Epigenetic modification enhances ergot alkaloid production of Claviceps purpurea.

OBJECTIVE: To enhance ergot alkaloid production of Claviceps purpurea Cp-1 strain by epigenetic modification approach. RESULTS: The chemical epigenetic modifiers were screened to promote ergot alkaloid production of the Cp-1 strain. The histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA) was found to significantly enhance the alkaloid productivity of the strain. Particularly, the titers of total ergot alkaloids were gradually increased with the increase of SAHA concentration in the fermentation medium, and the highest production of ergot alkaloids could be achieved at the concentration of 500 µM SAHA. Specially, the titers of ergometrine and total ergot alkaloids were as high as 95.4 mg/L and 179.7 mg/L, respectively, which were twice of those of the control. Furthermore, the mRNA expression levels of the most functional genes in the ergot alkaloid synthesis (EAS) gene cluster were up-regulated under SAHA treatment. It was proposed that SAHA might increase histone acetylation in the EAS gene cluster region in the chromosome, which would loosen the chromosome structure, and subsequently up-regulate the mRNA expression levels of genes involved in the biosynthesis of ergot alkaloids, thereby resulting in the markedly increase in the production of ergot alkaloids. CONCLUSIONS: The ergot alkaloid production by the C. purpurea Cp-1 strain can be effectively increased by the application of histone deacetylase inhibitor. Our work provides a reference for using the chemical epigenetic modifiers to improve SM production in other fungi.

Cell volume regulation in Claviceps fusiformis. An animal-type Na,K-ATPase operating in a fungus?

Claviceps fusiformis, an ergot pathogen of pearl millet, was equilibrated in media without and with 0.1 mM ouabain (g-strophantin). Highly significant effects of ouabain on the contents of sodium ions and water were found, suggesting that an active transport of sodium ions, similar to that in animal cells, regulates the cell volume of the fungus. The basic role of the sodium pump appears to be to decrease larger cell volumes and to increase the small ones; for this purpose it can even reverse its direction.

[Effect of the composition of a nutrient medium on growth and synthesis of ergot alkaloids by Claviceps purpurea in the saprotrophic culture]. / Vliianie sostava pitatel'noi sredy na rost i sintez alkaloidov sporyn'i v saprotrofnoi kul'ture.

The impact of changes in the ratio of the medium-668 components on growth and synthesis of ergot alkaloids in saprotrophic cultures was studied with mathematical design of the experiment. Medium-668 used for cultivation of strain VNIIA-312A-producing peptide +ergot alkaloids was shown to be balanced with respect to the ratio of all the medium components. An important role of phosphate in control of culture growth and alkaloids synthesis was elucidated. It was demonstrated that by changing the ratio of the medium components it was possible to control accumulation and excretion of the alkaloids which permitted development of the conditions required for product isolation.

[Preservation of Claviceps purpurea, the producer of peptide ergot alkaloids, by the method of freeze drying]. / Konservatsiia produtsenta peptidnykh érgoalkaloidov Claviceps purpurea metodom L-vysushivaniia.

A saprotrophic strain of Claviceps purpurea VNIIA 312A, an organism producing peptide +ergot alkaloids with prolactin inhibiting activity was shown to die under lyophilization conditions. To provide long-term storage of strain 312A, L-drying or drying under vacuum from liquid state was used with success. Three protective media were tested. Favourable results were obtained by using 25 per cent maltose solution as a protective medium. Preservation of the culture viability was accompanied by maintenance of the culture capacity for active formation of the biomass and production of +ergot alkaloids.

Effect of clomiphene on fatty acids, sterols and membrane fluidity in clavine producing Claviceps purpurea strains.

Clomiphene depressed the growth and enhanced clavine production of Claviceps purpurea strains 129,35 and 59. Mycelial content of 18:2 and 16:0 fatty acids decreased, whereas that of 18:1 and 18:0 acids increased. In the mutant strain 59 clomiphene, triadimefon and ergosterol stimulated the impaired function of chanoclavine cyclase. Their effect was counteracted by plant oil. Clomiphene decreased the content of total lipids (44%), triglycerides (32%), sterols (22%) and sterol/phospholipid molar ratio. The PC/PE ratio was 9X increased. Clomiphene and triadimefon enhanced membrane fluidity of protoplasts, ergosterol and oil reverted their effect.

Influence of tryptophan and related compounds on ergot alkaloid formation in Claviceps purpurea (FR.) Tul.

L-Tryptophan did not exert any influence on peptide alkaloid formation in an ergotamine and in an ergosine-accumulating C. purpurea strain. A different picture was observed in a series of related C. purpurea strains. Tryptophan showed a slight stimulatory effect on the ergotoxine producer Pepty 695/S. A blocked mutant of it, designated as Pepty 695/ch which was able to accumulate secoclavines gave similar results. In a high-yielding elymoclavine strain Pepty 695/e, the progeny of the former one, tryptophan up to a concentration of 25 mM stimulated remarkably clavine biosynthesis. Furthermore, tryptophan could overcome the block of synthesis by inorganic phosphate. Increased specific activities of chanoclavine cyclase but not DMAT synthetase were observed in cultures of strain Pepty 695/e supplemented with tryptophan. 5-Methyltryptophan and bioisosteres of tryptophan were ineffective in alkaloid stimulation. These results are compared with those obtained with the grass ergot strain SD 58 and discussed with the relation to other induction phenomena.

[Effect of amitrol on Claviceps fusiformis, strain SD 58]. / Einfluss von Amitrol auf Claviceps fusiformis, Stamm SD 58.

The influence of amitrole (3-amino-1,2,4-triazole) on growth, alkaloid formation and on some aromatic as well as ergoline pathway specific enzymes were studied in Claviceps strain, SD 58. In a phosphate-rich medium the addition of amitrole can partially reverse the alkaloid-depressing effect of phosphate. Using a typical fermentation medium amitrole reduces the activities of ergoline specific enzymes but increases drastically tryptophan synthase activity and to a lesser extent transaminase of aromatic amino acids.

A method of preparation and application of nitrous acid as a mutagen in Claviceps purpurea.

A simple and speedy procedure is described for the preparation and application of nitrous acid in mutagenic experiments. The conventional incubation mixture of sodium nitrite solution with acetate buffer is replaced by an aqueous solution of nitrous acid prepared by running a solution of sodium nitrite through a column of ion exchange. The procedure eliminates also the interference of other substances. Experimental appraisal of the technique was done during the mutagenic improval of the fungus Claviceps purpurea.