Polyene Macrolide Antibiotic Research Articles

A new polyene macrolide antibiotic, machidamycin, produced by Streptomyces sp. K22-0017.

A new polyene macrolide, machidamycin (1), and a known compound YS-822A (2), were obtained by physicochemical screening from a culture broth of Streptomyces sp. K22-0017. The structures were elucidated using MS and 1D/2D NMR analyses. Compound 1 exhibited weak antifungal activity against Candida albicans and Mucor racemosus. Furthermore, 1 showed stronger antileishmanial activity than the existing drug paromomycin.

The interaction of plant flavones with amphotericin B: Consequences for its pore-forming ability

The growth of antibiotic resistance to antifungal drugs contributes to the search for new ways to enhance their effectiveness and reduce toxicity. The undeniable advantage of polyene macrolide antibiotic amphotericin B (AmB) which ensures low pathogen resistance is its mechanism of action related to the formation of transmembrane pores in target lipid membranes. Here, we investigated the effects of plant flavones, chrysin, wogonin, baicalein, apigenin, scutellarein, luteolin, morin and fisetin on the pore-forming activity of AmB in the sterol-enriched membranes by electrophysiological assays. Сhrysin, wogonin, baicalein, apigenin, scutellarein, and luteolin were shown to decrease the AmB pore-forming activity in the bilayers composed of palmitoyloleylphosphocholine independently of their sterol composition. Morin and fisetin led to the increase and decrease in the AmB pore-forming activity in the ergosterol- and cholesterol-containing bilayers respectively. Differential scanning microcalorimetry of the gel-to-liquid crystalline phase transition of membrane forming lipids, molecular dynamics simulations, and absorbance spectroscopy revealed the possibility of direct interactions between AmB and some flavones in the water and/or in the lipid bilayer. The influence of these interactions on the antibiotic partitioning between aqueous solution and membrane and/or its transition between different states in the bilayer was discussed.

New Polyene Macrolide Compounds from Mangrove-Derived Strain Streptomyces hiroshimensis GXIMD 06359: Isolation, Antifungal Activity, and Mechanism against Talaromyces marneffei.

Mangrove-derived actinomycetes represent a rich source of novel bioactive natural products in drug discovery. In this study, four new polyene macrolide antibiotics antifungalmycin B-E (1-4), along with seven known analogs (5-11), were isolated from the fermentation broth of the mangrove strain Streptomyces hiroshimensis GXIMD 06359. All compounds from this strain were purified using semi-preparative HPLC and Sephadex LH-20 gel filtration while following an antifungal activity-guided fractionation. Their structures were elucidated through spectroscopic techniques including UV, HR-ESI-MS, and NMR. These compounds exhibited broad-spectrum antifungal activity against Talaromyces marneffei with minimum inhibitory concentration (MIC) values being in the range of 2-128 μg/mL except compound 2. This is the first report of polyene derivatives produced by S. hiroshimensis as bioactive compounds against T. marneffei. In vitro studies showed that compound 1 exerted a significantly stronger antifungal activity against T. marneffei than other new compounds, and the antifungal mechanism of compound 1 may be related to the disrupted cell membrane, which causes mitochondrial dysfunction, resulting in leakage of intracellular biological components, and subsequently, cell death. Taken together, this study provides a basis for compound 1 preventing and controlling talaromycosis.

Development and Validation of UV-Vis Spectrophotometric Method for Estimation of Amphotericin B from Hydrogel Nanoparticle

Abstract: Amphotericin B (AmB) is a polyene macrolide antibiotic that has antifungal action against the broadest range of fungal diseases as well as in some protozoan infections. There are currently no significant issues with resistance to AmB, and it is still in use today. The development of many innovative AmB formulations as lipid formulations and polymeric nanoparticles utilising UV-VIS spectrophotometry and HPLC technique has been discussed in the literature, however specifics of peak characteristics and validation data are not provided. The goal of this study was to provide an effective approach for validating AmB and to gather reliable, accurate, and consistent data on linearity, detection limit, quantification limit, accuracy, and precision using a UV-VIS spectrophotometer. The method gives a good linearity with regression of y = 0.1471x + 0.0489 (R2 = 0.9989) at 408 nm. The repeatability (inter-day) and intermediate precision (intra-day) precision studies revealed that the method is precise and reliable where all the RSD values were ˂2%. Method accuracy showed % accuracy value for all the three concentration levels ranged from 91.144 % to 101.994 % that a small change in the concentration of the drug could be accurately determined with high accuracy. Limit of detection and limit of quantification were 0.0295 (μg/ml) and 0.0895 (μg/ml) respectively. The suggested approach is straightforward and may be considered a strategy that is routinely practicable for estimating AmB.

