Wednesday, August 1, 2007 - 9:00 AM
S149
Improvement of vitamin B2 metabolite production in Ashbya gossypii by inverse metabolic engineering
María A. Santos, Laura Mateos, J. Antonio Uña, and J. Luis Revuelta. Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, Campus Miguel de Unamuno, Edificio Departamental, 37007 Salamanca, Spain
Vitamin B2, also known as riboflavin (E101), is an essential micronutrient with a key role in maintaining health. It is the functional component of the coenzymes FMN and FAD, and is therefore required by all flavoproteins, participating in a wide variety of cellular processes.
Vitamin B2 is synthesized from purine nucleotide GTP and ribulose 5-phosphate in a six-step pathway. In nature, vitamin B2 biosynthesis is restricted to microorganisms and plants, and biotechnological processes have been developed for industrial scale riboflavin production using some of those microorganisms, one of them is the hemiascomycete Ashbya gossypii. This fungus overproduces riboflavin when the maximum mycelial mass has been reached. Thus, in terms of vitamin production, two stages can be differentiated during A. gossypii culture: a trophic phase when riboflavin production is minimal and the growth rate increases, and a productive phase when the growth rate decreases and riboflavin is overproduced. Many physiological and morphological changes take place during the shift from the trophic to the productive phase. Various endeavours have focused on using different strategies to improve cellular properties increasing riboflavin production, including classical mutagenesis and engineering methods. In the presentation we show as trough inverse metabolic engineering we discovered a transcription factor that is involved in the regulation of purine biosynthesis pathway, riboflavin production, and trophic-phase span. The involvement of the transcription factor in different processes of the A. gossypii physiology and its implications to improve vitamin B2 or production of alternative compounds, such as folic acid, will also be briefly discussed.
Vitamin B2 is synthesized from purine nucleotide GTP and ribulose 5-phosphate in a six-step pathway. In nature, vitamin B2 biosynthesis is restricted to microorganisms and plants, and biotechnological processes have been developed for industrial scale riboflavin production using some of those microorganisms, one of them is the hemiascomycete Ashbya gossypii. This fungus overproduces riboflavin when the maximum mycelial mass has been reached. Thus, in terms of vitamin production, two stages can be differentiated during A. gossypii culture: a trophic phase when riboflavin production is minimal and the growth rate increases, and a productive phase when the growth rate decreases and riboflavin is overproduced. Many physiological and morphological changes take place during the shift from the trophic to the productive phase. Various endeavours have focused on using different strategies to improve cellular properties increasing riboflavin production, including classical mutagenesis and engineering methods. In the presentation we show as trough inverse metabolic engineering we discovered a transcription factor that is involved in the regulation of purine biosynthesis pathway, riboflavin production, and trophic-phase span. The involvement of the transcription factor in different processes of the A. gossypii physiology and its implications to improve vitamin B2 or production of alternative compounds, such as folic acid, will also be briefly discussed.
Web Page: www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=16820505