Therapeutic effect of iturin A on Candida albicans oral infection and its pathogenic factors.

Candida albicans is responsible for conditions ranging from superficial infections such as oral or vaginal candidiasis to potentially fatal systemic infections. It produces pathogenic factors contributing to its virulence. Iturin A, a lipopeptide derived from Bacillus sp., exhibits a significant inhibitory effect against C. albicans. However, its exact mechanism in mitigating the pathogenic factors of C. albicans remains to be elucidated. This study aimed to explore the influence of iturin A on several pathogenic attributes of C. albicans, including hypha formation, cell membrane permeability, cell adhesion, biofilm formation, and therapeutic efficacy in an oral C. albicans infection model in mice. The minimal inhibitory concentration of iturin A against C. albicans was determined to be 25 µg/mL in both YEPD and RPMI-1640 media. Iturin A effectively inhibited C. albicans hyphal formation, decreased cell viability within biofilms, enhanced cell membrane permeability, and disrupted cell adhesion in vitro. Nonetheless, iturin A did not significantly affect the phospholipase activity or hydrophobicity of C. albicans. A comparative study with nystatin demonstrated the superior therapeutic efficacy of iturin A in a mouse model of oral C. albicans infection, significantly decreasing C. albicans count and inhibiting both fungal hypha formation and tongue surface adhesion. High-dose iturin A treatment (25 µg/mL) in mice had no significant effects on blood indices, tongue condition, or body weight, indicating the potential for iturin A in managing oral infections. This study confirmed the therapeutic potential of iturin A and provided valuable insights for developing effective antifungal therapies targeting C. albicans pathogenic factors.

Multifunctional Gold Nanozyme-Engineered Amphotericin B for Enhanced Antifungal Infection Therapy.

Chronic wounds of significant severity and acute injuries are highly vulnerable to fungal infections, drastically impeding the expected wound healing trajectory. The clinical use of antifungal therapeutic drug is hampered by poor solubility, high toxicity and adverse reactions, thereby necessitating the urgent development of novel antifungal therapy strategy. Herein, this study proposes a new strategy to enhance the bioactivity of small-molecule antifungal drugs based on multifunctional metal nanozyme engineering, using amphotericin B (AmB) as an example. AmB-decorated gold nanoparticles (AmB@AuNPs) are synthesized by a facile one-pot reaction strategy, and the AmB@AuNPs exhibit superior peroxidase (POD)-like enzyme activity, with maximal reaction rates (Vmax ) 3.4 times higher than that of AuNPs for the catalytic reaction of H2 O2 . Importantly, the enzyme-like activity of AuNPs significantly enhanced the antifungal properties of AmB, and the minimum inhibitory concentrations of AmB@AuNPs against Candida albicans (C. albicans) and Saccharomyces cerevisiae (S. cerevisiae) W303 are reduced by 1.6-fold and 50-fold, respectively, as compared with AmB alone. Concurrent in vivo studies conducted on fungal-infected wounds in mice underscored the fundamentally superior antifungal ability and biosafety of AmB@AuNPs. The proposed strategy of engineering antifungal drugs with nanozymes has great potential for enhanced therapy of fungal infections and related diseases.

Early clinical efficacy of pegylated interferon treatment in patients with different phases of chronic HBV infection: A real-world analysis.

Although there are therapeutic advantages for hepatitis B virus (HBV) withpegylated interferon alpha (peg-IFNα) treatment compared with nucleos(t)ide analog (NAs) therapy, the effect difference in infected population at different phases has not been well established. We studied the clinical efficacy of peg-IFNα in two populations with HBV infection, including inactive HBsAg carrier (IHC) and chronic hepatitis B (CHB). A total of 328 HBV-infected patients were included in this real-world analysis. Patients were divided into two groups according to the infected stages. Peg-IFNα monotherapy or combination therapy with NAs were used in IHCs, and peg-IFNα added-on NAs therapy was applied to patients with CHB. The primary efficacy endpoint was HBsAg loss at Week 24. Results: The Kaplan-Meier cumulative rates of HBsAg loss were 39.50% (n = 47/119) in IHC group and 28.71% (n = 60/209) in CHB group at Week 24 (p < .05). After Propensity Score Matching (PSM), the HBsAg loss rates were 36.84% (n = 35/95) and 32.63% (n = 31/95), respectively (p > .05). Patients with baseline HBsAg level < 100 IU/ml achieved higher rates of HBsAg clearance in IHC and CHB group (before PSM: 47.44% vs. 42.86%, after PSM: 49.12% vs. 45.83%, all p values > .05). Baseline HBsAg level and its level decline from baseline to Week 12 can be as the predictors for HBsAg loss at Week 24 in both groups. Hence, the efficacy of HBsAg clearance was broadly similar between IHCs and NA-treated CHB patients during the early peg-IFNα therapy. A significant downward trend of HBsAg level was observed in both groups during peg-IFNα therapy.

