Affiliation:
1. Institute of Fundamental Medicine and Biology, Kazan (Volga Region) Federal University, Kazan, Republic of Tatarstan, Russia
2. Department of Food Technology and Bioprocess Engineering, Max Rubner Institut, Karlsruhe, Germany
3. Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA
Abstract
ABSTRACT
Phosphorus is an important macronutrient, but its availability in soil is limited. Many soil microorganisms improve the bioavailability of phosphate by releasing it from various organic compounds, including phytate. To investigate the diversity of phytate-hydrolyzing bacteria in soil, we sampled soils of various ecological habitats, including forest, private homesteads, large agricultural complexes, and urban landscapes. Bacterial isolate
Pantoea
sp. strain 3.5.1 with the highest level of phytase activity was isolated from forest soil and investigated further. The
Pantoea
sp. 3.5.1
agpP
gene encoding a novel glucose-1-phosphatase with high phytase activity was identified, and the corresponding protein was purified to apparent homogeneity, sequenced by mass spectroscopy, and biochemically characterized. The AgpP enzyme exhibits maximum activity and stability at pH 4.5 and at 37°C. The enzyme belongs to a group of histidine acid phosphatases and has the lowest
K
m
values toward phytate, glucose-6-phosphate, and glucose-1-phosphate. Unexpectedly, stimulation of enzymatic activity by several divalent metal ions was observed for the AgpP enzyme. High-performance liquid chromatography (HPLC) and high-performance ion chromatography (HPIC) analyses of phytate hydrolysis products identify
dl
-
myo
-inositol 1,2,4,5,6-pentakisphosphate as the final product of the reaction, indicating that the
Pantoea
sp. AgpP glucose-1-phosphatase can be classified as a 3-phytase. The identification of the
Pantoea
sp. AgpP phytase and its unusual regulation by metal ions highlight the remarkable diversity of phosphorus metabolism regulation in soil bacteria. Furthermore, our data indicate that natural forest soils harbor rich reservoirs of novel phytate-hydrolyzing enzymes with unique biochemical features.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
47 articles.
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