TY - BOOK
T1 - New microorganisms for mobilization of organic phosphate from soil
AU - Pittroff, Sabrina Marie
PY - 2019
Y1 - 2019
N2 - A Short Introduction to a Big Problem. Agriculture and crop production are experiencing a drastic amount of pressure in order to feed a growing population. At the time of this thesis, we are 7.7 billion people on the planet, and by 2050 we are expected to be over 9 billion! Collectively, as 9 billion people, we are inevitably going to eat a lot more than current time, therefore an intensified agricultural scene will demand increased fertilizer and leave little room for failure. This generally implies consistent input of macronutrients; Nitrogen (N), Phosphorus (P), and potassium (K), and implementing innovative technologies that are well understood and have minimal risk. However, the phosphate sources we rely on for P fertilizer are a finite source, and herein lies the problem - we have created an open P cycle at a global scale. Therefore, this thesis focuses on development in the direction of improved phosphorus utilisation in agricultural soils, as a potential strategy in reducing P fertilizer application. Focus of the PhD. work: contributing to a solution. Agricultural soils contain a large amount of phosphorus that is present in forms that are not available to plants. Furthermore, fertilizer applications are often made in excess of the amount required by the crop. This has resulted in accumulation of phosphorus in some agricultural soils and soil experts estimate that many agricultural soils now contain sufficient P reserves to buffer threats to food security. Microbial life in the soil is responsible for an alarming amount of services, one of which is nutrient turn over. These remarkable microorganisms are responsible for a large part of the phosphorus cycle and are irreplaceable in their role of shuffling phosphorus from unavailable forms to forms suitable for biological use. This thesis aims to contribute knowledge to the microbial ecology that will be key in harvesting the phosphorus that is currently fixed in soil, which will be one part of solving the open phosphorus cycle problem. In one part of this thesis, we work with an existing microbial inoculant, Penicillium bilaii, in soil and plant experiments to better understand its mechanism in circulating phosphorus. In another part of this thesis we take a more novel approach which builds on the knowledge of documented alkaline phytase enzymes (beta propeller phytases) and their specific substrate; calcium phytate. This approach is unique in that we extend the theory to an in-soil microcosm baiting system, and use it to study the soil bacterial ecology of insoluble organic phosphates. PhD project scientific results. An in-soil microcosm was designed and tested, providing a novel method for soil ecologists to study communities attracted to substrates of their interest. Our employment of this microcosm utilized the precipitated calcium phosphate substrate, which allowed us to gain information surrounding bacterial communities attracted to organic phosphorus. Findings here indicated that the genus Streptomyces is likely a contributor in addressing the organic phosphorus pool in soils containing calcium-bound phytate. Isolation of select strains recovered from the microcosm provide novel strains from Arthrobacter and Bacillus genera which show the ability to mineralize precipitated phytate, as well as confirming an important role of Pseudomonas in the cycling of phytate in soil. Studies on the existing commercial inoculant, Penicillium bilaii, revealed important details surrounding its proliferation when inoculated with plant seeds in low-phosphorus soils and soils amended with high-phosphorus waste. Understanding the conditions which microbial inoculants have the best chance of success and contribution potential will be key to using them reliably in agriculture; therefore, this study revealing conditions where this fungus may be limited is an important finding.
AB - A Short Introduction to a Big Problem. Agriculture and crop production are experiencing a drastic amount of pressure in order to feed a growing population. At the time of this thesis, we are 7.7 billion people on the planet, and by 2050 we are expected to be over 9 billion! Collectively, as 9 billion people, we are inevitably going to eat a lot more than current time, therefore an intensified agricultural scene will demand increased fertilizer and leave little room for failure. This generally implies consistent input of macronutrients; Nitrogen (N), Phosphorus (P), and potassium (K), and implementing innovative technologies that are well understood and have minimal risk. However, the phosphate sources we rely on for P fertilizer are a finite source, and herein lies the problem - we have created an open P cycle at a global scale. Therefore, this thesis focuses on development in the direction of improved phosphorus utilisation in agricultural soils, as a potential strategy in reducing P fertilizer application. Focus of the PhD. work: contributing to a solution. Agricultural soils contain a large amount of phosphorus that is present in forms that are not available to plants. Furthermore, fertilizer applications are often made in excess of the amount required by the crop. This has resulted in accumulation of phosphorus in some agricultural soils and soil experts estimate that many agricultural soils now contain sufficient P reserves to buffer threats to food security. Microbial life in the soil is responsible for an alarming amount of services, one of which is nutrient turn over. These remarkable microorganisms are responsible for a large part of the phosphorus cycle and are irreplaceable in their role of shuffling phosphorus from unavailable forms to forms suitable for biological use. This thesis aims to contribute knowledge to the microbial ecology that will be key in harvesting the phosphorus that is currently fixed in soil, which will be one part of solving the open phosphorus cycle problem. In one part of this thesis, we work with an existing microbial inoculant, Penicillium bilaii, in soil and plant experiments to better understand its mechanism in circulating phosphorus. In another part of this thesis we take a more novel approach which builds on the knowledge of documented alkaline phytase enzymes (beta propeller phytases) and their specific substrate; calcium phytate. This approach is unique in that we extend the theory to an in-soil microcosm baiting system, and use it to study the soil bacterial ecology of insoluble organic phosphates. PhD project scientific results. An in-soil microcosm was designed and tested, providing a novel method for soil ecologists to study communities attracted to substrates of their interest. Our employment of this microcosm utilized the precipitated calcium phosphate substrate, which allowed us to gain information surrounding bacterial communities attracted to organic phosphorus. Findings here indicated that the genus Streptomyces is likely a contributor in addressing the organic phosphorus pool in soils containing calcium-bound phytate. Isolation of select strains recovered from the microcosm provide novel strains from Arthrobacter and Bacillus genera which show the ability to mineralize precipitated phytate, as well as confirming an important role of Pseudomonas in the cycling of phytate in soil. Studies on the existing commercial inoculant, Penicillium bilaii, revealed important details surrounding its proliferation when inoculated with plant seeds in low-phosphorus soils and soils amended with high-phosphorus waste. Understanding the conditions which microbial inoculants have the best chance of success and contribution potential will be key to using them reliably in agriculture; therefore, this study revealing conditions where this fungus may be limited is an important finding.
UR - https://rex.kb.dk/permalink/f/h35n6k/KGL01012061537
M3 - Ph.D. thesis
BT - New microorganisms for mobilization of organic phosphate from soil
PB - Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen
ER -