Potential role of selenium in alleviating obesity-related iron dyshomeostasis.

Obesity is a serious health problem in modern life and increases the risk of many comorbidities including iron dyshomeostasis. In contrast to malnourished anemia, obesity-related iron dyshomeostasis is mainly caused by excessive fat accumulation, inflammation, and disordered gut microbiota. In obesity, iron dyshomeostasis also induces disorders associated with gut microbiota, neurodegenerative injury, oxidative damage, and fat accumulation in the liver. Selenium deficiency is often accompanied by obesity or iron deficiency, and selenium supplementation has been shown to alleviate obesity and overcome iron deficiency. Selenium inhibits fat accumulation and exhibits anti-inflammatory activity. It regulates gut microbiota, prevents neurodegenerative injury, alleviates oxidative damage to the body, and ameliorates hepatic fat accumulation. These effects theoretically meet the requirements for the inhibition of factors underlying obesity-related iron dyshomeostasis. Selenium supplementation may have a potential role in the alleviation of obesity-related iron dyshomeostasis. This review verifies this hypothesis in theory. All the currently reported causes and results of obesity-related iron dyshomeostasis are reviewed comprehensively, together with the effects of selenium. The challenges and strategies of selenium supplementation are also discussed. The findings demonstrate the possibility of selenium-containing drugs or functional foods in alleviating obesity-related iron dyshomeostasis.

High homocysteine is associated with idiopathic normal pressure hydrocephalus in deep perforating arteriopathy: a cross-sectional study.

BACKGROUND AND OBJECTIVE: The pathogenesis and pathophysiology of idiopathic normal pressure hydrocephalus (iNPH) remain unclear. Homocysteine may reduce the compliance of intracranial arteries and damage the endothelial function of the blood-brain barrier (BBB), which may be the underlying mechanism of iNPH. The overlap cases between deep perforating arteriopathy (DPA) and iNPH were not rare for the shared risk factors. We aimed to investigate the relationship between serum homocysteine and iNPH in DPA. METHODS: A total of 41 DPA patients with iNPH and 49 DPA patients without iNPH were included. Demographic characteristics, vascular risk factors, laboratory results, and neuroimaging data were collected. Multivariable logistic regression analysis was performed to investigate the relationship between serum homocysteine and iNPH in DPA patients. RESULTS: Patients with iNPH had significantly higher homocysteine levels than those without iNPH (median, 16.34 mmol/L versus 14.28 mmol/L; P = 0.002). There was no significant difference in CSVD burden scores between patients with iNPH and patients without iNPH. Univariate logistic regression analysis demonstrated that patients with homocysteine levels in the Tertile3 were more likely to have iNPH than those in the Tertile1 (OR, 4.929; 95% CI, 1.612-15.071; P = 0.005). The association remained significant after multivariable adjustment for potential confounders, including age, male, hypertension, diabetes mellitus, atherosclerotic cardiovascular disease (ASCVD) or hypercholesterolemia, and eGFR level. CONCLUSION: Our study indicated that high serum homocysteine levels were independently associated with iNPH in DPA. However, further research is needed to determine the predictive value of homocysteine and to confirm the underlying mechanism between homocysteine and iNPH.

COST1 regulates autophagy to control plant drought tolerance.

