Screening for citric acid producing organisms

BACKGROUND

All aerobic organisms naturally contain the organic acid citric acid (2-hydroxy-1, 2, 3-tricarboxylic acid), which is formed during cellular respiration. It is a common metabolic intermediate product, and both plants and mammals almost always contain traces of it.

Citric acid is a common organic acid found in nature and can be found in animal bones, muscles, blood, peach, orange, pineapple, plum, pea, and lemon juices.

Carl Wilhelm Scheele, a Swedish chemist, was the one who first isolated and crystallized citric acid.

In the food, beverage, pharmaceutical, chemical, cosmetic, and other industries, this organic acid has numerous applications. To give meals and drinks their distinctive tart flavour, citrus acids are utilized. In addition to being utilized as a plasticizer and synergistic agent, it is used in industries for acidulation, anti-oxidation, emulsification, preservation, and flavour improvement. This acid is low/non-toxic, extremely soluble, biodegradable, and pleasant. It has received the GRAS (Generally Recognized as Safe) designation.

Citric acid was first created in 1880 using glycerol, and numerous syntheses using additional raw materials have subsequently been documented. Wehmer found in 1893 that certain Penicillium species could make citric acid from sugar. However, it wasn’t until World War I’s disruption of Italian citrus exports that microbial citric acid production gained commercial significance. When James Curie, an American food chemist, discovered in 1917 that some strains of the mold Aspergillus niger could manufacture citric acid effectively, Pfizer started employing this bacterium two years later.

One of the most significant organic acids created by fermentation is citric acid, which is also the most used biotechnological/biochemical product. Its 1.6 million tons of industrial production per year has a 3.5–4% yearly growth rate in demand and consumption. About 70% of the total citric acid generated worldwide is utilized in the food business, while 12% is used in medicines and the remaining 18% is used in other industries. Citric acid’s natural supply is extremely constrained compared to the expanding industrial demand. Its constant demand can only be met by biotechnological methods.

REQUIREMENTS

PROCEDURE

1. Collect soil sample from garden or any nearby place.
2. Weigh 1 gram of soil, add it to 100 ml of sterile distilled water, and shake well for 10 minutes.
3. Using above stock solution prepare serial dilution using sterile distilled water.
4. Pour the dilution sample in the Petri dish containing PDA medium, incubate at 30˚c for 3-5 days.
5. Isolate Aspergillus spp. by using a preliminary identification test of fungi.
6. The isolated Aspergillus spp. restrike on PDA medium, and incubate at 30˚c for 3-5 days.
7. Take a loopful of Aspergillus spore, mix it to 1 ml of sterile distilled water and prepare serial dilution, use 10⁸ dilutions for further procedure.
8. Prepare fermentation medium, was autoclave at 121˚c for 15 minutes.
9. Add 1 ml of spore suspension to the fermentation medium, and incubate it at 30˚c.
10. After every 1-2 hour take 1 ml of sample for estimation of citric acid concentration by titration with help of phenolphthalein indicator against 0.1M NaOH.

CONCLUSION

The study concludes that in order to isolate and screen Aspergillus spp. from soil samples for citric acid production and estimate it by the titration method.

REFERENCES

1. Ipsita Bhattacharjee and P K Baruah, “Isolation and screening of citric acid producing Aspergillus spp and optimisation of citric acid production by Aspergillus niger S-6”, IOSR Journal of environmental science, toxicology and food technology, vol. 9, issue 3 ver. 1, March 2015.
2. Michael, Macvren Dashen, Salleh Alhaji Ado, Joseph Ameh,Tarfena Amapu and Hashimu Zakari, “Screening and improvement of local isolates of Aspergillus niger for citric acid production”, Bayero Journal of Pure and Applied Sciences, Vol. 6(1), June 2013.
3. Djeneba H. Ouattara, Honoré G. Ouattara, Jacques N. Adom, Bernadette G. Goualié, Gisèle A. Koua, Ginette G. Doué and Sebastien L. Niamke, “Screening of Lactic Acid Bacteria Capable to Breakdown Citric Acid during Ivorian Cocoa Fermentation and Response of Bacterial Strains to Fermentative Conditions”, British Biotechnology Journal, Vol. 10(3), October 2015.
4. V. Maharani, D.Reeta, A. Sundaramanickam, S. Vijayalakshmi and T. Balasubramanian, “Isolation and characterization of citric acid producing Aspergillus niger from spoiled coconut”, International Journal of Current Microbiology and Applied Sciences, Vol. 3(3), 2014.
5. Gilberto Vinícius de Melo Pereira, Maria Gabriela da Cruz Pedrozo Miguel, Cíntia Lacerda Ramos, and Rosane Freitas Schwan, “Microbiological and Physicochemical Characterization of Small-Scale Cocoa Fermentations and Screening of Yeast and Bacterial Strains to Develop a Defined Starter Culture”, Applied and Environmental Microbiology, Vol. 78(15), August 2012.

Also read:

• Effect of inhibitors on enzyme activity
• Methods for purification of enzymes
• Isolation of O & H Antigen from Salmonella typhi
• Microbial Staining Methods
• Microplate based Alamar Blue Assays
• Isolation of Genomic DNA from E. coli
• Estimation of DNA and its purity check using UV spectrophotometer (A260 measurement)
• Isolation of O & H Antigen from Salmonella typhi

FAQs

Q.1   Common methods for citric acid production?

Ans.  Solid state fermentation, Submerged fermentation, Surface fermentation, etc.

Q.2   Organisms use for citric acid production?

Ans.  Aspergillus Spp., Candida Spp. And Bacillus licheniformis etc., are some examples of citric acid production organisms.

Q.3   Factors affecting for citric acid production?

Ans.  pH, temperature, nutrients concentration, environment is affecting production condition.

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