Production and Partial Characterization of Citric Acid by Local Isolate of Aspergillus Niger Using Sorghum

Abstract

In the present study, the citric acid producing organisms were isolated from soil sample using serial dilution technique and the isolate were identified on the basis of their microscopic and morphological characteristics. The isolated fungal species were screened on the citric acid production using Czapek-Dox agar medium. From the isolates, fungal species Aspergillus niger were used for citric acid production, and the fungal species subculture using potato dextrose medium. The fresh culture of isolated Aspergillus niger were mixed to the fermentative medium along with the substrates, sorghum flour, corn starch and wheat flour separately and the fermentative medium was incubated 6-7 days at 30 0 C, after incubation the citric acid content was estimated by titrimetric method. Among the three substrates highest citric acid production was observed in corn starch supplemented medium than sorghum and wheat flour medium. Further characterization of citric acid was by paper chromatography, thin layer chromatography and IR. So it is highly recommended that the usage of corn starch supplemented medium with Aspergillus niger will be effective in the production of citric acid than the other substrates.

Citric acid production by Aspergillus niger using different substrates

“…Prasad et al (2013) showed that citric acid production was increased with 2.4 mM concentration of ammonium sulphate. Results in this study showed that concentrations above 0.25% for ammonium sulphate had higher citric acid production as compared to the positive control, which agreed with Prasad et al (2013) and Patil and Patil (2014), that ammonium sulphate increases citric acid production. Results for ammonium sulphate further contradicted with Da Silva et al (2012) who showed that 0.7 g/L of ammonium sulphate reduced citric acid production, while 0.75% concentration of ammonium sulphate in this study had positive effect on citric acid production (4.88 g/L at 144 h) as it produced more citric acid than the positive control (4.44 g/L at 168 h).…”

“…However, findings of Ali et al (2002) and Kareem et al (2010) highlighted above, were not in agreement with results for ammonium sulphate, which had maximum citric acid production at 0.5% (5.02 g/L) while the 0.25% concentration had 3.65 g/L. Patil and Patil (2014) showed that ammonium sulphate produced more citric acid than casein, sodium nitrate, yeast extract and ammonium nitrate. Prasad et al (2013) showed that citric acid production was increased with 2.4 mM concentration of ammonium sulphate.…”

“…Nitrogen has a profound effect on citric acid production as it is not only important for metabolic rates in the cells but is also a basic part of cell proteins and was shown to induce pellet formation in filamentous fungi (Ali et al, 2002). Nitrogen has been reported to be an important factor in fermentation processes due to an increase in C/N ratio (Kareem and Rahman, 2011;Patil and Patil, 2014). The present study showed that nitrogen has an effect on citric acid production using A. niger as shown by Figures 4 and 5 where the maximum citric acid production with nitrogen supplements was 5.22 g/L (0.25% after 168 h) while the positive control had a maximum of 4.4 g/L (after 168 h).…”

“…The other effect being positive as a moderate input contributes to the maintenance of citric acid productive biomass (Pintado et al, 1998). Nutritional composition of the media, environmental conditions, manganese deficiency, pH, dissolved oxygen tension, influence of different sugar types and concentrations (El-Holi and Al-Delaimy, 2003;Patil and Patil, 2014) are other factors which affect citric acid production. According to Haider (2014), citric acid production is mainly affected by ISSN (print): 1823-8262, ISSN (online): 2231-7538 cultural conditions such as carbon sources and concentration, nitrogen sources and concentration, acidity of the medium and aeration.…”

Citric Acid Production Potential of <i>Aspergillus niger</i> Using <i>Chrysophyllum albidum</i> Peel

“…The surface of the medium was point inoculated with the spores of the individual fungal isolate and incubated at 28˚C ± 2˚C for 5 -7 days. The colonies which showed yellow colour zones around them were selected as citric acid producers [12].…”