Valorizing olive oil by-products as sustainable biological nitrification inhibitors: phenolic profiling, in vitro activity against Nitrosomonas europaea, and biodegradability assessment

Abstract Background The valorization of agro-industrial by-products is a key strategy for promoting sustainable agriculture and minimizing environmental impacts. Olive mill wastewater (OMW) and olive leaves (OL) contain high concentrations of phenolic compounds, which have shown potential as biologi...

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Main Authors: Adrián Hernández Fernández, Eduardo Iniesta Lopez, Yolanda Garrido, Ana Sánchez Zurano, Antonia Pérez de los Ríos, Francisco José Hernández Fernández
Format: Article
Language:English
Published: SpringerOpen 2025-06-01
Series:Chemical and Biological Technologies in Agriculture
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Online Access:https://doi.org/10.1186/s40538-025-00796-w
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author Adrián Hernández Fernández
Eduardo Iniesta Lopez
Yolanda Garrido
Ana Sánchez Zurano
Antonia Pérez de los Ríos
Francisco José Hernández Fernández
author_facet Adrián Hernández Fernández
Eduardo Iniesta Lopez
Yolanda Garrido
Ana Sánchez Zurano
Antonia Pérez de los Ríos
Francisco José Hernández Fernández
author_sort Adrián Hernández Fernández
collection DOAJ
description Abstract Background The valorization of agro-industrial by-products is a key strategy for promoting sustainable agriculture and minimizing environmental impacts. Olive mill wastewater (OMW) and olive leaves (OL) contain high concentrations of phenolic compounds, which have shown potential as biological nitrification inhibitors (BNIs), offering a sustainable alternative to reduce nitrogen pollution in agroecosystems. This study aims to characterize the phenolic profile of these by-products, assess their antioxidant properties, evaluate their inhibitory effects on nitrification, and determine their biodegradability. Results Hydroxytyrosol (1.521 g L⁻1) was identified as the dominant phenolic compound in OMW, while oleuropein (1.824 g L⁻1) prevailed in OL extracts. Both solutions exhibited moderate to high antioxidant activity, with DPPH EC50 values of 1.84 and 2.06 mg L⁻1 for OL and OMW, respectively. Nitrification inhibition assays using Nitrosomonas europaea showed IC50 values of 0.2806 g L⁻1 for OMW and 0.1735 g L⁻1 for OL. Biodegradability tests indicated degradation rates of 52–53% for OMW and 54–55% for OL at 350 and 700 mg L⁻1 COD. Elemental analysis confirmed the presence of essential macronutrients (K, P, Ca, Mg) and micronutrients (Fe, Zn, Mn, Cu, Ni) in both solutions, supporting soil fertility while maintaining low heavy metal concentrations. Conclusions These findings highlight the dual benefits of OMW and OL solutions: reducing nitrogen losses through nitrification inhibition while contributing to soil health and circular economy models. Although their biodegradability does not strictly meet OECD criteria for readily biodegradable compounds, optimizing microbial communities could enhance their degradation. The application of these biological nitrification inhibitors presents a promising alternative to synthetic nitrification inhibitors, fostering eco-friendly agricultural practices. Graphical Abstract
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spelling doaj-art-b778718320114e3091f2acca143603d52025-08-20T03:21:02ZengSpringerOpenChemical and Biological Technologies in Agriculture2196-56412025-06-0112111510.1186/s40538-025-00796-wValorizing olive oil by-products as sustainable biological nitrification inhibitors: phenolic profiling, in vitro activity against Nitrosomonas europaea, and biodegradability assessmentAdrián Hernández Fernández0Eduardo Iniesta Lopez1Yolanda Garrido2Ana Sánchez Zurano3Antonia Pérez de los Ríos4Francisco José Hernández Fernández5Department of Chemical Engineering, University of MurciaDepartment of Chemical Engineering, University of MurciaDepartment of Chemical Engineering, University of MurciaDepartment of Chemical Engineering, University of