Plants balance their competing requirements for growth and stress tolerance via a sophisticated regulatory circuitry that controls responses to the external environments. We have identified a plant-specific gene, COST1 (constitutively stressed 1), that is required for normal plant growth but negatively regulates drought resistance by influencing the autophagy pathway. An Arabidopsis thaliana cost1 mutant has decreased growth and increased drought tolerance, together with constitutive autophagy and increased expression of drought-response genes, while overexpression of COST1 confers drought hypersensitivity and reduced autophagy. The COST1 protein is degraded upon plant dehydration, and this degradation is reduced upon treatment with inhibitors of the 26S proteasome or autophagy pathways. The drought resistance of a cost1 mutant is dependent on an active autophagy pathway, but independent of other known drought signaling pathways, indicating that COST1 acts through regulation of autophagy. In addition, COST1 colocalizes to autophagosomes with the autophagosome marker ATG8e and the autophagy adaptor NBR1, and affects the level of ATG8e protein through physical interaction with ATG8e, indicating a pivotal role in direct regulation of autophagy. We propose a model in which COST1 represses autophagy under optimal conditions, thus allowing plant growth. Under drought, COST1 is degraded, enabling activation of autophagy and suppression of growth to enhance drought tolerance. Our research places COST1 as an important regulator controlling the balance between growth and stress responses via the direct regulation of autophagy.

Simulated Microgravity Accelerates Alloy Corrosion by Aspergillus sp. via the Enhanced Production of Organic Acids.

Metal corrosion caused by Aspergillus sp. was shown to be significantly enhanced on a space station, but its mechanism is still unknown. To simulate this on earth, the corrosion capability of A. carbonarius on five metal sheets was investigated under simulated microgravity. Also, the effect of metal ions on growth and organic acid production was determined. Results showed that A. carbonarius could corrode all five types of metal, including Ti alloy, aluminum alloy, iron, and aluminum and copper sheet, and the corrosion was intensified under simulated microgravity. Energy dispersive X-ray spectrometry (EDS) analysis showed that metal ions enriched on A. carbonarius spores, especially iron, aluminum ions, and copper ions, indicating that A. carbonarius can use these metal ions. In particular, the content of oxalic acid was significantly increased after A. carbonarius cocultured with five metal materials under simulated microgravity. Al3+, Fe3+, and Cu2+ at the concentration of 0.3 mg/mL and Mg2+ at 0.8 mg/mL significantly promoted the growth and oxalic acid and citric acid production of A. carbonarius and A. niger under normal gravity and simulated microgravity. Comparing the impact of metal ions and metal sheets on the production of organic acids, it can be inferred that oxalic acid may dominate in the corrosion process of A. carbonarius. In summary, molds promoted metal corrosion by producing organic acids, and the released metal ions will further promote the growth of mold and the accumulation of organic acids. This may be an important reason for the intensification of mold corrosion under microgravity. IMPORTANCE The space station and other long-term manned spacecrafts will experience the risk of microbial corrosion, especially mold, which will be harmful to the platform system and astronauts. Aspergillus sp. has been widely reported to produce organic acids that corrode and destroy materials, and the ability of these crafts to fly through space can be significantly affected. Research on the mechanism that causes enhanced corrosion ability of fungi in space stations is important to control their growth. Our research focuses on the interaction between mold and metals. In particular, it is found that metal ions promote mold growth and produce organic acids, thus accelerating mold corrosion of metals. Our results provide a new perspective for the control of fungal corrosion under simulated microgravity.

A simple technology for plastid transformation with fragmented DNA.

Plastid engineering has several unique advantages such as high expression of transgenes due to high polyploidy of plastid genomes and environmental biosafety because of maternal inheritance of transgenes, and has become a promising tool for molecular farming, metabolic engineering, and genetic improvement. However, there are no standard vectors available for plastid transformation. Moreover, the construction of plastid transformation vectors containing long operons or genes encoding proteins that are toxic to Escherichia coli was tedious or difficult. Here, we developed a simple plastid transformation technology without the need for in vitro vector construction by using multiple linear DNA fragments which share homologous sequences (HSs) at their ends. The strategy is based on homologous recombination between HSs of DNA fragments via endogenous recombination machinery in plastids, which subsequently are integrated into the plastid genome. We found that HSs of 200 bp or longer were sufficient for mediating the integration into the plastid genome with at least similar efficiency to that of plasmid DNA-based plastid transformation. Furthermore, we successfully used this method to introduce a phage lysin-encoding gene and a long operon into a tobacco plastid genome. The establishment of this technology simplifies the plastid transformation procedure and provides a novel solution for expressing proteins, which are either toxic to the cloning host or large operons in plastids, without need of vector cloning.

