Production of bikaverin by a Fusarium fujikuroi mutant in submerged cultures

Abstract

A variety of mutants having different colony characteristics, morphology and soluble pigmentation were generated from Fusarium fujikuroi by exposure to UV radiation. Mutants were selected that formed dry, compact, small colonies with reddish-violet pigment on regeneration agar plates. The production of bikaverin by Mut-4 was examined in shake flasks in media with different nitrogen and carbon sources. The optimal C: N ratio for the maximal bikaverin production by Mut-4 was 150:1. It produced still higher bikaverin (6.3 g l−1) in a medium containing defatted cottonseed meal as nitrogen source, in combination with glucose. Bikaverin produced was extracted, purified and characterized by UV-visible and NMR spectroscopy. Bikaverin production in the present investigation was substantially higher than that reported by earlier investigators in submerged and solid-state fermentations.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-016-0205-0) contains supplementary material, which is available to authorized users.

Isolation of two novel purple naphthoquinone pigments concomitant with the bioactive red bikaverin and derivates thereof produced by Fusarium oxysporum

“…vasinfectum, on solid‐state fermentation, where production capacities were correlated to the different nutrient ratio and pH. In general, bikaverin is found in presence of smaller amounts of its precursor molecule, norbikaverin, as it has been reported for many Fusaria species, like F. fujikuroi …”

“…This was consistent with the fact, that majority of the common polyketide‐derived chromophores absorb in the UV region (one or several peaks between 200 and 300 nm). It includes the polyketide pigment carmine which absorbed in the UV region at 276 nm, the naphthoquinone pigments and hydroxyanthraquinone pigments previously isolated from Fusarium species . Examples included the red pigment bikaverin (λ max at 253 and 276 nm in UV region) and the naphthoquinone pigment O ‐methylfusarubin (λ max at 282 nm) previously isolated from F. fujikuroi …”

“…Despite the production of these polyketidic pigments during the growth of fungal strains, no direct implication of these colored compounds on the growth could be concluded. According to Medentsev and coworkers, who studied the biosynthesis of colored naphthoquinone metabolites by Fusarium graminearum, Fusarium decemcellulare, and Fusarium bulbigenum , the biosynthesis of naphthoquinone pigments in Fusarium species was shown to be the main response to environmental stresses, observed under conditions of growth inhibition or arrest …”

“…Although considerable work was performed for the isolation and structural characterization of bikaverin from F. fujikuroi, as well as for the determination of its biological activity and applications, very few reports are available regarding the characterization and regulation mechanisms of the production of other polyketidic pigments by F. oxysporum in submerged culture. All the studies performed on F. oxysporum strains have essentially focused on the biological activities of their main uncolored secondary metabolites, fusaric acid, and beauvericin.…”

“…13,14 Fusarium species have also been recognized as promising sources of colored polyketidic secondary metabolites (PK-SMs). Among them, red naphthoquinone pigments such as bikaverin, aurofusarin, fusarubin, bostrycoidin, javanicin, and novarubin [15][16][17][18][19][20][21][22][23][24][25][26] were described as the most abundant, followed by hydroxyanthraquinoic pigments (chrysophanol, catenarin, erythroglaucin, and tritisporin) (review in Caro et al 3,27 ). The polyketidic pigments produced by F. oxysporum, characterized as naphthoquinones and anthraquinones, are active against bacteria, yeast, fungi, protozoa (Leishmania brasiliensis), and insect (Calliphora erythrocephala).…”