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Effects of pH and temperature on amylase and glucosidase activity of exogenous enzymes.

F. X. Amaro



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Effects of pH and temperature on amylase and glucosidase activity of exogenous enzymes.
F. X. Amaro*, H. Warman, K. G. Arriola, A. T. Adesogan, D. Vyas. University of Florida Gainesville, FL.

The objective was to evaluate the effects of different pH and temperature levels on amylase and glucosidase activity of 10 exogenous enzyme preparations (E1-E3; α-amylase, E4-E7; glucoamylase, E8-E9; mix of α-amylase, glucoamylase and fungal protease, E10; α-glucosidase). Two independent 10 � 4 factorial experiments were carried out to evaluate the activities of enzymes at different pH (4, 5, 6 and 7; Exp. 1) or temperature levels (20, 30, 40 and 50�C; Exp. 2). Potato starch (1% wt/vol) was used as substrate and glucose was used as standard. For amylase activity, enzymes (diluted in citrate-phosphate buffer) were incubated in triplicate with 1 mL of substrate in a temperature-controlled water bath for 5 min, reaction was terminated by adding 3, 5-dinitrosalicylic acid, sample absorbance was read at 540 nm. For glucosidase activity, enzymes were incubated under similar conditions for 45 min; however, reaction was terminated by adding glucose oxidase and absorbance was measured at 500 nm. Glucose release (�mol /mL enzyme/min) was calculated for both amylase and glucosidase activity. Data were log normalized and GLIMMIX procedure of SAS was used to test for main effects of enzyme, pH (Exp. 1) or temperature (Exp. 2) and their interaction. In Exp. 1, an interaction effect (enzyme � pH; P < 0.05) was observed for amylase activity with maximum activity for E3 observed at pH 6.0 while pH 4.0 induced lowest activity for E10. For glucosidase activity E1, E2 and E10 showed no activity at pH levels tested; however, E4 had greatest activity at pH 5.0. In Exp. 2, an interaction between enzymes and temperature levels was observed (P < 0.01). Enzyme E3 had maximum amylase activity at 50�C while E10 had lowest activity at 20�C. Similarly, for glucosidase activity, interaction was observed for enzyme and temperature levels as E1, E2 and E10 had no activity while E7 showed maximum activity at 50�C. In conclusion, the present study confirms pH and temperature effects on amylase and glucosidase activity of exogenous enzymes. Hence, it is recommended to determine optimum pH and temperature of exogenous enzymes before inclusion in livestock diets.

Keywords: amylase, glucosidase.

Biography: Felipe Xavier Amaro originally from Brazil, got his bachelor's degree in Animal Sciences from the Universidade Federal de Vicosa in 2016. He joined the student body of the University of Florida in 2017 and got his master's degree in 2018, since then he has been working on his Ph.D. researching nutritional strategies to improve feed efficiency in dairy cattle.