Total Synthesis of Pentamycin by a Conformationally Biased Double Stille Ring Closure with a Trienyl-bis-stannane

The total synthesis of the potent polyene macrolide antibiotic pentamycin was accomplished by an expedient strategy involving a highly stereoselective assembly of the polyol segment in combination with an adventurous double Stille cross-coupling with a trienyl-bis-stannane closing the macrolactone and installing the sensitive pentaene fragment. Presumably, this remarkable linchpin insertion is enhanced by the linear hydrogen bonding skeleton of the polyol substrate. Further key features include a tailored Rychnovsky alkylation of cyanohydrin acetonides and elaborate Krische couplings to set the characteristic hydroxyl and hydroxymethyl bearing centers with excellent selectivity and yield. The total synthesis unequivocally confirms the full relative and absolute stereochemistry of this polyketide, including a previously uncertain hydroxyl bearing center.

Theoretical Studies of Mutual Effects between 6-m-r Hemiketalization and 26-m-r Lactonization in Pimaricin Thioesterase.

Pimaricin is a small polyene macrolide antibiotic and has been broadly used as an antimycotic and antiprotozoal agent in both humans and foods. As a thioesterase in type-I polyketide synthase, pimTE controls the 26-m-r macrolide main chain release in pimaricin biosynthesis. In this work, we sought to determine whether the 6-m-r hemiketal formation was linked to pimTE-catalyzed 26-m-r lactonization. Compared to non-hemiketal TEs, pimTE is characterized by an aspartic acid residue (D179) accessible to the U-turn motif in the acyl-enzyme intermediate. Both the covalent docking and molecular dynamics simulations demonstrate that the reactive conformations for macrocyclic lactonization are drastically promoted by the 6-m-r hemiketal. Moreover, the small-model quantum mechanistic calculations suggest that protic residues can significantly accelerate the 6-m-r hemiketal cyclization. In addition, the post-hemiketal molecular dynamic simulations demonstrate that hydrogen-bonding networks surrounding the substrate U-turn of the hairpin-shaped conformation changes significantly when the 6-m-r hemiketal is formed. In particular, the R-hemiketal intermediate is not only catalyzed by the D179 residue, but also twists the hairpin structure to the 26-m-r lactonizing pre-reaction state. By contrast, the S-hemiketal formation is unlikely catalyzed by D179, which twists the hairpin in an opposite direction. Our results propose that pimTE could be a bi-functional enzyme, which can synergistically catalyze tandem 6-m-r and 26-m-r formations during the main-chain release of pimaricin biosynthesis.

Cu(II)-Triggered Ion Channel Properties of a 2,2'-Bipyridine-Modified Amphotericin B.

The development of stimuli-responsive synthetic channels that open and close in response to physical and chemical changes in the surrounding environment has attracted attention because of their potential bioapplications such as sensing, drug release, antibiotics, and molecular manipulation tools to control membrane transport in cells. Metal coordination is ideal as a stimulus for stimuli-responsive channels because it allows for reversible gating behavior through the addition and removal of metal ions and fine-tuning of channel structure through coordination geometry defined by the type of the metal ion and ligand. We have previously reported on transition metal-ion dependent ion permeability control of Amphotericin B (AmB) modified with a metal coordination site, 2,2'-bipyridine ligand (bpy-AmB). AmB is one of the polyene macrolide antibiotics, and it is known that the interaction between AmB and ergosterol molecules is required for AmB channel formation. In contrast, the Cu2+ coordination to the bpy moiety of bpy-AmB induces formation of Ca2+ ion-permeable channels in the ergosterol-free POPC membrane. However, the details of bpy-AmB properties such as channel stability, ion selectivity, pore size, and the effect of ergosterol on channel formation remain unclear. Here, we investigate bpy-AmB channels triggered by transition metal coordination in POPC or ergosterol-containing POPC liposomes using an HPTS assay, electrophysiological measurements, and time-resolved UV-vis spectral measurements. These analyses reveal that bpy-AmB channels triggered by Cu2+ ions are more stable and have larger pore sizes than the original AmB channels and enable efficient permeation of various cations. We believe that our channel design will lead to the construction of metal coordination-triggered synthetic ion channels.

