Antagonistic effect of myo-inositol on riboflavin production in two riboflavinogenic fungi Ashbya gossypii and Eremothecium ashbyi

Ashbya gossypii and Eremothecium ashbyi are riboflavin over producing fungi. Guanosine tri-phosphate (GTP) cyclohydrolase II, encoded by RIB1 gene, catalyses the rate limiting step of the riboflavin biosynthetic pathway. We report here the antagonistic effect of myo-inositol on riboflavin production in these two fungi by adapting them in Yeast Malt Agar (YMA) media containing 0.1% inositol. The adapted E. ashbyi showed 92% reduction and the adapted Ashbya showed 39% increase in the total riboflavin production, when compared to that produced by E. ashbyi and Ashbya respectively. Reverse transcription-polymerase chain reaction (RT-PCR) study indicated that myo-inositol reduced RIB1 gene expression in adapted E. ashbyi but enhanced the same in adapted Ashbya.

► Addition of 0.1% inositol in YM media, reduced riboflavin production by 92% in E. ashbyi.
► Addition of 0.1% inositol in YM media, enhanced riboflavin production by 39% in A. gossypii.
► Inositol reduced RIB1 gene expression in adapted E. ashbyi but enhanced that in adapted Ashbya.