The morphology, growth and metabolic state of Fusarium venenatum in cation modified media

McGeorge, Jeffrey (2019) The morphology, growth and metabolic state of Fusarium venenatum in cation modified media. Doctoral thesis, Northumbria University.

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Abstract

Fusarium venenatum is a filamentous ascomycete fungus that is currently used in the production of QuornTM food products. This is an important organism for research as there is scope for increasing our knowledge of the fungus in order to develop and improve production methods. This research involved investigating the morphology and metabolic responses of F. venenatum when grown in media modified in the amounts of iron and calcium, and in recycled growth medium. This type of analysis has not been attempted before in this fungus.

Methods were developed for the analysis of the intracellular metabolites and proteins using LC-MS/MS technology, along with software and database searches. Targeted analysis of amino acids by GC-MS was also carried out. The morphology of the fungus was measured using light-microscopy and software.

Increases in the length of the hyphae and decreases in branching were observed in iron-limited cultures, and the branching was increased in calcium-limited medium. These results could be significant for QuornTM production as the morphology could affect the texture and quality of the product.

In the iron-limited condition there was a downregulation of amino acid synthesis, with a 31% reduction of total amino acids without any reduction in biomass. The metabolome and proteome results revealed that many diverse pathways were affected. For example, respiration was downregulated in the iron-limited cultures but upregulated in excess iron cultures. Knowledge of changes in metabolites such as amino acids and nucleotides could lead to the development of ways to control the flavour of the product.

The growth of the fungus in recycled medium showed a significant increase in biomass, although there were changes to the morphology. This is a significant result as the use of recycled media would reduce expensive wastewater treatment, decrease waste, and a higher biomass would increase profitability.

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