Metabolic engineering of thermophilic Bacillus methanolicus for riboflavin overproduction from methanol.

Vivien Jessica Klein, Luciana Fernandes Brito, Fernando Perez-Garcia, Trygve Brautaset, Marta Irla

Microbial biotechnology 2023 May

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The growing need of next generation feedstocks for biotechnology spurs an intensification of research on the utilization of methanol as carbon and energy source for biotechnological processes. In this paper, we introduced the methanol-based overproduction of riboflavin into metabolically engineered Bacillus methanolicus MGA3. First, we showed that B. methanolicus naturally produces small amounts of riboflavin. Then, we created B. methanolicus strains overexpressing either homologous or heterologous gene clusters encoding the riboflavin biosynthesis pathway, resulting in riboflavin overproduction. Our results revealed that the supplementation of growth media with sublethal levels of chloramphenicol contributes to a higher plasmid-based riboflavin production titre, presumably due to an increase in plasmid copy number and thus biosynthetic gene dosage. Based on this, we proved that riboflavin production can be increased by exchanging a low copy number plasmid with a high copy number plasmid leading to a final riboflavin titre of about 523 mg L-1 in methanol fed-batch fermentation. The findings of this study showcase the potential of B. methanolicus as a promising host for methanol-based overproduction of extracellular riboflavin and serve as basis for metabolic engineering of next generations of riboflavin overproducing strains. © 2023 The Authors. Microbial Biotechnology published by Applied Microbiology International and John Wiley & Sons Ltd.

Citation

Vivien Jessica Klein, Luciana Fernandes Brito, Fernando Perez-Garcia, Trygve Brautaset, Marta Irla. Metabolic engineering of thermophilic Bacillus methanolicus for riboflavin overproduction from methanol. Microbial biotechnology. 2023 May;16(5):1011-1026