ISSN 2410-7751 (Print)
ISSN 2410-776X (Online)
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Biotechnologia Acta Т. 19, No. 4, 2026
P.  , Bibliography  , Engl.
UDC  663.16:577.164.12
doi: https://doi.org/10.15407/biotech

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REGULATION OF METABOLIC PATHWAYS TO ENHANCE RIBOFLAVIN BIOSYNTHESIS IN EREMOTHECIUM ASHBYI

Z. S. Shopova (https://orcid.org/0000-0002-6449-9483)
V. Yu. Polishchuk (https://orcid.org/0000-0002-1284-584X)

National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute"

Riboflavin is one of the most important water-soluble vitamins involved in numerous biochemical processes in living organisms. It serves as a precursor of the coenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), which are essential cofactors for enzymes involved in the electron transport chain, redox reactions, and the metabolism of amino acids, lipids, and carbohydrates. Currently, riboflavin is produced industrially using biotechnological approaches, including fermentation with the ascomycete Eremothecium ashbyi. However, the development of novel strategies to enhance riboflavin biosynthesis in natural producers remains an important research objective.

Aim. To investigate a novel approach to enhancing the riboflavin biosynthetic capacity of E. ashbyi by modulating its metabolic pathways using itaconic acid and ultraviolet (UV) radiation.

Methods. The E. ashbyi F-340 strain was modified by cultivation on GPDA medium supplemented with varying concentrations of itaconic acid (25–100 mM), followed by exposure to UV radiation. The cultures were subsequently cultivated on GPD medium supplemented with sunflower seed cake as a source of plant-derived oil. Riboflavin concentrations were determined spectrophotometrically.

Results. The experimental findings highlight the key role of isocitrate lyase in enhancing riboflavin biosynthesis under conditions of increased plant oil content in the culture medium. The addition of itaconate enabled the selection of colonies with enhanced riboflavin production. The most pronounced stimulation of riboflavin biosynthesis was achieved by combining treatment with 50 mM itaconate during strain selection with subsequent UV irradiation. Subsequent cultivation of the selected strain on medium supplemented with sunflower seed cake yielded a maximum riboflavin concentration of 511.73 mg/L, approximately 21-fold higher than the total riboflavin content of the unmodified strain cultivated on GPY medium (24.11 mg/L) and nearly twofold higher than that obtained on medium supplemented with sunflower seed cake (260.06 mg/L).

Conclusions. The obtained data demonstrate the effectiveness of combining agro-industrial waste utilization with stress-induced conditions to enhance the productivity of E. ashbyi for industrial riboflavin production.

Keywords: Eremothecium ashbyi, riboflavin, itaconate, ultraviolet radiation, glyoxylate cycle, ascomycete, biotechnology, cultivation.

© Palladin Institute of Biochemistry of the National Academy of Sciences of Ukraine, 2026