The Antifungal Antibiotic Filipin as a Diagnostic Tool of Cholesterol Alterations in Lysosomal Storage Diseases and Neurodegenerative Disorders.

Cholesterol is the most considerable member of a family of polycyclic compounds understood as sterols, and represents an amphipathic molecule, such as phospholipids, with the polar hydroxyl group located in position 3 and the rest of the molecule is completely hydrophobic. In cells, it is usually present as free, unesterified cholesterol, or as esterified cholesterol, in which the hydroxyl group binds to a carboxylic acid and thus generates an apolar molecule. Filipin is a naturally fluorescent antibiotic that exerts a primary antifungal effect with low antibacterial activity, interfering with the sterol stabilization of the phospholipid layers and favoring membrane leakage. This polyene macrolide antibiotic does not bind to esterified sterols, but only to non-esterified cholesterol, and it is commonly used as a marker to label and quantify free cholesterol in cells and tissues. Several lines of evidence have indicated that filipin staining could be a good diagnostic tool for the cholesterol alterations present in neurodegenerative (e.g., Alzheimer's Disease and Huntington Disease) and lysosomal storage diseases (e.g., Niemann Pick type C Disease and GM1 gangliosidosis). Here, we have discussed the uses and applications of this fluorescent molecule in lipid storage diseases and neurodegenerative disorders, exploring not only the diagnostic strength of filipin staining, but also its limitations, which over the years have led to the development of new diagnostic tools to combine with filipin approach.

Effect of Post-Polyketide Synthase Modification Groups on Property and Activity of Polyene Macrolides.

The biosynthesis of polyene macrolides, which are natural products produced by soil actinomycetes, have been extensively explored, and recent studies have focused on the effects of post-polyketide synthase (PKS) modifications to polyene macrolides on toxicity, water solubility, and antifungal activity. For example, there are interactions between glycosyl, carboxyl, and hydroxyl or epoxy groups generated in the post-PKS modification steps; salt bridges will be formed between carboxylate and ammonium on the mycosamine; and water bridges will be formed between hydroxy and hydroxyl on mycosamine. These interactions will affect their water solubility and substrate-recognition specificity. This review summarizes research related to these post-PKS modification groups and discusses some genetic engineering operation problems and solutions that may be encountered when modifying these post-PKS modification groups. In addition, this review provides a basis for the structural research of polyene macrolide antibiotics and contributes to comprehensive and systematic knowledge, and it may thus encourage researchers to develop novel antifungal drugs with higher therapeutic indexes and medical values.

Polyene macrolide antibiotic nanoemulsion: a proposal for the treatment of cutaneous leishmaniasis

Leishmaniasis is a neglected tropical disease that requires timely and inexpensive treatment. For this purpose, a nanoemulsion with a polyene macrolide antibiotic, or amphotericin B (NE-AmB), was developed. This study quantified the amount of drug permeated and retained in intact and lacerated human skin, simulating cutaneous leishmaniasis (CL) processes. Toxicity in macrophage and keratinocyte cell lines, activity against promastigotes and amastigotes of Leishmania tropica, in vivo irritant activity, and histological evidence was evaluated. Results. The amount of drug retained in intact and damaged skin was 750.18 ± 5.43 and 567.97 ± 8.64 µg/g/cm2, respectively. There was no permeation. No apparent toxic effect was observed in HaCaT cell lines. The IC50 of NE-AmB found for promastigotes and amastigotes was 0.26 ± 0.09 and 0.37 ± 0.05 µg/mL, respectively. NE without AmB did show antiparasitic activity. The formulation showed lower IC50 values on both parasite stages than the AmB solution. There was no skin irritation, and histology showed skin improvement with treatment. We suggest that this NE-AmB may be a candidate for in vivo studies in CL patients. Keywords. Leishmaniasis, Amphotericin B, ex vivo permeation studies, in vitro cytotoxicity, in vitro leishmanicidal activity, Draize test, histology.

Use of Polyene Macrolide Antibiotics In Combination With Dimethil Sulfoxide As Antiviral And Antifungal Agent At Plant Treatment

Use of Polyene Macrolide Antibiotics In Combination With Dimethil Sulfoxide As Antiviral And Antifungal Agent At Plant Treatment

Review of Novel Oral Amphotericin B Formulations for the Treatment of Parasitic Infections.

