Citric Acid Production by Aspergillus niger and Aspergillus awamori Isolated from Soil in keffi, Nigeria
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Abstract
Citric acid is an Organic acids, commercially valuable product extensively used in different industries for various purposes. This study aimed at citric acid production by A.niger and A. awamori isolated from soil in Keffi using waste starch from corn milling factory. A.niger and A. awamori was isolated from soil in Keffi and identified using standard microbiology methods. Starch production media was prepared by following standard fermentation conditions. The citric acid produced was estimated using Gas Chromatography/Mass Spectrometry (GC/MS) method. The occurrence of Aspergillus species showed that Pyanku had the highest percentage occurrence with 100%. The screening for citric acid producing A.nigerand A. awamori showed that isolates from location A, C and D showed ability to produce citric acid. Effect of different temperature on citric acid production showed that A.awamoriA1produced highest at 28oC with 3.10 mg/ml and A.awamoriA2 produced lowest at 26OC (2.08mg/ml). A. niger F4 produced the highest at32OC with 5.03mg/ml and A.niger F5 lowest at 26OC with 3.10mg/ml. Fermentation duration showed duration by A. awamori A2 after 144hours with 5.00mg/ml and A. awamori A1 showed lowest yield after 24hours with 0.71mg/ml while A. niger F5 yield highest after 168 hours with 5.02mg/ml and A. niger F4 yield lowest after 24hours with 0.91mg/ml. Effect of pH on citric acid production showed that A. awamoriA1 yield highest at pH 4.5 with 5.19mg/ml while A. nigerF5 produced highest at pH 5.0 with citric acid yield of 5.69mg/l.