MurciaDepartment of Chemical Engineering, University of MurciaDepartment of Chemical Engineering, University of MurciaAbstract Background The valorization of agro-industrial by-products is a key strategy for promoting sustainable agriculture and minimizing environmental impacts. Olive mill wastewater (OMW) and olive leaves (OL) contain high concentrations of phenolic compounds, which have shown potential as biological nitrification inhibitors (BNIs), offering a sustainable alternative to reduce nitrogen pollution in agroecosystems. This study aims to characterize the phenolic profile of these by-products, assess their antioxidant properties, evaluate their inhibitory effects on nitrification, and determine their biodegradability. Results Hydroxytyrosol (1.521 g L⁻1) was identified as the dominant phenolic compound in OMW, while oleuropein (1.824 g L⁻1) prevailed in OL extracts. Both solutions exhibited moderate to high antioxidant activity, with DPPH EC50 values of 1.84 and 2.06 mg L⁻1 for OL and OMW, respectively. Nitrification inhibition assays using Nitrosomonas europaea showed IC50 values of 0.2806 g L⁻1 for OMW and 0.1735 g L⁻1 for OL. Biodegradability tests indicated degradation rates of 52–53% for OMW and 54–55% for OL at 350 and 700 mg L⁻1 COD. Elemental analysis confirmed the presence of essential macronutrients (K, P, Ca, Mg) and micronutrients (Fe, Zn, Mn, Cu, Ni) in both solutions, supporting soil fertility while maintaining low heavy metal concentrations. Conclusions These findings highlight the dual benefits of OMW and OL solutions: reducing nitrogen losses through nitrification inhibition while contributing to soil health and circular economy models. Although their biodegradability does not strictly meet OECD criteria for readily biodegradable compounds, optimizing microbial communities could enhance their degradation. The application of these biological nitrification inhibitors presents a promising alternative to synthetic nitrification inhibitors, fostering eco-friendly agricultural practices. Graphical Abstracthttps://doi.org/10.1186/s40538-025-00796-wNatural nitrification inhibitorsOlive mill wastewaterOlive leavesPhenolic compoundsNitrosomonas europaea
spellingShingle Adrián Hernández Fernández
Eduardo Iniesta Lopez
Yolanda Garrido
Ana Sánchez Zurano
Antonia Pérez de los Ríos
Francisco José Hernández Fernández
Valorizing olive oil by-products as sustainable biological nitrification inhibitors: phenolic profiling, in vitro activity against Nitrosomonas europaea, and biodegradability assessment
Chemical and Biological Technologies in Agriculture
Natural nitrification inhibitors
Olive mill wastewater
Olive leaves
Phenolic compounds
Nitrosomonas europaea
title Valorizing olive oil by-products as sustainable biological nitrification inhibitors: phenolic profiling, in vitro activity against Nitrosomonas europaea, and biodegradability assessment
title_full Valorizing olive oil by-products as sustainable biological nitrification inhibitors: phenolic profiling, in vitro activity against Nitrosomonas europaea, and biodegradability assessment
title_fullStr Valorizing olive oil by-products as sustainable biological nitrification inhibitors: phenolic profiling, in vitro activity against Nitrosomonas europaea, and biodegradability assessment
title_full_unstemmed Valorizing olive oil by-products as sustainable biological nitrification inhibitors: phenolic profiling, in vitro activity against Nitrosomonas europaea, and biodegradability assessment
title_short Valorizing olive oil by-products as sustainable biological nitrification inhibitors: phenolic profiling, in vitro activity against Nitrosomonas europaea, and biodegradability assessment
title_sort valorizing olive oil by products as sustainable biological nitrification inhibitors phenolic profiling in vitro activity against nitrosomonas europaea and biodegradability assessment
topic Natural nitrification inhibitors
Olive mill wastewater
Olive leaves
Phenolic compounds
Nitrosomonas europaea
url https://doi.org/10.1186/s40538-025-00796-w
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