The capability of Bacillus pseudomycoides from soil to remove Cu(II) in water and prevent it from entering plants.

AIMS: Copper ion is widespread in wastewater and threatens the condition and human health. Micro-organisms have unique advantages to remove heavy-metal ions from water, but are rarely reported in the removal of copper ion. This aims to develop micro-organisms that can remove copper ion in water, characterize their properties and analyse their potential application in practice. METHODS AND RESULTS: Sewage sludge was used as the source to isolate wild bacteria that can remove copper ion in water. The most efficient strain was screened out from 23 obtained isolates, identified as Bacillus pseudomycoides and coded as C6. The properties of C6 in the removal of copper ion in water were investigated in the aspects of reaction conditions, reaction groups, reaction dynamic and the application in oat planting. The reaction at pH 7 within 10 min yielded the highest removal rate of copper ion, 83%. The presence of lead ion in the reaction system could promote the removal rate of copper ion. Carboxyl groups and amidogen of C6 biomass were mainly involved in the removal of copper ion. The removal of copper ion was in accord with single-layer adsorption and Langmuir adsorption isotherm model. In application, C6 biomass reduced the copper content in the oat seedlings grown in copper ion containing water by more than seven times. CONCLUSIONS: B. pseudomycoides C6 can efficiently remove copper ion in water and inhibit it from entering plants. SIGNIFICANCE AND IMPACT OF STUDY: This is the first time to report the capability of B. pseudomycoides to remove copper ion in water, which is also more efficient than the currently reported chemical and biological methods.

The clinical effect of WeChat-based MUST education model on patients with chronic heart failure.

OBJECTIVE: To explore the effect of WeChat-based MUST nursing intervention on self-care ability and quality of life in patients with chronic heart failure. METHOD: Convenient sampling was used to select CHF patients who received treatment in XX Hospital from January 1, 2020, to December 30, 2020, as the study subjects and was divided into the experimental group (n = 60) and the control group (n = 60) according to the random number table. The experimental group used the WeChat-based MUST nursing intervention, and the control group used the routine education and follow-up model. Cardiac function parameters, self-care ability, and other indicators were compared between the two groups before and after nursing. The clinical effect of two groups was evaluated. RESULTS: After the nursing intervention, LVEF levels were increased to different extents and NT-proBNP was decreased to different extents in both groups. LVEF level in the experimental group was higher than that in the control group, and the NT-proBNP level in the experimental group was lower than that in the control group. After the nursing intervention, the self-care ability and quality of life of the two groups were increased to varying degrees. Self-care ability was higher in the experimental group than in the control group, and quality of life was higher in the experimental group than in the control group. CONCLUSION: The WeChat-based MUST nursing intervention model in patients with chronic heart failure, compared with the conventional cardiology nursing model, can effectively improve the self-care ability of patients, improve the knowledge level and quality of life of patients with heart failure, and reduce the readmission rate.

Development of a microecologic product from Lactobacillus rhamnosus based on silica.

BACKGROUND: Probiotics are primarily made into microecologic products for use in the food and feed industries. The freeze-drying technique is widely used in their preparation to maintain their high level of bioactivity. This causes high costs in terms of the energy and time needed. In this study, we developed a method to produce a highly active microecologic product from Lactobacillus rhamnosus using heating and silica. RESULTS: A microecologic product was made successfully from L. rhamnosus using the whole bacterial culture broth, without waste, and using food-grade silica (4.5 mL g-1 ) to absorb water before drying at 37 °C for 8 h. The activity of L. rhamnosus cells was increased significantly by adding water extracts of green tea to the culture medium. The viable amount of L. rhamnosus in the obtained microecologic product was 9.80 × 1010 cfu g-1 with a survival rate of 224.67% in simulated gastric juice for 3 h and 68.2% in simulated intestinal juice for 3 h. The microecologic product treated an intestinal infection by multi-drug-resistant Staphylococcus aureus in mice very efficiently. CONCLUSION: The study developed an economic, eco-friendly, and efficient method for preparing highly active microecologic agents using heating and without waste. © 2022 Society of Chemical Industry.

