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Purification and biochemical characterization of ferulic acid esterase from Aspergillus niger CFR 1105

Shyamala Ganapati, Hegde (2009) Purification and biochemical characterization of ferulic acid esterase from Aspergillus niger CFR 1105. PhD thesis, University of Mysore.


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Ferulic acid esterase (FAE, EC, a biotechnologically important enzyme is responsible for the hydrolysis of the ester linkage present between 3-methoxy 4-hydroxy cinnamic acid (ferulic acid), and sugars and for their subsequent utilization as bioactive compounds. The major focus of the present work was to study ferulic acid esterase from a strain of Aspergillus niger (CFR 1105) with respect to (a) optimization of growth conditions of Aspergillus niger CFR 1105 for the enrichment of ferulic acid esterase, (b) its purification and partial characterization. A spectrophotometric substrate namely 4-nitrophenyl ferulate was synthesized by a single step dehydrative coupling of ferulic acid and 4-nitrophenol and characterized by HPLC, ESI-MS, 1H and 13C NMR for the assay of ferulic acid esterase. Ferulic acid esterase activity was detected in the culture filtrate of A. niger grown on wheat bran, whereas it was absent in the culture filtrates of Aspergillus oryzae and Rhizopus arrhizus grown on wheat bran. FAE activities produced by A. niger grown in both solid state (ssf) and submerged fermentation (smf) using wheat bran as a carbon source and also as an inducer of the enzyme were comparable, however specific activity of the enzyme in culture filtrate of smf was double than that of ssf and was constant upto 5 days and this condition was chosen for isolation and purification of ferulic acid esterase. Two isoenzymes, designated as FAE-1 and FAE-2 were isolated and purified to homogeneity by conventional protein purification methods from the 5th day culture filtrate of A. niger grown in smf with a fold purification of 11 and 25 respectively. Molecular weights of FAE-1 and FAE-2 were found to be 50 kDa and 55 kDa respectively. FAE-1 and FAE-2 are glycoproteins with carbohydrate content of 23% and 30% respectively. FAE-1 and FAE-2 exhibited pH optima of 9 and 6 respectively and both were stable over pH range of 6 to 9. FAE-1showed temperature optimum of 40 0C whereas FAE-2 showed wider temperature optimum of 40-50 0C. They showed highest specific activity towards p-nitrophenyl ferulate followed by p-nitrophenyl acetate and p-nitrophenyl butyrate. The thesis ends with summary and conclusions along with list of references.

Item Type: Thesis (PhD)
Uncontrolled Keywords: Ferulic acid esterase, Aspergillus niger
Subjects: 600 Technology > 08 Food technology > 16 Nutritive value > 05 Enzymes
500 Natural Sciences and Mathematics > 07 Life Sciences > 04 Microbiology > 04 Fungi
Divisions: Dept. of Biochemistry
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 01 Mar 2011 11:06
Last Modified: 28 Dec 2011 10:21
URI: http://ir.cftri.com/id/eprint/9956

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