Veide Jenny, Andlid Thomas
Chalmers University of Technology, Department of Chemical and Biological Engineering/Food Science, Box 5401, SE-402 29 Göteborg, Sweden.
Int J Food Microbiol. 2006 Apr 15;108(1):60-7. doi: 10.1016/j.ijfoodmicro.2005.10.020. Epub 2006 Feb 14.
Myo-inositol hexaphosphate (IP6, phytate) is a potent anti-nutritional compound occurring in many plant-based staple foods, limiting the bioavailability of important nutrients such as iron and zinc. The objective of the present study was to investigate different strategies to achieve high and constitutive extracellular IP6 degradation by Baker's yeast, Saccharomyces cerevisiae. By deleting either of the genes PHO80 and PHO85, encoding negative regulators of the transcription of the repressible acid phosphatases (rAPs), the IP6 degradation became constitutive, and the biomass specific IP6 degradation was increased manyfold. In addition, the genes encoding the transcriptional activator Pho4p and the major rAP Pho5p were overexpressed in both a wild-type and a pho80delta strain, yielding an additional increase in IP6 degradation. It has previously been proved possible to increase human iron bioavailability by degradation of IP6 using microbial phytase. A high-phytase S. cerevisiae strain, without the use of any heterologous DNA, may be a suitable organism for the production of food-grade phytase and for the direct use in food production.
肌醇六磷酸（IP6，植酸）是一种存在于许多植物性主食中的强效抗营养化合物，会限制铁和锌等重要营养素的生物利用度。本研究的目的是探究不同策略，以使酿酒酵母（Saccharomyces cerevisiae）实现高水平且组成型的细胞外IP6降解。通过缺失编码可阻遏酸性磷酸酶（rAPs）转录负调控因子的PHO80和PHO85基因中的任意一个，IP6降解变为组成型，且生物量特异性IP6降解增加了许多倍。此外，编码转录激活因子Pho4p和主要rAP Pho5p的基因在野生型和pho80delta菌株中均过表达，使得IP6降解进一步增加。此前已证明，使用微生物植酸酶降解IP6可提高人体对铁的生物利用度。一种不使用任何异源DNA的高植酸酶酿酒酵母菌株，可能是生产食品级植酸酶以及直接用于食品生产的合适生物体。
