Methodological Aspects of Measuring Phytase Activity and Phytate Phosphorus Content in Selected Cereal Grains and Digesta and Feces of Pigs
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- 作者：Yingran Shen ; Yulong Yin ; Eduardo R. Chavez ; and Ming Z. Fan
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2005
- 出版时间：February 23, 2005
- 年：2005
- 卷：53
- 期：4
- 页码：853 - 859
- 全文大小：81K
- 年卷期：v.53,no.4(February 23, 2005)
- ISSN：1520-5118
文摘
This study was to examine the time course of sample-specific linearity of intrinsic phytase hydrolysisin major cereal grains and in ileal digesta and fecal samples and to determine the time course of themicrobial phytase-catalyzed hydrolysis of various sources of phytate for estimating phytate phosphorus(P) content. The intrinsic phytase activity in barley, corn, oat, and wheat samples was measuredover multiple time points from 0 to 120 min at 1.5 mmol·L-1 of sodium phytate at pH 5.5 and 37 
C.Time courses of hydrolysis of purified phytate and phytate associated with the cereal grain samplesand the pig digesta and fecal samples were examined with the Natuphos microbial phytase overmultiple time points from 0 to 48 h of incubation. The intrinsic phytase hydrolysis was linear (P <0.05) for up to 120 min for the barley, corn, and wheat samples, whereas in the oat sample thehydrolysis was linear (P < 0.05) for only up to 30 min of incubation. The intrinsic phytase activities(phytase unit: 
mol·kg-1 of dry matter·min-1) for the barley, corn, and wheat samples were estimatedto be 693, 86, and 1189 by linear regression analysis. Intrinsic phytase activity (412 phytase units)for the oat sample based on a 30-min incubation was considerably higher than the value (103 phytaseunits) determined from the 120-min incubation for the same oat sample. There were quadratic withplateau relationships (P < 0.05) between the hydrolytic release of inorganic P from various sourcesof phytate and the incubation time. The minimal incubation times required for the complete hydrolysisof phytate were estimated to be 4, 3, and 11 h for the purified phytate, the cereal grain samples, andthe pig digesta and feces, respectively. It was concluded that multiple time point experiments needto be conducted to determine valid intrinsic phytase activity and phytate P content in samples throughintrinsic and microbial phytase hydrolysis incubations.Keywords: Intrinsic phytase activity; phytate phosphorus; cereal grains; pigs
C.Time courses of hydrolysis of purified phytate and phytate associated with the cereal grain samplesand the pig digesta and fecal samples were examined with the Natuphos microbial phytase overmultiple time points from 0 to 48 h of incubation. The intrinsic phytase hydrolysis was linear (P <0.05) for up to 120 min for the barley, corn, and wheat samples, whereas in the oat sample thehydrolysis was linear (P < 0.05) for only up to 30 min of incubation. The intrinsic phytase activities(phytase unit: mol·kg-1 of dry matter·min-1) for the barley, corn, and wheat samples were estimatedto be 693, 86, and 1189 by linear regression analysis. Intrinsic phytase activity (412 phytase units)for the oat sample based on a 30-min incubation was considerably higher than the value (103 phytaseunits) determined from the 120-min incubation for the same oat sample. There were quadratic withplateau relationships (P < 0.05) between the hydrolytic release of inorganic P from various sourcesof phytate and the incubation time. The minimal incubation times required for the complete hydrolysisof phytate were estimated to be 4, 3, and 11 h for the purified phytate, the cereal grain samples, andthe pig digesta and feces, respectively. It was concluded that multiple time point experiments needto be conducted to determine valid intrinsic phytase activity and phytate P content in samples throughintrinsic and microbial phytase hydrolysis incubations.Keywords: Intrinsic phytase activity; phytate phosphorus; cereal grains; pigs