Amphotericin B (AmpB) is a polyene macrolide antibiotic used in the treatment of blood-borne parasitic and fungal infections. However, its use, particularly in the developing world, has been limited by dose-dependent kidney toxicity, other systemic-related toxicity issues following injection, the inconvenience of parenteral administration, and accessibility. Oral formulation approaches have focused on the dual problem of solubility and permeability of AmpB, which is poorly water soluble, amphoteric and has extremely low oral bioavailability. Therefore, to enhance oral absorption, researchers have employed micellar formulations, polymeric nanoparticles, cochleates, pro-drugs, and self-emulsifying drug delivery systems (SEDDS). This paper will highlight current uses of AmpB against parasitic infections such as leishmaniasis, preclinical and clinical formulation strategies, applications in veterinary medicine and the importance of developing a cost-effective and safe oral AmpB formulation.

Response Surface Methodology (RSM) Mediated Optimization of Medium Components for Mycelial Growth and Metabolites Production of Streptomyces alfalfae XN-04.

Streptomyces alfalfae XN-04 has been reported for the production of antifungal metabolites effectively to control Fusarium wilt of cotton, caused by Fusarium oxysporum f. sp. vasinfectum (Fov). In this study, we used integrated statistical experimental design methods to investigate the optimized liquid fermentation medium components of XN-04, which can significantly increase the antifungal activity and biomass of XN-04. Seven variables, including soluble starch, KNO3, soybean cake powder, K2HPO4, MgSO4·7H2O, CaCO3 and FeSO4·7H2O, were identified as the best ingredients based on one-factor-at-a-time (OFAT) method. The results of Plackett–Burman Design (PBD) showed that soluble starch, soybean cake powder and K2HPO4 were the most significant variables among the seven variables. The steepest climbing experiment and response surface methodology (RSM) were performed to determine the interactions among these three variables and fine-tune the concentrations. The optimal compositions of medium were as follows: soluble starch (26.26 g/L), KNO3 (1.00 g/L), soybean cake powder (23.54 g/L), K2HPO4 (0.27 g/L), MgSO4·7H2O (0.50 g/L), CaCO3 (1.00 g/L) and FeSO4·7H2O (0.10 g/L). A verification experiment was then carried out under the optimized conditions, and the results revealed the mycelial dry weight of S. alfalfae XN-04 reaching 6.61 g/L. Compared with the initial medium, a 7.47-fold increase in the biomass was achieved using the optimized medium. Moreover, the active ingredient was purified from the methanol extract of S. alfalfae XN-04 mycelium and then identified as roflamycoin (a polyene macrolide antibiotic). The results may provide new insights into the development of S. alfalfae XN-04 fermentation process and the control of the Fusarium wilt of cotton and other plant diseases.

ABC transporter SgnA/B promotes extracellular transport and efficient production of natamycin

Natamycin is a natural, broad spectrum and highly efficient antifungal compound that belongs to polyene macrolide antibiotics. It has been used in prevention of food fungal contamination and treatment of clinical fungal infection. The extracellular transport efficiency of natamycin may be an important factor hampering the yield of natamycin produced by Streptomyces gilvosporeus. The extracellular transporter SgnA/B of natamycin was analyzed by bioinformatics tools and molecular docking techniques. This ATP-binding cassette transporter, consisted of SgnA and SgnB, is a heterodimers with inward-facing conformation. The difference between the natamycin combining efficiency of the two drug-binding cavities in SgnA/B is favorable for natamycin extracellular transport. sgnA/B gene was overexpressed in S. gilvosporeus F607 and the effects of sgnA/B gene overexpression on natamycin synthesis and extracellular transport were analyzed. In F-EX strain, the extracellular/intracellular ratio of natamycin in logarithmic synthesis stage was increased, and the total fermentation yield at 120 h was increased by 12.5% and reached to 7.38 g/L. Moreover, transcriptome sequencing analysis showed that sgnA/B gene overexpression affected the expression of genes involved in the metabolism of various amino acids, propionate, glucose, C5-branched dibasic acid and TCA cycle. This research demonstrated that the enhanced extracellular transport increased the synthesis of natamycin by S. gilvosporeus, and S. gilvosporeus F-EX showed good potential for the industrial production of natamycin.

