Riboflavin-overproducing strains of Lactobacillus fermentum for riboflavin-enriched bread

• Published in: Applied microbiology and biotechnology 2014-04, Vol.98 (8), p.3691-3700
• Main Authors: Russo, Pasquale, Capozzi, Vittorio, Arena, Mattia Pia, Spadaccino, Giuseppina, Dueñas, María Teresa, López, Paloma, Fiocco, Daniela, Spano, Giuseppe
• Format: Article
• Language: English
• Subjects: Agricultural biotechnology; Applied Genetics and Molecular Biotechnology; Biomedical and Life Sciences; Biotechnology; Bread; Chromatography, High Pressure Liquid; DNA Mutational Analysis; Drug Tolerance; Fermentation; Food; Food Handling - methods; Genetic aspects; Lactobacillus; Lactobacillus fermentum; Lactobacillus fermentum - drug effects; Lactobacillus fermentum - genetics; Lactobacillus fermentum - growth & development; Lactobacillus fermentum - metabolism; Life Sciences; Liquid chromatography; Metabolic Engineering; Metabolism; Microbial Genetics and Genomics; Microbiology; Microorganisms; Mutagenesis; Mutation; Older people; Physiological aspects; Riboflavin - analogs & derivatives; Riboflavin - isolation & purification; Riboflavin - metabolism; Riboflavin - toxicity; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae - metabolism; Studies; Vitamin B; Vitamin B2; Yeasts
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-013-5484-7

Lactobacillus fermentum isolated from sourdough was able to produce riboflavin. Spontaneous roseoflavin-resistant mutants were obtained by exposing the wild strain (named L. fermentum PBCC11) to increasing concentrations of roseoflavin. Fifteen spontaneous roseoflavin-resistant mutants were isolated, and the level of vitamin B 2 was quantified by HPLC. Seven mutant strains produced concentrations of vitamin B 2 higher than 1 mg L −1 . Interestingly, three mutants were unable to overproduce riboflavin even though they were able to withstand the selective pressure of roseoflavin. Alignment of the rib leader region of PBCC11 and its derivatives showed only point mutations at two neighboring locations of the RFN element. In particular, the highest riboflavin-producing isolates possess an A to G mutation at position 240, while the lowest riboflavin producer carries a T to A substitution at position 236. No mutations were detected in the derivative strains that did not have an overproducing phenotype. The best riboflavin overproducing strain, named L. fermentum PBCC11.5, and its parental strain were used to fortify bread. The effect of two different periods of fermentation on the riboflavin level was compared. Bread produced using the coinoculum yeast and L. fermentum PBCC11.5 led to an approximately twofold increase of final vitamin B 2 content.