Polishchuk V. Development of technology for production of riboflavin and essential oil produced by Eremothecium аshbyi Guill.

During the work, morphological and cultural peculiarities of the strain Eremothecium ashbyi F-340 have been investigated. The strain storage conditions have been investigated. Long-term storage of E. ashbyi culture (for 7 months) is possible only at room temperature. Growth dynamics of E. ashbyi strain F-340 in submerged culture follows the known regularities for periodic cultures. Exponential growth phase lasts for about 2 days; after this, growth deceleration and culture switch into stationery growth phase are observed; the latter one lasts for about 5 days of culturing, after which the culture is switched into die-off or autolysis phase. It has been established that pH decrease to 5.2 occurs during intensive strain growth; intensive riboflavin accumulation in cultural fluid and biomass is associated with pH increase to 7.8. The most intensive riboflavin accumulation occurs in stationery growth phase on culturing day 3–4, and its concentration reaches 34 mg/dm3. The second stage of riboflavin accumulation occurs on day 5 7 and is associated with culture autolysis; riboflavin content reaches 55 mg/dm3. Riboflavin is accumulated at the beginning in E. ashbyi mycelium, where it reaches the level of 8.1 10.7 mg/g of dry biomass and remains at that level until completion of culturing. Analyzing the response surfaces, we have established the composition of modified medium: optimal GFS-10 concentration for maximum riboflavin accumulation is 40 g/dm3, and concentrations of yeast extract and peptone in the medium are 10 and 1 g/dm3, respectively. Riboflavin concentration observed during culturing on modified medium in cultural fluid is 350.415 mg/dm3, which is 17 times higher than on GPY medium and 2.5 times higher than on initial medium with GFS-10. Wide range of variation of essential oil content has been shown. The highest quantity is observed in the medium containing GFS-10 (273…420 mg/dm3) as carbon source. Essential oil quantity is increased with increase of GSF concentration in the medium. Technological flow chart for concomitant production of riboflavin and essential oil production by hydrodistillation with further separation of riboflavin and essential oil isolation flows is provided. Key words: Eremothecium ashbyi, riboflavin, essential oil, inoculum, submerged culturing, nutrient media, glucose-fructose syrup, mathematical planning.