Browsing by Author "Kizhakedathil, M.P."

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    Calcium oxalate degrading thermophilic oxalate oxidase from newly isolated Fusarium oxysporum RBP3
    (Elsevier Ltd, 2020) Kizhakedathil, M.P.; Bose, R.; Belur, P.D.
    Four oxalate oxidase (OxO) positive fungal strains were isolated from rotting taro corms. One isolate showing highest extra cellular OxO titre was selected and was identified based on partial sequencing of 18S rRNA. The selected strain was found to be Fusarium oxysporum f. sp. cumini. Oxalate oxidase (EC 1.2.3.4) titre was increased by one factor at a time approach in shake flasks. The enzyme was then purified by isopropanol precipitation followed by chromatography using ENrich SEC650 FPLC column. OxO was found to be a heterodimer having two subunits of mass 116 and 105 kDa. Optimum pH and temperature were found to be 3.8 and 80 °C respectively. OxO exhibited stability for 4 h at temperature range of 4–95 °C and pH between 2.2 and 10.0. OxO was inactive until 30 °C and more than 90% of its peak activity was observed at temperature above 80 °C, suggesting that the enzyme is thermophilic. OxO appears to be a metalloprotein inhibited by Cu2+, Fe2+ and EDTA and enhanced in the presence of Mn2+ and biotin. OxO also exhibited broad substrate specificity. This enzyme was found to decompose insoluble calcium oxalate crystals. This is the first report of OxO decomposing calcium oxalate crystals. © 2020
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    Optimization of oxalate-free starch production from Taro flour by oxalate oxidase assisted process
    (Bellwether Publishing, Ltd., 2021) Kizhakedathil, M.P.; Suvarna, S.; Belur, P.D.; Wongsagonsup, R.; Agoo, E.M.G.; Janairo, J.I.B.
    Taro (Colocasia esculenta) starch is known to possess unique physical and functional properties such as low amylose content, A-crystalline form, small granules, higher swelling power, etc. Due to the presence of significant amount of calcium oxalate crystals, the food industry is reluctant to explore this unique and cheap starch source for various food applications. Traditional processes utilizing various physical and chemical methods to remove oxalate content of starch inevitably change its physical and functional properties. However, using oxalate oxidase can effectively remove oxalates without altering the unique properties of starch. Hence, an attempt was made to optimize oxalate oxidase assisted starch extraction process from taro flour using response surface methodology. A central composite design comprising 20 experimental trials with 10 cube points augmented with six axial points and four replicates at the center point was applied. A mathematical model was developed to show the effect of taro flour concentration, enzyme load and incubation time on the oxalate removal. Validity of the model was experimentally verified and found that 98.3% of total oxalates can be removed under optimal conditions. This is the first report of optimization of the production of starch from taro flour using microbial oxalate oxidase. © 2020 Taylor & Francis Group, LLC.