Structural analysis of P450 AmphL from Streptomyces nodosus provides insights into substrate selectivity of polyene macrolide antibiotic biosynthetic P450s

AmphL is a cytochrome P450 enzyme that catalyzes the C8 oxidation of 8-deoxyamphotericin B to the polyene macrolide antibiotic, amphotericin B. To understand this substrate selectivity, we solved the crystal structure of AmphL to a resolution of 2.0 Å in complex with amphotericin B and performed molecular dynamics (MD) simulations. A detailed comparison with the closely related P450, PimD, which catalyzes the epoxidation of 4,5-desepoxypimaricin to the macrolide antibiotic, pimaricin, reveals key catalytic structural features responsible for stereo- and regio-selective oxidation. Both P450s have a similar access channel that runs parallel to the active site I helix over the surface of the heme. Molecular dynamics simulations of substrate binding reveal PimD can “pull” substrates further into the P450 access channel owing to additional electrostatic interactions between the protein and the carboxyl group attached to the hemiketal ring of 4,5-desepoxypimaricin. This substrate interaction is absent in AmphL although the additional substrate -OH groups in 8-deoxyamphotericin B help to correctly position the substrate for C8 oxidation. Simulations of the oxy-complex indicates that these -OH groups may also participate in a proton relay network required for O2 activation as has been suggested for two other macrolide P450s, PimD and P450eryF. These findings provide experimentally testable models that can potentially contribute to a new generation of novel macrolide antibiotics with enhanced antifungal and/or antiprotozoal efficacy.

Genome Sequence-Guided Finding of Lucensomycin Production by Streptomyces achromogenes Subsp. streptozoticus NBRC14001.

Information on microbial genome sequences is a powerful resource for accessing natural products with significant activities. We herein report the unveiling of lucensomycin production by Streptomyces achromogenes subsp. streptozoticus NBRC14001 based on the genome sequence of the strain. The genome sequence of strain NBRC14001 revealed the presence of a type I polyketide synthase gene cluster with similarities to a biosynthetic gene cluster for natamycin, which is a polyene macrolide antibiotic that exhibits antifungal activity. Therefore, we investigated whether strain NBRC14001 produces antifungal compound(s) and revealed that an extract from the strain inhibited the growth of Candida albicans. A HPLC analysis of a purified compound exhibiting antifungal activity against C. albicans showed that the compound differed from natamycin. Based on HR-ESI-MS spectrometry and a PubChem database search, the compound was predicted to be lucensomycin, which is a tetraene macrolide antibiotic, and this prediction was supported by the results of a MS/MS analysis. Furthermore, the type I polyketide synthase gene cluster in strain NBRC14001 corresponded well to lucesomycin biosynthetic gene cluster (lcm) in S. cyanogenus, which was very recently reported. Therefore, we concluded that the antifungal compound produced by strain NBRC14001 is lucensomycin.

Advances in the biosynthesis of natamycin and its regulatory mechanisms

Natamycin is a polyene macrolide antibiotics with strong and broad spectrum antifungal activity. It not only effectively inhibits the growth and reproduction of fungi, but also prevents the formation of some mycotoxins. Consequently, it has been approved for use as an antifungal food preservative in most countries, and is also widely used in agriculture and healthcare. Streptomyces natalensis and Streptomyces chatanoogensis are the main producers of natamycin. This review summarizes the biosynthesis and regulatory mechanism of natamycin, as well as the strategies for improving natamycin production. Moreover, the future perspectives on natamycin research are discussed.

Enhanced AmB Production in Streptomyces nodosus by Fermentation Regulation and Rational Combined Feeding Strategy.

Amphotericin B is a clinically important polyene macrolide antibiotic with a broad-spectrum antifungal activity. In this work, the addition of key precursors and differential metabolites, combined with staged fermentation process control strategies, was carried out to improve AmB production. Rationally designed addition strategies were proposed as follows: 4 mg/L isopropanol, 1 mM alanine, 1 g/L pyruvate, and 0.025 g/L nicotinamide were supplemented at 24 h. The AmB titer was ultimately enhanced to 6.63 g/L, with 28.5% increase in shake flasks fermentation. To further promote the biosynthesis of AmB, different glucose feeding strategies were investigated and the highest AmB titer (15.78 g/L) was obtained by constant speed fed-batch fermentation in a 5-L fermentor. Subsequently, compared with the batch fermentation (9.89 g/L), a novel combined feeding strategy was ultimately developed to improve the production of AmB by 85.9%, reaching 18.39 g/L that is the highest titer of AmB ever reported so far, in which the optimized components were fed at 24 h and the staged fermentation regulation strategies were used simultaneously. Moreover, the ratio of co-metabolite AmA decreased by 32.3%, from 3.1 to 2.1%. Through the detection of extracellular organic acids, the changes in α-ketoglutaric acid, pyruvate, and citric acid concentrations were identified as the most flexible metabolite nodes to further clarify the potential mechanism under different fermentation regulation strategies. These results demonstrated that the strategies above may provide new guidance for the industrial-scale production of AmB.

