Riboflavin production by Ashbya gossypii
ABSTRACT Riboflavin is an important nutrient for humans and animals. Industrial production has shifted completely from chemical synthesis to microbial fermentation. First generation riboflavin production was improved by a combination of traditional mutagenesis and genetic engineering, and isolated strains have been used in industry. As the DNA genome of riboflavin producers has the potential to reveal new technologies, DNA microarray, proteomic and metabolic analyses have been applied to the analysis of hyper-riboflavin producers. In this review, disparity mutagenesis technology is introduced as a means of improving riboflavin production by Ashbya gossypii. DNA microarray, proteomic and metabolic analyses of this high riboflavin producer are discussed, as well as recent riboflavin production trends, costs and future improvements.
- SourceAvailable from: Eduard Kerkhoven
[Show abstract] [Hide abstract]
- "Genetic engineering of A. gossypii has allowed to increase the production of riboflavin to an industrial level (Kato and Park, 2012). Enzymes that correlate in expression levels and metabolic fluxes are potential targets for overexpression, in an attempt to direct the metabolic flux towards a desired product. "
ABSTRACT: Ashbya gossypii is a filamentous fungus that naturally overproduces riboflavin, or vitamin B2. Advances in genetic and metabolic engineering of A. gossypii have permitted the switch from industrial chemical synthesis to the current biotechnological production of this vitamin. Additionally, A. gossypii is a model organism with one of the smallest eukaryote genomes being phylogenetically close to Saccharomyces cerevisiae. It has therefore been used to study evolutionary aspects of bakers' yeast. We here reconstructed the first genome scale metabolic model of A. gossypii, iRL766. The model was validated by biomass growth, riboflavin production and substrate utilization predictions. Gene essentiality analysis of the A. gossypii model in comparison with the S. cerevisiae model demonstrated how the whole-genome duplication event that separates the two species has led to an even spread of paralogs among all metabolic pathways. Additionally, iRL766 was used to integrate transcriptomics data from two different growth stages of A. gossypii, comparing exponential growth to riboflavin production stages. Both reporter metabolite analysis and in silico identification of transcriptionally regulated enzymes demonstrated the important involvement of beta-oxidation and the glyoxylate cycle in riboflavin production. Biotechnol. Bioeng. 2013;9999: 1-9. © 2013 Wiley Periodicals, Inc.Biotechnology and Bioengineering 06/2014; 111(6). DOI:10.1002/bit.25167 · 4.13 Impact Factor
[Show abstract] [Hide abstract]
- "The disease caused is referred to as stigmatomycosis or " yeast spot disease " (Ashby and Nowell 1926). Major interest in Eremothecium species was attracted by A. gossypii as a potent overproducer of riboflavin/vitamin B 2 (Kato and Park 2012). Based on its molecular genetic tractability , Ashbya soon became a model for studies of fungal cell biology and filamentous growth (Wendland and Walther 2005). "
ABSTRACT: The genus Eremothecium belongs to the Saccharomyces complex of pre-Whole Genome Duplication (WGD) yeasts and contains both dimorphic and filamentous species. We established the 9.1 Mb draft genome of E. coryli, which encodes 4682 genes, 186 tRNA genes, and harbors several Ty3 transposons as well as more than 60 remnants of transposition events (LTRs). The initial de novo assembly resulted in 19 scaffolds, which were assembled based on synteny to other Eremothecium genomes into six chromosomes. Interestingly, we identified eight E. coryli loci that bear centromeres in the closely related species E. cymbalariae. Two of these E. coryli loci, CEN1 and CEN8, however, lack conserved DNA elements and did not convey centromere function in a plasmid stability assay. Correspondingly, using a comparative genomics approach we identified two telomere-to-telomere fusion events in E. coryli as the cause of chromosome number reduction from eight to six chromosomes. Finally, with the genome sequences of E. coryli, E. cymbalariae and Ashbya gossypii a reconstruction of three complete chromosomes of an Eremothecium ancestor revealed that E. coryli is more syntenic to this ancestor than the other Eremothecium species.Genome Biology and Evolution 05/2014; 6(5). DOI:10.1093/gbe/evu089 · 4.23 Impact Factor
[Show abstract] [Hide abstract]
- "The genome sequence is also of commercial interest, being used to identify ways to increase riboflavin production in A. gossypii (Kato and Park 2012). "
ABSTRACT: The filamentous fungus Ashbya gossypii is a cotton pathogen transmitted by insects. It is readily grown and manipulated in the laboratory and is commercially exploited as a natural overproducer of vitamin B2. Our previous genome analysis of A. gossypii isolate ATCC10895, collected in Trinidad nearly 100 years ago, revealed extensive synteny with the Saccharomyces cerevisiae genome, leading us to use it as a model organism to understand the evolution of filamentous growth. To further develop Ashbya as a model system we have investigated the ecological niche of A. gossypii and isolated additional strains and a sibling species, both useful in comparative analysis. We isolated fungi morphologically similar to A. gossypii from different plant-feeding insects of the suborder Heteroptera, generated a phylogenetic tree based on rDNA-ITS sequences, and performed high coverage short read sequencing with one A. gossypii isolate from Florida, a new species, Ashbya aceri, isolated in North Carolina, and a genetically marked derivative of ATCC10895 intensively used for functional studies. In contrast to S. cerevisiae, all strains carry four not three mating type loci, adding a new puzzle in the evolution of Ashbya species. Another surprise was the genome identity of 99.9% between the Florida strain and ATCC10895, isolated in Trinidad. The A. aceri and A. gossypii genomes show conserved gene orders rearranged by eight translocations, 90% overall sequence identity, and fewer tandem duplications in the A. aceri genome. Both species lack transposable elements. Finally, our work identifies plant-feeding insects of the suborder Heteroptera as the most likely natural reservoir of Ashbya, and that infection of cotton and other plants may be incidental to the growth of the fungus in its insect host.G3-Genes Genomes Genetics 06/2013; 3(8). DOI:10.1534/g3.112.002881 · 3.20 Impact Factor