The present investigation deals with the kinetics of submerged citric acid fermentation by Aspergillus niger using blackstrap molasses as the basal fermentation media. A laboratory scale stirred fermentor of 15-L capacity having working volume of 9-L was used for cultivation process and nutritional analysis. Among the 10 stock cultures of Aspergillus niger, the strain GCBT7 was found to enhance citric acid production. This strain was subjected to parametric studies. Major effects were caused due to oxygen tension (1.0 l/l/min), pH value (6.0) and incubation temperature (30ºC). All fermentations were carried out following the growth on 150 g/l raw molasses sugars for 144 hours. Ferrocyanide (200 ppm) was used to control the trace metals present in the molasses medium. Ammonium nitrate (0.2%) was added as nitrogen source. Maximum citric acid production (99.56 ± 3.5a g/l) was achieved by Aspergillus *Corresponding author niger GCBT7. The dry cell mass and sugar consumption were 18.5 and 96.55 g/l, respectively. The mycelia were intermediate round pellets in their morphology. The specific productivity of GCBT7 (qp = 0.074 ± 0.02a g/g cells/h) was several folds higher than other strains. The specific production rate and growth coefficient revealed the hyperproducibility of citric acid using mutant GCBT7.Citric acid fermentation is one of the rare examples of industrial fermentation technology where academic discoveries have worked in tandem with industrial knowhow, in spite of an apparent lack of collaboration, to give rise to an efficient fermentation process. The current world market estimates suggest that upwards of 4.0 x 10 5 tonnes citric acid per year may be produced (Kristiansen et al. 1999). Citric acid is a major product but the upward trend Ali, S. et al.
259in its use seen over many years is an annual 2-3% increase. The demand for this particular metabolite is increasing day by day which requires a much more efficient fermentation process for higher yield product (Moreira et al. 1996). When applied to appropriate mass balances, it is possible to predict the utilization of substrates and the yield of individual products. Fermentation media for citric acid biosynthesis should consist of substrates necessary for the growth of microorganism, primarily the carbon, nitrogen and phosphorus sources. Moreover, water and air can be included as fermentation substrates (Singh et al. 1998;Haq et al. 2001). The basic substrates for citric acid fermentation using submerged technique of fermentation are beet or cane-molasses (Pazouki et al. 2000). The present investigation deals with the kinetic study of citric acid fermentation. Cane-molasses was employed as the basal fermentation media in the stirred fermentor under the submerged fermentation conditions. The study revealed the nutritional status of the organism and basic fermentation parameters.
Materials and Methods
Organism and culture maintenanceTwelve stock cultures of Aspergillus niger were obtained from the culture collection of Biotechnology Research Laboratories...
Background: The 3,4-dihydroxy phenyl L-alanine (L-dopa) is a drug of choice for Parkinson's disease, controlling changes in energy metabolism enzymes of the myocardium following neurogenic injury. Aspergillus oryzae is commonly used for L-dopa production; however, potential improvements in ease of handling, growth rate and environmental impact have led to an interest in exploiting alternative yeasts. The two important elements required for L-dopa production are intracellular tyrosinases (thus pre-grown yeast cells are required for the transformation of Ltyrosine to L-dopa) and L-ascorbate, which acts as a reducing agent.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.