PtBRI1.2 promotes shoot growth and wood formation through a brassinosteroid-mediated PtBZR1-PtWNDs module in poplar.

Brassinosteroid-insensitive-1 (BRI1) plays important roles in various signalling pathways controlling plant growth and development. However, the regulatory mechanism of BRI1 in brassinosteroid (BR)-mediated signalling for shoot growth and wood formation in woody plants is largely unknown. In this study, PtBRI1.2, a brassinosteroid-insensitive-1 gene, was overexpressed in poplar. Shoot growth and wood formation of transgenic plants were examined and the regulatory genes involved were verified. PtBRI1.2 was localized to the plasma membrane, with a predominant expression in leaves. Ectopic expression of PtBRI1.2 in Arabidopsis bri1-201 and bri1-5 mutants rescued their retarded-growth phenotype. Overexpression of PtBRI1.2 in poplar promoted shoot growth and wood formation in transgenic plants. Further studies revealed that overexpression of PtBRI1.2 promoted the accumulation of PtBZR1 (BRASSINAZOLE RESISTANT1) in the nucleus, which subsequently activated PtWNDs (WOOD-ASSOCIATED NAC DOMAIN transcription factors) to up-regulate expression of secondary cell wall biosynthesis genes involved in wood formation. Our results suggest that PtBRI1.2 plays a crucial role in regulating shoot growth and wood formation by activating BR signalling.

Antifungal activity of silver nanoparticles synthesized by iturin against Candida albicans in vitro and in vivo.

Candida albicans (C. albicans) is a fungal pathogen that is difficult to cure clinically due to lack of effective antifungal agents with low toxicity. In this study, iturin, a cyclic peptide having wide antifungal spectrum, was used to synthesize nanosilver particles (AgNPs), and a complex of iturin-AgNPs was formed. The antifungal activity of iturin-AgNPs against C. albicans and its mechanisms were tested in vitro. Iturin-AgNPs were also loaded in chitosan (CS) composite dressing and applied to skin wound healing in mice. As results, iturin-AgNPs showed excellent antifungal activity with the minimum inhibitory concentrations (MIC) of 1.25, 2.5, and 5 µg/mL at C. albicans concentrations of 1×105, 1×106, and 1×107 CFU/mL, respectively. The MIC value still kept at 2.5 µg/mL against C. albicans (105 CFU/mL) after 15 regeneration, showing less induction of drug resistance to the pathogenic fungus. The antifungal mechanisms of iturin-AgNPs against C. albicans were identified as the increase of membrane permeability, damage of cell membrane integrity, and leakage of cellular protein and nucleic acids. No toxicity was found for iturin-AgNPs to HaCaT cells at concentrations of lower than 10 µg/mL. In wound healing application, iturin-AgNP CS composite dressing significantly accelerated the healing of C. albicans infected skin wounds at the early 10 days. In conclusion, iturin-AgNPs were developed as an efficient antifungal agent against C. albicans in vitro and in vivo and showed potential application in wound healing promotion.

Protection of Fecal Microbiota Transplantation in a Mouse Model of Multiple Sclerosis.

Given the growing evidence of a link between gut microbiota (GM) dysbiosis and multiple sclerosis (MS), fecal microbiota transplantation (FMT), aimed at rebuilding GM, has been proposed as a new therapeutic approach to MS treatment. To evaluate the viability of FMT for MS treatment and its impact on MS pathology, we tested FMT in mice with experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. We provide evidence that FMT can rectify altered GM to some extent with a therapeutic effect on EAE. We also found that FMT led to reduced activation of microglia and astrocytes and conferred protection on the blood-brain barrier (BBB), myelin, and axons in EAE. Taken together, our data suggest that FMT, as a GM-based therapy, has the potential to be an effective treatment for MS.

Iturin A-like lipopeptides from Bacillus subtilis trigger apoptosis, paraptosis, and autophagy in Caco-2 cells.

