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

Does alteration of fumonisin production in Fusarium verticillioides lead to volatolome variation?

Fusarium verticillioides, a major fungal pathogen of maize, produces fumonisins, mycotoxins of global food safety concern. Control practices are needed to reduce the negative health and economic impacts of fumonisins. Therefore, we investigated volatile organic compounds (VOCs) emitted by fumonisin-producing (wild-type) and nonproducing (mutant) strains of F. verticillioides. VOC emissions were analyzed by gas chromatography-mass spectrometry following inoculation of maize kernels, and fumonisin accumulation was analyzed by high-performance liquid chromatography. Mutants emitted VOCs, including ethyl 3-methylbutanoate, that the wild type did not emit. In particular, ANOVA analysis showed significant differences between mutants and wild type for 4 VOCs which emission was correlated with absence of fumonisins. Exogenous ethyl 3-methylbutanoate reduced growth and fumonisin production in wild-type F. verticillioides, showing its potential in biocontrol. Together, our findings offer valuable insights into how mycotoxin production can impact VOC emissions from F. verticillioides and reveal a potential biocontrol strategy to reduce fumonisin contamination.

Effect of Carbon Sources on the Production of Volatile Organic Compounds by Fusarium verticillioides

The aim of the present study was to evaluate the effect of different carbon sources on the hydrocarbon-like volatile organic compounds (VOCs) of Fusarium verticillioides strain 7600 through a Principal Component Analysis approach, and to explore their diesel potential by using data from the literature. The fungus was cultivated in GYAM culture medium, and five carbon sources were evaluated: glucose, sucrose, xylose, lactose, and fructose. The VOCs were collected using a close-loop apparatus and identified through GC-MS. The same profile of 81 VOCs was detected with all treatments, but with different relative percentages among carbon sources. The production of branched-chain alkanes (30 compounds) ranged from 25.80% to 38.64%, straight-chain alkanes (12 compounds) from 22.04% to 24.18%, benzene derivatives (12 compounds) from 7.48% to 35.58%, and the biosynthesis of branched-chain alcohols (11 compounds) was from 6.82% to 16.71%, with lower values for the remaining groups of VOCs. Our results show that F. verticillioides has the metabolic potential to synthesize diesel-like VOCs. Further research should include the optimization of culture conditions other than carbon sources to increase the production of certain groups of VOCs.

Characterization of the influence of carbon sources on fum1 gene expression in the fumonisin producer Fusarium verticillioides using RT - LAMP assay

Fusarium verticillioides is one of the major fumonisin producers. The ingestion of this mycotoxin represents a risk for both human and animal health. The development of F. verticillioides is associated with environmental conditions, especially carbon sources. We developed a reliable and fast reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay and determined fum1 gene expression upon growth of two F. verticillioides strains isolated from maize and wheat in Czapek's medium containing four different sugars as sole carbon sources. Fumonisin B₁ (FB₁₎ production was determined by LC-MS/MS analysis. High growth and production of FB₁ were observed in fructose-containing medium for the strain that originated from maize. Less production of FB₁ occurred using maltose as sole carbon source for both strains. The fum1 gene expression started between 2 and 4 days of incubation, and positive signals were detected prior to the initial production of FB₁. The RT-LAMP assay was effective in the detection of fum1 gene expression at very early stages of F. verticillioides growth and allowed the prediction of FB₁ formation.