Alkaloids Modulate the Functioning of Ion Channels Produced by Antimicrobial Agents via an Influence on the Lipid Host.

It is widely recognized that an alteration in membrane physical properties induced by the adsorption of various drugs and biologically active compounds might greatly affect the functioning of peptides and proteins embedded in the membrane, in particular various ion channels. This study aimed to obtain deep insight into the diversity of the molecular mechanisms of membrane action of one of the most numerous and extremely important class of phytochemicals, the alkaloids. Protoalkaloids (derivatives of β-phenylethylamine, benzylamines, and colchicines), heterocyclic alkaloids (derivatives of purine, quinolysidine, piperidine, pyridine, quinoline, and isoquinoline), and steroid alkaloids were tested. We evaluated the effects of 22 compounds on lipid packing by investigating the thermotropic behavior of membrane lipids and the leakage of a fluorescent marker from unilamellar lipid vesicles. The alteration in the transmembrane distribution of the electrical potential was estimated by measuring the alkaloid induced changes in the boundary potential of planar lipid bilayers. We found that benzylamines, the chili pepper active components, capsaicin and dihydrocapsaicin, strongly affect not only the elastic properties of the lipid host, but also its electrostatics by dramatic decrease in membrane dipole potential. We concluded that the increase in the conductance and lifetime of gramicidin A channels induced by benzylamines was related to alteration in membrane dipole potential not to decrease in membrane stiffness. A sharp decrease in the lifetime of single ion pores induced by the antifungal lipopeptide syringomycin E, after addition of benzylamines and black pepper alkaloid piperine, was also mainly due to the reduction in dipole potential. At the same time, we showed that the disordering of membrane lipids in the presence of benzylamines and piperine plays a decisive role in the regulation of the conductance induced by the antifungal polyene macrolide antibiotic nystatin, while the inhibition of steady-state transmembrane current produced by the antimicrobial peptide cecropin A was attributed to both the dipole potential drop and membrane lipid disordering in the presence of pepper alkaloids. These data might lead to a better understanding of the biological activity of alkaloids, especially their action on voltage-gated and mechanosensitive ion channels in cell membranes.

Fungal elicitor-induced transcriptional changes of genes related to branched-chain amino acid metabolism in Streptomyces natalensis HW-2.

Natamycin is a polyene macrolide antibiotic and widely used as a natural food preservative. Fungal elicitor had positive effects on the natamycin biosynthesis in Streptomyces natalensis HW-2. However, the global gene expression in response to fungal elicitor is not still reported. In the study, RNA-Seq was used to check the change of transcriptome by fungal elicitor in S. natalensis HW-2. The results showed that there were 1265 differential expression genes (DEGs) at 40h and 2196 DEGs at 80h. Most of the genes involved in natamycin biosynthesis were upregulated. KEGG pathway analysis showed that fungal elicitor had strong effects on the transcriptional levels of genes related to branch-chained amino acid (BCAA) metabolism. There were 23 upregulated or downregulated DEGs involved in BCAA biosynthesis and degradation at 40h and 80h. To confirm whether the improvement of BCAA biosynthesis could produce more natamycin, metabolic engineering was used to homologously overexpress the gene ilvH which encoded the regulatory subunit of acetolactate synthase (ALS) in S. natalensis. The results showed that overexpression of ilvH in S. natalensis HW-2 increased natamycin production to 1.25g/L in the flask, which was a 32% increase compared with that of the parent strain. Real-time quantitative PCR analysis showed that the transcriptional level of ilvH in mutant strain S. natalensis ZS101 was significantly increased. Acetyl-CoA content was also raised. The results suggested that the fungal elicitor enhanced natamycin biosynthesis by improving precursor supply via BCAA metabolism. This study will open a new avenue for enhancing natamycin production by metabolic engineering and adding fungal elicitor. KEY POINTS: • The fungal elicitor had strong effects on the transcriptional levels of genes related to branch-chained amino acid metabolism by RNA-Seq. • The homologous overexpression of gene ilvH increased natamycin production by 32% and acetyl-CoA content was raised in mutant strain S. natalensis ZS101.