The kinetics of riboflavin secretion by Eremothecium ashbyii nrrl 1363

For riboflavin production a highly flavinogenic strain Eremothecium ashbyii is used. Vitamins are classified as chemical substances that control and effect the physiological processes; Riboflavin is one among them. The deficiency of riboflavin in human beings results in the cracking of lips and corners of mouth (cheilosis); nerve tissues are affected. For riboflavin production a highly flavinogenic strain Eremothecium ashbyii NRRL 1363 was used. Investigations were conducted in shake flask using inexpensive and abundantly available raw materials. Among the stimulants, a combination of hog casings and beef extract stimulated the highest and promoted the maximum riboflavin yield followed by the combination of fish meal and beef extract. The fermented broth (an enriched, riboflavin concentrate) can be directly used as a feed grade riboflavin. To upgrade it to pharmaceutical grade further investigations are required.     

Effect of pH on exocellular riboflavin production byEremothecium ashbyii

Summary The production of riboflavin byEremothecium ashbyii grown in a chemically defined medium in batch culture was affected by pH of the medium. Highest yields were obtained at constant pH of 4.5 and 5.5, while little or no riboflavin was detected at either pH 3.5 or 8.5. The medium pH also affected cell morphology. When the organism was grown in a stirred tank reactor and an airlift vessel at pH 4.5 very similar levels of riboflavin were obtained.     

Application of agro-industrial by-products for riboflavin production by Eremothecium ashbyii NRRL 1363

Riboflavin production is significantly determined by the type and initial concentration of the carbon and nitrogen sources and also by other flavinogenic stimulants. Using an optimum carbon and nitrogen concentration, an industrial fermentation medium has been designed with molasses as the carbon source and peanut seed cake as the nitrogen source. In addition the stimulatory effect of some of the low-cost agro-industrial by-products on riboflavin yield was investigated. Received: 10 March 1996 / Received revision: 25 June 1996 / Accepted: 14 July 1996     

Statistical optimization of medium components for improved synthesis of riboflavin by Eremothecium ashbyii

Statistical designs were used to determine optimum levels of medium nutrients for riboflavin production in shake flask fermentation. The medium components considered include molasses, sesame seed cake (SSC), yeast extract, KH₂PO₄, MgSO₄·7H₂O, NaCl and Tween-80. Information about the effects of different medium components on riboflavin production were investigated by using the Plackett-Burman experimental design. MgSO₄·7H₂O and NaCl were found to significantly influence the riboflavin production (confidence levels above 70%). For obtaining the mutual interaction between the variables required, for achieving the optimal concentrations, a 2²-factorial central composite design was employed. The optimal concentrations for the enhanced production of riboflavin were (g/l): molasses =50.0 (glucose equivalents); SSC =50.0; yeast extract =2.0; KH₂PO₄=2.0; MgSO₄·7H₂O=0.117 and NaCl =1.13.     

Influence of type and concentration of flavinogenic factors on production of riboflavin by Eremothecium ashbyii NRRL 1363

A study was conducted to determine the effect of various low cost organic wastes as flavinogenic factors and the various concentrations at which they induced flavinogenecity resulting in higher yields of riboflavin. A high-yielding riboflavin strain; Eremothecium ashbyii NRRL 1363 was chosen to determine the flavinogenicity. Carbon source at 50 g l(-1) (dextrose equivalents) of molasses and nitrogen source at 50 g l(-1) (weight/volume) of peanut seed cake were found to be optimal levels to yield higher riboflavin. Among the organic wastes, (beef extract, hog casings, blood meal, fish meal) hog casings in association with fish meal supported the highest yield of riboflavin. Among the different recovery processes studied, a vacuum drying process was the most efficient allowing maximum yield, followed by drying at 90 degrees C and freeze-drying. It is apparent from this study that inexpensive or waste organic materials could induce E. ashbyii to synthesize and secrete riboflavin at higher levels in the medium and this could be purified using a vacuum drying process. This bioconversion process allows us to recycle the biomaterials and produce a value-added product of economic importance.     

Comparative study of riboflavin production from two microorganisms: Eremothecium ashbyii and Ashbya gossypii

The conversion of the various substrates to riboflavin via fermentation by Eremothecium ashbyii and Ashbya gossypii was investigated. Optimum operation temperature and initial pH of the medium were determined as 30°C and 6.5 respectively for both microorganisms. In order to examine the effects of different substrates and their initial concentrations, glucose, glycerol, sunflower oil, whey and various combinations of these were utilized in the experiments. Maximum specific growth rates and riboflavin yields were obtained in the media which contained glucose and sunflower oil together as the substrate.