Biochemical Characterization of Crude α-Amylase of Aspergillus spp. Associated with the Spoilage of Cassava (Manihot esculenta) Tubers and Processed Products in Nigeria
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Date
2015-02
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Advances in Biochemistry
Abstract
In this research, crude α-amylases associated with the spoilage of cassava (Manihot esculenta) tubers/ product
(‘eba’) were biochemically characterized. They were isolated from five fungi: Aspergillus sp. CSA25, Aspergillus sp. CSA26, Aspergillus sp. CSA27, Aspergillus sp. CSA35 and Aspergillus sp. CSA38. The results of the analyses showed that the activities of α-amylase obtained from both sources (cassava tuber/ eba) were optimal at 45°C and pH 5.0. The maximum specific activity (Vmax) of the enzyme was found to be 10 U/mg protein, while its Michaelis-Menten constant (Km) was between 0.37 -1.25%w/v. The α-amylase is thermally stable for 1 - 2 h at optimum temperature and pH (45°C; pH 5.0). A broad range of substrate specificity was expressed by the enzyme for cassava starch-containing products (tapioca flour, garri flour, cassava flour, 1%, w/v); however, potato (Ipomoea batatas) starch, yam (Dioscorea rotundata) flour and cocoyam (Colocasia esculenta) flour were relatively minimally hydrolyzed by the crude α-amylases obtained from Aspergillus spp. that
caused spoilage of cassava. Ethylenediamine tetraacetic acid (1 mM EDTA) and Mg2+ treatment had no significant (p > 0.05) effect on the activities of the amylase, but Na+, K+, Ca2+, Fe3+, thiourea and 5′,5′-dithiobis-2-nitrobenzoate (1 mM DTNB) enhanced its activities. The fungal α-amylases were most activated by K+ and had a salt tolerance of 1 - 2 M NaCl for 24 h. The fungal α-amylases reported in this study would find useful application in industries like food industry, detergent industry, paper industry, textile industry, pharmaceutical industry, etc where microbial α-amylases would be required for efficient and
cost-effective hydrolysis of cassava starch, cassava flour and or its products.
Description
doi: 10.11648/j.ab.20150301.14
Keywords
Manihot esculenta (Cassava), Aspergillus spp., α-Amylase, Biochemical Characterization
Citation
Oghenetega Jonathan Avwioroko, Nyerhovwo John Tonukari, Samuel Ogheneovo Asagba. Biochemical Characterization of Crude αAmylase of Aspergillus spp. Associated with the Spoilage of Cassava (Manihot esculenta) Tubers and Processed Products in Nigeria. Advances in Biochemistry. Vol. 3, No. 1, 2015, pp. 15-23. doi: 10.11648/j.ab.20150301.14