Global Journal of Medical Research: C Microbiology and Pathology Volume 17 Issue 2 Version 1.0 Year 2017 Type: Double Blind Peer Reviewed International Research Journal Publisher: Global Journals Inc. (USA) Online ISSN: 2249-4618 & Print ISSN: 0975-5888 Optimization of Citric Acid Production by Substrate Selection using Gamma Ray Induced Mutant Strain of Aspergillusniger By Shamima Nasrin, Mejbah Uddin Unsary & Md. Khorshed Alam Jahangir Nagar University Abstract- The worldwide demand for citric acid is increasing with the rising population and industrialization. The growing demand for citric acid and the need for alternative materials as substrates in the recent years have led to the choice of a novel and economically viable substrate, namely jackfruit (outer portion) and molasses for citric acid biosynthesis. Hydrolysis these substrates with 0.05N HCl followed by fermentation using two isolates of Aspergillus niger were investigated for citric acid production under submerged culture condition in a period of 15 days. The products of the microbial metabolism namely residual sugar, total titratable acidity (TTA), citric acid, and biomass contents were determined periodically. Maximum citric acid production was found after 12 days of fermentation for both isolates, namely Aspergillus niger CA16, the parent strain and gamma ray induced mutant Aspergillus niger 79/20. Citric acid production was found highest in the absence of Prescott salt by Aspergillus niger CA16 in mixed fermentation medium which was about 16.35 mg/ml and lowest in jackfruit medium, 12.88 mg/ml at day 12. Whereas in the presence of Prescott salt, lowest citric acid production was also found in jackfruit medium, 7.21 mg/ml and highest in mixed medium, 11.54 mg/ml. In case of the previously isolated gamma-ray induced mutant Aspergillus niger 79/20, the yield seems to be higher under similar experimental condition. Keywords: aspergillus niger 79/20, citric acid, titratable acidity. GJMR-C Classification: NLMC Code: QW 4 OptimizationofCitricAcidProductionbySubstrateSelectionusingGammaRayInducedMutantStrainofAspergillusniger Strictly as per the compliance and regulations of: © 2017. Shamima Nasrin, Mejbah Uddin Unsary & Md. Khorshed Alam. This is a research/review paper, distributed under the terms of the Creative Commons Attribution-Noncommercial 3.0 Unported License http://creativecommons.org/ licenses/by- nc/3.0/), permitting all non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Optimization of Citric Acid Production by Substrate Selection using Gamma Ray Induced Mutant Strain of Aspergillusniger Shamima Nasrin α, Mejbah Uddin Unsary σ & Md. Khorshed Alam ρ Abstract- The worldwide demand for citric acid is increasing worldwide demand for citric acid is met by fermentation with the rising population and industrialization. The growing mainly by the process involving the filamentous fungus demand for citric acid and the need for alternative materials as A. niger. A number of carbon sources may be used for 2017 substrates in the recent years have led to the choice of a novel citric acid fermentation. For commercial reasons, the and economically viable substrate, namely jackfruit (outer uses of molasses, sucrose or glucose syrups are Year portion) and molasses for citric acid biosynthesis. Hydrolysis favored. The use of molasses in particular is desirable these substrates with 0.05N HCl followed by fermentation 23 using two isolates of Aspergillus niger were investigated for because of its low cost availability. citric acid production under submerged culture condition in a A. niger is capable of producing very high levels period of 15 days. The products of the microbial metabolism of citric acid, about 90% of the theoretical yield from a namely residual sugar, total titratable acidity (TTA), citric acid, carbohydrate source. For an efficient citric acid and biomass contents were determined periodically. Maximum production, the growth of Aspergillus in pellet form is citric acid production was found after 12 days of fermentation desirable and this can be achieved by process for both isolates, namely Aspergillus niger CA16, the parent optimization. There is a great worldwide demand for strain and gamma ray induced mutant Aspergillus niger 79/20. Citric acid production was found highest in the absence of citric acid consumption due to its low toxicity compared Prescott salt by Aspergillus niger CA16 in mixed fermentation with other acidulants used mainly in the pharmaceutical medium which was about 16.35 mg/ml and lowest in jackfruit and food industries. Global production of citric acid has medium, 12.88 mg/ml at day 12. Whereas in the presence of now reached 1.4 million tones and there is annual Prescott salt, lowest citric acid production was also found in growth of 3.5–4.0 % in demand/consumption. A high jackfruit medium, 7.21 mg/ml and highest in mixed medium, rate of acidogenesis in A. niger is observed only under Volume XVII Issue II Version I 11.54 mg/ml. In case of the previously isolated gamma-ray