basis of its medicinal properties is unclear. In this study, two compounds were isolated from CP cultures by column chromatography, and identified as cordycepin and N6-(2-hydroxyethyl)-adenosine (HEA) by Nuclear Magnetic Resonance. In order to understand the efficacy of these two substances as potential therapeutic agents, it is necessary to explore their binding with proteins. The molecular mechanisms of interaction between cordycepin, HEA and human serum albumin (HSA) were studied using UV and fluorescence spectroscopy. The bingding constants between HSA and cordycepin were 4.227, 3.573 and 3.076 × 10(3)·at 17, 27 and 37°C respectively, and that of HSA and HEA were 27.102, 19.409 and 13.002 × 10(3)·at the three tempretures respectively. Both cordycepin and HEA can quench the intrinsic fluorescence of HSA via static quenching, and they can bind with HSA to form complexes with a single binding site. The interaction forces between cordycepin and HSA were determined as electrostatic and hydrophobic, and those of HEA and HSA were hydrogen bonding and van der Waals forces. Using Foster's equation, the distance between fluorophores of cordycepin and HSA, and HEA and HSA are estimated to be 5.31 nm and 4.98 nm, respectively. In this study, cordycepin was isolated for the first time from CP, and will provide a new source of cordycepin and expand the use of this taxon. The interaction mechanisms between cordycepin and HSA was studied for the first time, which will provide a useful guide for the clinical application of cordycepin. The pharmacological importance of this study is to understand the interaction of HSA with cordycepin and HEA, which will be essential for the future designing of drugs based on the two compounds.

[Screening and taxonomic identification of endophytic fungi with antitumor and antioxidant activities from Artemisia lactiflora].

Artemisia lactiflora is an important medicinal plant in China. The antitumor and antioxidant activities of the extracts of 54 endophytic fungi from the plant were screened via MTT assay and DPPH scavenging radical assay, respectively. The bioactive strains were identified based on similarity of 5.8S gene and internal transcribed spacer (ITS) sequences. The results showed that extracts from ten (18.5%) isolates exhibited antitumor activity, and which from two (3.7%) isolates exhibited antioxidant activity. The Alternaria sp. GYBH47 strain was simultaneously having antagonistic activity against HL-60 leukemia, MCF-7 breast and COLO205 colon cell lines, and Phomopsis sp. GYBH42 strain having cytotoxic and antioxidant activities. The results indicated that endophytic fungi from Artemisia lactiflora are potential resources to find valuable bioactive components.