Citric acid production from glucose by yeast Candida oleophila ATCC 20177 under batch, continuous and repeated batch cultivation (original) (raw)
Related papers
World Journal of Microbiology and Biotechnology, 2005
The central aspect of this work was to investigate the influence of nitrogen feed rate at constant C/N ratio on continuous citric acid fermentation by Candida oleophila ATCC 20177. Medium ammonia nitrogen and glucose concentrations influenced growth and production. Space-time yield (STY) meaning volumetric productivity, biomass specific productivity (BSP), product concentration, product selectivity and citrate/isocitrate ratio increased with increasing residence time (RT). BSP increased in an exponential mode lowering nitrogen feed rates. Highest BSP for citric acid of 0.13 g/(g h) was achieved at lowest NH 4 Cl concentration of 1.5 g/l and highest STY (1.2 g/l h) with 3 g NH 4 Cl/l at a RT of 25 h. Citric acid 74.2 g/l were produced at 58 h RT and 6 g NH 4 Cl/l. Glucose uptake rate seems to be strictly controlled by the growth rate of the yeast cells. Optimum nitrogen concentration and adapted C/N ratio are essential for successful continuous citric acid fermentation. The biomass-specific nitrogen feed rate is the most important factor influencing continuous citric acid production by yeasts. Numerous chemostat experiments showed the feasibility of continuous citrate production by yeasts.
Citric Acid Production of Yeasts: An Overview
The EuroBiotech Journal
Background Citric acid, an intermediate product of the Krebs cycle, has a wide usage area in the food industry since it has some functions such as acidulant, flavouring agent, preservative and antioxidant. Although molds are the most commonly used microorganisms in the citric acid production, it is known that there are significant advantages of using yeasts. Purpose and scope The microbial citric acid production mechanism needs to be well understood to make production more efficient. In this study, the yeasts used in the production, fermentation types and the factors affecting production were reviewed with studies. Methodology Although production of citric acid can be produced by chemical synthesis, the fermentation is preferred because of its low cost and ease of use. More than 90% of citric acid produced in the world is obtained by fermentation. Results Yarrowia lipolytica, Candida zeylanoides and Candida oleophila are evaluated for citric acid production with substrates such as m...
Citric acid is the most important organic acid produced by fermentation, widely used in food, pharmaceutical and chemical industries. Although Aspergillus niger is the traditional producer of citric acid, during the last 30 years the interest of researchers has been attracted by the use of yeasts for citric acid fermentation processes. Among the yeast species, Yarrowia lipolytica is known as a potential producer of citric acid. Environmental factors that have been shown to exert an effect on citric acid production are the type and concentration of carbon source of the fermentation medium, nitrogen and phosphate limitations, aeration, trace elements, initial pH and temperature. Besides the regulation of product formation by environmental conditions, strain selection and improvement has become the important factor. The improvement of citric acid producing yeast strains has been carried out by mutagenesis and selection. Because of annual growths in demand of citric acid, using alternative processes and strains for its production are in progress.
2016
Citric acid production by fermentation is the most widely used way of obtaining it. The effects of some medium components were evaluated for Citric acid fermentation during the 1930s and 1940s.This work aimed to optimize citric acid by Candida tropicalis under submerged fermentation conditions using Plackett-Burman design. Some factors were tested as main variables affecting citric acid production using Plackett-Burman design. The results showed that incubation period of 7 days and pH 7; sodium acetate (10g/L), magnesium sulfate (1.5g/L), potassium phosphate (5g/L), ammonium chloride (3g/L), ferric sulfate(140mg/L), manganese sulfate (50 mg/L), zinc sulfate (80 mg/L), yeast extract (5.0g/L), glucose (150g/L), aeration ratio (75ml medium/ flask 250ml) were the most effective conditions for the highest yield of citric acid. The highest citric acid concentration was 30.0 g/L of the medium under the aforementioned conditions.
Optimization of Citric Acid Production by Immobilized Cells of Novel Yeast Isolates
Mycobiology, 2020
Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an $52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBankbased sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 C, with NH 4 Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 C with (NH 4) 2 SO 4 as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.
Bioprocess Engineering, 2000
Citric acid production by Aspergillus niger NCIM 548 and Candida lipolytica NCIM 3472 has been studied in shake culture using glucose and molasses as carbon sources. Methanol addition (3% v/v) at 40 h of fermentation enhanced the production of citric acid by Aspergillus niger whereas a reduction in citric acid production by Candida lipolytica was observed with addition of methanol. Maximum citric acid concentration of 12 kg/ m 3 was obtained with Aspergillus niger using molasses in the presence of methanol, while maximum citric acid concentration of 8.4 kg/m 3 was obtained with Candida lipolytica using glucose without methanol. It appears that product formation by Aspergillus niger is either nongrowth associated or partially growth associated depending on the substrate. Methanol addition changes the nature of product formation in case of Candida lipolytica.
Citric Acid Production Fermentation Process
International Journal of Advance Research and Innovative Ideas in Education, 2017
Citric acid is the most important organic acid produced in tonnage and is extensively used in food and pharmaceutical industries. It is produced mainly by submerged fermentation using Aspergillus niger or Candida sp. from different sources of carbohydrates, such as molasses and starch based media. However, other fermentation techniques, e.g. solid state fermentation and surface fermentation, and alternative sources of carbon such as agroindustrial residues have been intensively studied showing great perspective to its production. This paper reviews recent developments on citric acid production by presenting a brief summary of the subject, describing microorganisms, production techniques, and substrates, etc.
An overview of citric acid production
This article reviews the present state of research on the conversion of low cost substrates to citric acid by fermentation. Fermentation is a powerful incentive for semi-industrialized countries. There is a great demand for citric acid due to its wide industrial applications and less toxicity. Citric acid can be produced using less expensive substrates that are renewable too. Plant biomass is one of the desirable raw materials for fermentation due to its availability in abundance. Using natural sources as substrates we can minimize environmental problems. Always species of Aspergillus and Candida remain the choice of candidates for the biosynthesis of citric acid. A concise gist of the various natural sources that can be used for the production of citric acid along with the necessary fermentation conditions is presented.
Biotechnology Letters
In this study, citric acid production by autochthonous Candida zeylanoides 7.12 was investigated and optimized. Response surface methodology (RSM) was used for the analysis of simultaneous effects of the chosen factors and two experiment designs were applied. In the rst experimental design, the effects of initial pH value (5.5-6.5), fermentation time (4-6 days) and initial glucose concentration (125-175 g/L) on citric acid production were investigated. Initial pH value was adjusted periodically with NaOH. Results of the statistical analysis showed that the model was found to be not applicable su ciently to the chosen data. A second experimental design was employed by keeping the pH constant at pH 6.5 using glucose concentration and fermentation time as the process parameters to be optimized. Results of the statistical optimization showed that the t of the model was good and the lack of t was not signi cant at the 5 % (P<0.05). The highest citric acid concentration of 11.36 g/L was obtained after 6 days of fermentation with an initial glucose concentration of 125 g/L. The results indicated that initial glucose concentration and fermentation time were important parameters for citric acid production by C. zeylanoides 7.12 and this strain could be used for future studies.