Carbon sources to enhance the biosynthesis of useful secondary metabolites in Fusarium verticillioides submerged cultures

Abstract

Fusarium verticillioides is a prolific producer of useful secondary metabolites such as naphthoquinone pigments, monoterpenes, and sesquiterpenes, as well as the harmful mycotoxins fumonisins. A strategy to increase their production includes creating a proper nutritional environment that enables the fungus to produce the compounds of interest. The aim of the present work was to study the effect of different carbon sources (glucose, fructose, xylose, sucrose, and lactose) on secondary metabolites biosynthesis in F. verticillioides submerged cultures. The production of volatile terpenes was evaluated through gas chromatography coupled to mass spectrometry. The quantification and identification of pigments was conducted using a UV/VIS spectrophotometer and NMR spectrometer, respectively. The quantification of fumonisin B1 and fumonisin B2 was performed by high-performance liquid chromatography. Our results showed that the biosynthesis of naphthoquinone pigments, monoterpenes, and sesquiterpenes was highest in cultures with fructose (13.00 ± 0.71mmol/g), lactose [564.52 × 10-11 ± 11.50 × 10-11μg/g dry weight (DW)], and xylose (54.41 × 10-11 ± 1.55 × 10-11μg/g DW), respectively, with fumonisin being absent or present in trace amounts in the presence of these carbon sources. The highest biosynthesis of fumonisins occurred in sucrose-containing medium (fumonisin B1: 7.85 × 103 ± 0.25 × 103μg/g DW and fumonisin B2: 0.38 × 103 ± 0.03 × 103μg/g DW). These results are encouraging since we were able to enhance the production of useful fungal metabolites without co-production with harmful mycotoxins by controlling the carbon source provided in the culture medium.