conditions of high glycolytic metabolism and can be ) DD D induced mutant Aspergillus niger 79/20, the yield seems to be D C induced by the addition of an excess amount of sucrose higher under similar experimental condition. In absence of ( or other carbohydrates which induce a high rate of Prescott salt highest production of citric acid was found by mutant Aspergillus niger 79/20 in mixed fermentation medium glycolytic catabolism. In this production technique, which was about 25.87 mg/ml and lowest in jackfruit medium, which is still the major industrial route to citric acid used 22.12 mg/ml at the day 12 which was even higher than that today, cultures of Aspergillus niger are fed on a sucrose found in case of the parent strain Aspergillus niger CA16. In or glucose-containing medium to produce citric acid. the presence of Prescott salt highest production of citric acid The source of sugar is corn steep liquor, molasses, was found in mixed media, 16.35 mg/ml and lowest in jackfruit hydrolyzed corn starch or other inexpensive sugary medium, 13.94 mg/ml which was again higher than that was solutions. Bangladesh, at present, imported cent Research Medical obtained in case of the parent strain. percent citric acid from foreign countries. High Keywords: aspergillus niger 79/20, citric acid, titratable production depends to a great extent on the strain used acidity. and its response to the composition of the medium can I. Introduction show a great deal of variability. Industrial production of this chemical by fermentation using cheap raw materials itric acid is one of the world’s largest tonnages of is helpful in economic development of our country. fermentation products. It is widely used in the Keeping in view the future requirements and also the Global Journal of Cfood beverage industries as an acidifying and availability of cheap raw material, efforts were made to flavor-enhancing agent, pharmaceutical, chemical, develop the process for citric acid fermentation, based cosmetic and other industries for applications such as on our local resources such as molasses from sugar acidulation, antioxidation, flavor enhancement, mills and outer portion of jackfruit. So the purpose of preservation, plasticizer and as a synergistic agent. The present study describes the feasibility of using raw and cheap materials such as molasses and outer portion of Authorασ : Dept. of Biochemistry & Molecular Biology, Jahangir nagar University, Savar, Dhaka-1342, Bangladesh. jackfruit for citric acid fermentation and to use parent e-mail: [email protected] strain CA16 & gamma-ray induced mutants for high Author ρ : Institute of Food & Radiation Biology, Atomic Energy citric acid yielding strain 79/20 of Aspergillus niger. Commission, Savar, Dhaka, Bangladesh. ©2017 Global Journals Inc. (US) Optimization of Citric Acid Production by Substrate Selection using Gamma Ray Induced Mutant Strain of Aspergillusniger Aspergillus niger is a haploid filamentous fungi prepared 10 times the media concentration and diluted and is a very essential microorganism in the field of as its normal strength in the experiment. biology. A. niger is cultured for the industrial production of many substances. Various strains of A. niger are used IV. Analytical Determination in the industrial preparation of citric acid (E330) and At the different stages of fermentation the gluconic acid (E574) and have been assessed as culture flasks were taken out of the incubator and the acceptable for daily intake by the World Health medium was collected onto the screw cap test tubes by Organization. A. niger is important because of its pipetting and preserved at 0oC. The appropriate amount involvement in producing citric acid as well as industrial of sample was used for the estimation of total titratable enzymes, such as amylases, proteases, and lipases. acidity, citric acid and amount of residual sugar present The uses of these enzymes are essential because of its in the medium after fermentation. importance for transformation to food enzymes. For example, A. niger glucoamylase is used in the V. Determination of total Titratable 2017 production of high fructose corn syrup, and pectinases Acidity (TTA) are used in cider and wine clarification. Glucose oxidase Year is used in the design of glucose biosensors, due to its Fermented medium (0.25ml) was diluted with 20ml of distilled water and was titrated against 0.1N 24 high affinity for β-D-glucose. A variety of carbohydrate sources such as beet molasses, cane molasses, NaOH solution using 2 to 3 drops of phenolphthalein as sucrose, commercial glucose, starch hydrolysates etc., indicator. The value obtained was multiplied by 4 and have been used for citric acid production. Among these, total titratable acidity was expressed as ml of 0.1N sucrose, cane and beet molasses have been found to NaOH required to neutralize 1ml fermented medium. be the best choice (Kapoor et al., 1982). The titrametric analysis of fermentation of each strain gave an indication of total acidity of the medium.