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From biomass to bioeconomy: engineering biocatalytic phosphorus mobilization from plant residues prior to animal feeding
Citation Link: https://doi.org/10.15480/882.15088
Publikationstyp
Doctoral Thesis
Date Issued
2025
Sprache
English
Author(s)
Advisor
Referee
Title Granting Institution
Technische Universität Hamburg
Place of Title Granting Institution
Hamburg
Examination Date
2025-03-27
Institute
TORE-DOI
Citation
Technische Universität Hamburg (2025)
In this work, the technical applicability of biocatalytic phosphorus (P)-mobilization from plant residues and the subsequent conversion of mobilized P into fertilizer has been investigated. Initially, P organically bound to phytate, is liberated by intrinsic and exogenous phytase enzymes. By conditioning plant residues prior to feeding, the enzymatic P-mobilization aims to generate high value feed material and promote a sustainable P-management. Rye bran, a by-product of the milling industry known for its high phytate content, is used as a model substrate in this research.
To monitor and evaluate the P-mobilization rate, an inline process analysis based on Fourier-Transform-Infrared spectroscopy was established. The developed inline analytical approach experienced a root mean squared error of prediction of 81 mgP∙100gbran-1, corresponding to a deviation of about 8% with respect to the total phytate content in rye bran. Using this approach, it is shown that metabolically induced germination activates intrinsic phytate hydrolyzing enzymes. Maximum intrinsic activity was identified at 43 °C, pH 5.3, and a bran to water ratio of 1 to 7 (w/v). Under these conditions, most of the phytate present was degraded within 30 min at a rate of 5565 U∙kgbran-1. For maximum P-mobilization, an exogenously applied phytase blend consisting of rPhyXT52 phytase and the phytase from D. castelli was used. Kinetic studies on the phytase blend demonstrated its suitability for batch operation. The P-mobilization process achieved complete elimination of phytate, resulting in a 90% reduction of the total P-content across different scales up to 400 L reactions. Supportive ultrasound as well as enzymatic treatment of the cellular matrix substantially increased the P-mobilization rate by over 90%. Among the enzyme formulations tested, xylanases showed the most pronounced effect. Struvite precipitation from the process wastewater containing the mobilized P achieved 99% P-recovery with over 90% purity at pH 9, 20 °C, and an equimolar input ratio of constitution ions. The results and observations indicate a very robust process and underline the feasibility and applicability of enzymatic P-mobilization and struvite precipitation for P-recovery on a larger scale. The production of value-added feed material through phytate depletion and utilization of phytate bound P in renewable resources contributes to a more resilient P-bioeconomy.
To monitor and evaluate the P-mobilization rate, an inline process analysis based on Fourier-Transform-Infrared spectroscopy was established. The developed inline analytical approach experienced a root mean squared error of prediction of 81 mgP∙100gbran-1, corresponding to a deviation of about 8% with respect to the total phytate content in rye bran. Using this approach, it is shown that metabolically induced germination activates intrinsic phytate hydrolyzing enzymes. Maximum intrinsic activity was identified at 43 °C, pH 5.3, and a bran to water ratio of 1 to 7 (w/v). Under these conditions, most of the phytate present was degraded within 30 min at a rate of 5565 U∙kgbran-1. For maximum P-mobilization, an exogenously applied phytase blend consisting of rPhyXT52 phytase and the phytase from D. castelli was used. Kinetic studies on the phytase blend demonstrated its suitability for batch operation. The P-mobilization process achieved complete elimination of phytate, resulting in a 90% reduction of the total P-content across different scales up to 400 L reactions. Supportive ultrasound as well as enzymatic treatment of the cellular matrix substantially increased the P-mobilization rate by over 90%. Among the enzyme formulations tested, xylanases showed the most pronounced effect. Struvite precipitation from the process wastewater containing the mobilized P achieved 99% P-recovery with over 90% purity at pH 9, 20 °C, and an equimolar input ratio of constitution ions. The results and observations indicate a very robust process and underline the feasibility and applicability of enzymatic P-mobilization and struvite precipitation for P-recovery on a larger scale. The production of value-added feed material through phytate depletion and utilization of phytate bound P in renewable resources contributes to a more resilient P-bioeconomy.
Subjects
Phosphorus mobilization | phytate | plant residues | phosphorus reduced animal feed | phosphorus recovery | struvite | Phosphormobilisierung | Phytat | Pflanzenrückstände | phosphorreduziertes Tierfutter | Phosphorrückgewinnung | Struvit
DDC Class
630: Agriculture and Related Technologies
660: Chemistry; Chemical Engineering
628.5: Environmental Chemistry
Funding Organisations
More Funding Information
Project No. AZ 34976/01
Publication version
publishedVersion
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Name
Dissertation_NiklasWidderich.pdf
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6.63 MB
Format
Adobe PDF