This study revealed that iturin A-like lipopeptides produced by Bacillus subtillis induced both paraptosis and apoptosis in heterogeneous human epithelial colorectal adenocarcinoma (Caco-2) cells. Autophagy was simultaneously induced in Caco-2 cells treated with iturin A-like lipopeptides at the early stage and inhibited at the later stage. A western blot analysis showed that the lipopeptides induced apoptosis in Caco-2 cells via a mitochondrial-dependent pathway, as indicated by upregulated expression of the apoptotic genes bax and bad and downregulated expression of the antiapoptotic gene bcl-2. The induction of paraptosis in Caco-2 cells was indicated by the occurrence of many cytoplasmic vacuoles accompanied by endoplasmic reticulum (ER) dilatation and mitochondrial swelling and dysfunction. ER stress also occurred with significant increases in reactive oxygen species and Ca2+ levels in cells. Autophagy was detected by a transmission electron microscopy analysis and by upregulated expression of LC3-II and downregulated expression of LC3-I. The inhibition of autophagy at the later stage was shown by upregulated expression of p62. This study revealed the capability of iturin A-like B. subtilis lipopeptides to simultaneously execute antitumor potential via multiple pathways.

Correction to: Accumulation of glycine betaine in transplastomic potato plants expressing choline oxidase confers improved drought tolerance.

Unfortunately, one of the author names has been misspelled in the original publication. The correct spelling is Qiping Song.

Accumulation of glycine betaine in transplastomic potato plants expressing choline oxidase confers improved drought tolerance.

MAIN CONCLUSION: Plastid genome engineering is an effective method to generate drought-resistant potato plants accumulating glycine betaine in plastids. Glycine betaine (GB) plays an important role under abiotic stress, and its accumulation in chloroplasts is more effective on stress tolerance than that in cytosol of transgenic plants. Here, we report that the codA gene from Arthrobacter globiformis, which encoded choline oxidase to catalyze the conversion of choline to GB, was successfully introduced into potato (Solanum tuberosum) plastid genome by plastid genetic engineering. Two independent plastid-transformed lines were isolated and confirmed as homoplasmic via Southern-blot analysis, in which the mRNA level of codA was much higher in leaves than in tubers. GB accumulated in similar levels in both leaves and tubers of codA-transplastomic potato plants (referred to as PC plants). The GB content was moderately increased in PC plants, and compartmentation of GB in plastids conferred considerably higher tolerance to drought stress compared to wild-type (WT) plants. Higher levels of relative water content and chlorophyll content under drought stress were detected in the leaves of PC plants compared to WT plants. Moreover, PC plants presented a significantly higher photosynthetic performance as well as antioxidant enzyme activities during drought stress. These results suggested that biosynthesis of GB by chloroplast engineering was an effective method to increase drought tolerance.

Clinostat Rotation Affects Metabolite Transportation and Increases Organic Acid Production by Aspergillus carbonarius, as Revealed by Differential Metabolomic Analysis.

Contamination by fungi may pose a threat to the long-term operation of the International Space Station because fungi produce organic acids that corrode equipment and mycotoxins that harm human health. Microgravity is an unavoidable and special condition in the space station. However, the influence of microgravity on fungal metabolism has not been well studied. Clinostat rotation is widely used to simulate the microgravity condition in studies carried out on Earth. Here, we used metabolomics differential analysis to study the influence of clinostat rotation on the accumulation of organic acids and related biosynthetic pathways in ochratoxin A (OTA)-producing Aspergillus carbonarius As a result, clinostat rotation did not affect fungal cell growth or colony appearance but significantly increased the accumulation of organic acids, particularly isocitric acid, citric acid, and oxalic acid, and OTA both inside cells and in the medium, as well as resulted in a much higher level of accumulation of some products inside than outside cells, indicating that the transport of these metabolites from the cell to the medium was inhibited. This finding corresponded to the change in the fatty acid composition of cell membranes and the reduced thickness of the cell walls and cell membranes. Amino acid and energy metabolic pathways, particularly the tricarboxylic acid cycle, were influenced the most during clinostat rotation compared to the effects of normal gravity on these pathways.IMPORTANCE Fungi are ubiquitous in nature and have the ability to corrode various materials by producing metabolites. Research on how the space station environment, especially microgravity, affects fungal metabolism is helpful to understand the role of fungi in the space station. This work provides insights into the mechanisms involved in the metabolism of the corrosive fungus Aspergillus carbonarius under simulated microgravity conditions. Our findings have significance not only for preventing material corrosion but also for ensuring food safety, especially in the space environment.

