Citric acid production

Department of Chemical, Biochemical and Ecology Engineering, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, 1001 Ljubljana, Slovenia.
Biotechnology annual review 02/2007; 13:303-43. DOI: 10.1016/S1387-2656(07)13011-8
Source: PubMed


Citric acid is a commodity chemical produced and consumed throughout The World. It is used mainly in the food and beverage industry, primarily as an acidulant. Although it is one of the oldest industrial fermentations, its World production is still in rapid increasing. Global production of citric acid in 2007 was over 1.6 million tones. Biochemistry of citric acid fermentation, various microbial strains, as well as various substrates, technological processes and product recovery are presented. World production and economics aspects of this strategically product of bulk biotechnology are discussed.

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    • "In biochemistry, the conjugate base of citric acid, citrate, is important as an intermediate in the citric acid cycle, which occurs in the metabolism of all aerobic organisms. It consists of 3 carboxyl (R-COOH) groups (Berovic et al., 2007). The basic substrates for citric acid fermentation using submerged technique of fermentation are beet or cane molasses (Pazouki et al., 2000). "
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    ABSTRACT: Citric acid (CH2COOH.COH.COOH.CH2COOH) is a tricarboxylic acid, soluble in water with a pleasant taste; it is an important acid used in food Industries. It exists in nature when carbohydrates are oxidized to carbon dioxide. Because of its high solubility, palatability and low toxicity it can be used in food, biochemical, and pharmaceutical industries. The aims of this study are citric acid production from fungi (Aspergillus niger) using by-product of sugar (sugarcane molasses) and to evaluate its concentration. Indigenous strains of A. niger were isolated from soil (depth 15cm), air and bread and identified using ordinary medium Sabouraud's dextrose agar medium supplemented with Rose Bengal. A pure culture of tested microorganisms were inoculated into different flasks containing different concentrations of molasses and incubated for 144 hrs at 28°C. The production of citric acid determined by the appearance of air bubble and colour's change; the mixtures were distilled at 175ºC for one and half hr. After the distillation process; the citric acid was detected and titrated to determine its percentage by adding bromocryesol green and NaOH (N 0.1), respectively. Citric acid production from the soil sample was of high amount, when compared with air, and bread. The soil sample produced 9.6 % of citric acid compared with air 6.7% and bread 7.7 %. The maximum citric acid production was produced on the 6th day of fermentation in all samples. By recycling and reusing waste material from cane molasses citric acid production can be easily achieved by using microorganisms that have the ability to produce citric acid efficiency such as Aspergillus niger.
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    • "This is because of their mechanical simplicity, low capital cost, and good heat and mass transfer characteristics [1]. Products produced using bubble columns include baker's yeast (Saccharomyces cerevisiae) [2], citric acid [3] [4] and amino acids [5] [6] [7]. Bubble columns used as bioreactors typically operate in the heterogeneous flow regime, i.e. at superficial velocities greater than 0.05 m/s [8]. "
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    ABSTRACT: We have examined the effect of superficial velocity, tracer injection location and measurement location on the mixing time in a bubble column. It was found that for the range of superficial velocities examined (0.07-0.29 m/s) there was little change in mixing time with superficial velocity. In contrast, it was found that the tracer injection point and measurement location had a large impact on the measured mixing time, with measured values ranging between 3 s and 25 s. Additionally, it was found that it was possible to introduce the tracer in such a way as to produce zones of poor mixing, leading to a high local tracer concentration. Such a finding is important in the design of bubble columns used in the bio-processing industry as these conditions can lead to a reduction in the yield of industrial bioprocesses. The second half of this work examines the use of Computational Fluid Dynamics (CFD) as a tool to model mixing in bubble columns. It was found that a computationally efficient CFD model correctly predicted the trends in mixing time for all superficial velocities and tracer addition locations examined, with the model being able to correctly predict the mixing time within the margin of variation.
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    • "Fungi are not only producers of drugs, but are also industrially exploited to produce enzymes or food additives. For example, Aspergillus niger is used for large-scale fermentation of citric acid and gluconic acid (Berovic and Legisa 2007; Singh and Kumar 2007). In Asian cuisine, Aspergillus oryzae is used for fermentation of soybeans, saccharification of rice, and production of alcoholic drinks and rice vinegars (Kobayashi et al. 2007). "
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    ABSTRACT: Fungal genomics revealed a large potential of yet-unexplored secondary metabolites, which are not produced during vegetative growth. The discovery of novel bioactive compounds is increasingly gaining importance. The high number of resistances against established antibiotics requires novel drugs to counteract increasing human and animal mortality rates. In addition, growth of plant pathogens has to be controlled to minimize harvest losses. An additional critical issue is the post-harvest production of deleterious mycotoxins. Fungal development and secondary metabolite production are linked processes. Therefore, molecular regulators of development might be suitable to discover new bioactive fungal molecules or to serve as targets to control fungal growth, development, or secondary metabolite production. The fungal impact is relevant as well for our healthcare systems as for agriculture. We propose here to use the knowledge about mutant strains discovered in fungal model systems for a broader application to detect and explore new fungal drugs or toxins. As examples, mutant strains impaired in two conserved eukaryotic regulatory complexes are discussed. The COP9 signalosome (CSN) and the velvet complex act at the interface between development and secondary metabolism. The CSN is a multi-protein complex of up to eight subunits and controls the activation of CULLIN-RING E3 ubiquitin ligases, which mark substrates with ubiquitin chains for protein degradation by the proteasome. The nuclear velvet complex consists of the velvet-domain proteins VeA and VelB and the putative methyltransferase LaeA acting as a global regulator for secondary metabolism. Defects in both complexes disturb fungal development, light perception, and the control of secondary metabolism. The potential biotechnological relevance of these developmental fungal mutant strains for drug discovery, agriculture, food safety, and human healthcare is discussed.
    Full-text · Article · Aug 2014 · Applied Microbiology and Biotechnology
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