Schlemmer U, Jany K D, Berk A, Schulz E, Rechkemmer G
Federal Research Centre for Nutrition, Institute of Nutritional Physiology, Karlsruhe, Germany.
Arch Tierernahr. 2001;55(4):255-80. doi: 10.1080/17450390109386197.
The present study gives an overview on the whole mechanism of phytate degradation in the gut and the enzymes involved. Based on the similarity of the human and pigs gut, the study was carried out in pigs as model for humans. To differentiate between intrinsic feed phytases and endogenous phytases hydrolysing phytate in the gut, two diets, one high (control diet) and the other one very low in intrinsic feed phytases (phytase inactivated diet) were applied. In the chyme of stomach, small intestine and colon inositol phosphate isomers and activities of phytases and alkaline phosphatases were determined. In parallel total tract phytate degradation and apparent phosphorus digestibility were assessed. In the stomach chyme of pigs fed the control diet, comparable high phytase activity and strong phytate degradation were observed. The predominant phytate hydrolysis products were inositol phosphates, typically formed by plant phytases. For the phytase inactivated diet, comparable very low phytase activity and almost no phytate degradation in the stomach were determined. In the small intestine and colon, high activity of alkaline phosphatases and low activity of phytases were observed, irrespective of the diet fed. In the colon, stronger phytate degradation for the phytase inactivated diet than for the control diet was detected. Phytate degradation throughout the whole gut was nearly complete and very similar for both diets while the apparent availability of total phosphorus was significantly higher for the pigs fed the control diet than the phytase inactivated diet. The pathway of inositol phosphate hydrolysis in the gut has been elucidated.
本研究概述了肠道中植酸盐降解的整体机制及相关酶。基于人类和猪肠道的相似性，以猪作为人类模型开展了该研究。为区分饲料中的固有植酸酶和肠道中水解植酸盐的内源性植酸酶，采用了两种日粮，一种固有饲料植酸酶含量高（对照日粮），另一种固有饲料植酸酶含量极低（植酸酶失活日粮）。测定了胃、小肠和结肠食糜中肌醇磷酸异构体以及植酸酶和碱性磷酸酶的活性。同时评估了全肠道植酸盐降解和表观磷消化率。在饲喂对照日粮的猪的胃食糜中，观察到相当高的植酸酶活性和强烈的植酸盐降解。主要的植酸盐水解产物是肌醇磷酸，通常由植物植酸酶形成。对于植酸酶失活日粮，测定出胃中的植酸酶活性相当低，且几乎没有植酸盐降解。在小肠和结肠中，无论饲喂何种日粮，均观察到碱性磷酸酶活性高而植酸酶活性低。在结肠中，检测到植酸酶失活日粮的植酸盐降解比对照日粮更强。两种日粮在整个肠道中的植酸盐降解几乎都很完全且非常相似，而饲喂对照日粮的猪的总磷表观利用率显著高于饲喂植酸酶失活日粮的猪。肠道中肌醇磷酸的水解途径已得到阐明。