Genomic sequencing, genome-scale metabolic network reconstruction, and in silico flux analysis of the grape endophytic fungus Alternaria sp. MG1.

BACKGROUND: Alternaria sp. MG1, an endophytic fungus isolated from grape, is a native producer of resveratrol, which has important application potential. However, the metabolic characteristics and physiological behavior of MG1 still remains mostly unraveled. In addition, the resveratrol production of the strain is low. Thus, the whole-genome sequencing is highly required for elucidating the resveratrol biosynthesis pathway. Furthermore, the metabolic network model of MG1 was constructed to provide a computational guided approach for improving the yield of resveratrol. RESULTS: Firstly, a draft genomic sequence of MG1 was generated with a size of 34.7 Mbp and a GC content of 50.96%. Genome annotation indicated that MG1 possessed complete biosynthesis pathways for stilbenoids, flavonoids, and lignins. Eight secondary metabolites involved in these pathways were detected by GC-MS analysis, confirming the metabolic diversity of MG1. Furthermore, the first genome-scale metabolic network of Alternaria sp. MG1 (named iYL1539) was reconstructed, accounting for 1539 genes, 2231 metabolites, and 2255 reactions. The model was validated qualitatively and quantitatively by comparing the in silico simulation with experimental data, and the results showed a high consistency. In iYL1539, 56 genes were identified as growth essential in rich medium. According to constraint-based analysis, the importance of cofactors for the resveratrol biosynthesis was successfully demonstrated. Ethanol addition was predicted in silico to be an effective method to improve resveratrol production by strengthening acetyl-CoA synthesis and pentose phosphate pathway, and was verified experimentally with a 26.31% increase of resveratrol. Finally, 6 genes were identified as potential targets for resveratrol over-production by the recently developed methodology. The target-genes were validated using salicylic acid as elicitor, leading to an increase of resveratrol yield by 33.32% and the expression of gene 4CL and CHS by 1.8- and 1.6-fold, respectively. CONCLUSIONS: This study details the diverse capability and key genes of Alternaria sp. MG1 to produce multiple secondary metabolites. The first model of the species Alternaria was constructed, providing an overall understanding of the physiological behavior and metabolic characteristics of MG1. The model is a highly useful tool for enhancing productivity by rational design of the metabolic pathway for resveratrol and other secondary metabolites.

Beneficial effects of endophytic fungi colonization on plants.

Due to increasingly limited water resources, diminishing farmland acreage, and potentially negative effects of climate change, an urgent need exists to improve agricultural productivity to feed the ever-growing population. Plants interact with microorganisms at all trophic levels, adapting growth, developmental, and defense responses within a complicated network of community members. Endophytic fungi have been widely reported for their ability to aid in the defense of their host plants. Currently, many reports focus on the application of endophytic fungi with the capability to produce valuable bioactive molecules, while others focus on endophytic fungi as biocontrol agents. Plant responses upon endophytic fungi colonization are also good for the immune system of the plant. In this paper, the possible mechanisms between endophytic fungi and their hosts were reviewed. During long-term evolution, plants have acquired numerous beneficial strategies in response to endophytic fungi colonization. The interaction of endophytic fungi with plants modulates the relationship between plants and both biotic and abiotic stresses. It has previously been reported that this endophytic relationship confers additional defensive mechanisms on the modulation of the plant immune system, as the result of the manipulation of direct antimicrobial metabolites such as alkaloids to indirect phytohormones, jasmonic acid, or salicylic acid. Furthermore, plants have evolved to cope with combinations of stresses and experiments are required to address specific questions related to these multiple stresses. This review summarizes our current understanding of the intrinsic mechanism to better utilize these benefits for plant growth and disease resistance. It contributes new ideas to increase plant fitness and crop productivity.