The role of PTP-like phytases in ruminal phytate digestion

植酸盐是储存在谷物中的磷的主要形式，因此是集约化畜牧生产中使用的基于谷物的饮食中磷的主要来源。植酸磷对于非反刍动物家畜（例如，猪、家禽），并在粪便中排泄。向可耕地施用粪肥后释放的植酸磷是一个重要的污染源，并在世界上非反刍牲畜密度高的地区造成了地表沃茨的富营养化。全球非反刍动物每年排泄的磷量超过8亿kg，对生产者来说，全球每年损失超过10亿美元。非反刍动物不能使用膳食植酸盐的一种解决方案是用植酸酶修正膳食。植酸酶释放植酸磷，从而使其可用于非反刍动物。有趣的是，瘤胃中的微生物活性使反刍动物（例如，牛、羊）使用植酸磷。本研究的总体目标是确定瘤胃厌氧细菌如何降解植酸。我们已经确定了一些高植酸酶生产的厌氧细菌在瘤胃中，包括硒单胞菌和亲属在集群IX。我建议使用生物化学和分子生物学技术来研究硒单胞菌和相关厌氧菌降解植酸的遗传学和生物化学。我的研究小组最近描述了一个由这些瘤胃细菌产生的新型植酸酶家族。我们已经鉴定了6种与蛋白酪氨酸磷酸酶有远亲关系的酶，蛋白酪氨酸磷酸酶是参与调节基本细胞过程的一类重要酶。目前，我们正在确定的结构，模式的行动和分布，试图获得洞察植酸降解及其在瘤胃磷循环中的作用，这个新的植酸酶家族。这项研究将提供新的解决方案和工具，以有效地处理日益严重的污染问题。

Phytate is the principal form of phosphorus stored in grains and, as such is the major source of phosphorus in grain-based diets used in intensive livestock production. Phytate-phosphorus is indigestible to non-ruminant livestock (e.g., swine, poultry) and excreted in the feces. Release of phytate-phosphorus following application of manure to arable lands is a significant source of pollution and has contributed to eutrophication of surface waters in areas of the world with high densities of non-ruminant livestock. The annual amount of phosphorus excreted globally by non-ruminants exceeds 800,000,000 kg and represents to producers an annual worldwide loss of greater than $1 billion dollars. One solution to the inability of non-ruminants to use dietary phytate is the amendment of diets with phytases. Phytases release phytate-phosphorus, thereby making it available to non-ruminant animals. Interestingly, microbial activities in the rumen enable ruminant animals (e.g., cattle, sheep) to use phytate-phosphorus. The overall objective of my research is to determine how ruminal anaerobic bacteria degrade phytate. We have identified a number of high phytase producing anaerobic bacteria in the rumen, including Selenomonads and relatives in cluster IX. I propose to use techniques in biochemistry and molecular biology to study the genetics and biochemistry of phytate degradation by Selenomonads and related anaerobic bacteria. My research group has recently described a novel family of phytases produced by these rumen bacteria. We have characterized 6 enzymes that are distantly related to Protein Tyrosine Phosphatases, an important class of enzymes involved in regulating fundamental cellular processes. We are currently determining the structure, mode of action and distribution of this new family of phytase in an attempt to gain insights into phytate degradation and its role in phosphorus cycling in the rumen. This research will provide new solutions and tools to deal effectively with a growing pollution problem.