Combined Effects of Biochar and Rhamnolipid on Phenanthrene Biodegradation in Agricultural Soil: Bioavailability and Microbial Community Dynamics

The present study investigated the combined effects of wheat straw biochar (BC) and biosurfactant rhamnolipid (RL) on the biodegradation kinetics of phenanthrene by indigenous microorganisms in agricultural soil, focusing on dynamic responses of both bioavailability and community structure. The comb...

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Main Authors: Meng Zhang, Yuke Kang, Jie Ran, Jichao Song, Zhongyi Wang, Jiawang Li, Liyuan Chen
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Agriculture
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Online Access:https://www.mdpi.com/2077-0472/15/11/1116
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author Meng Zhang
Yuke Kang
Jie Ran
Jichao Song
Zhongyi Wang
Jiawang Li
Liyuan Chen
author_facet Meng Zhang
Yuke Kang
Jie Ran
Jichao Song
Zhongyi Wang
Jiawang Li
Liyuan Chen
author_sort Meng Zhang
collection DOAJ
description The present study investigated the combined effects of wheat straw biochar (BC) and biosurfactant rhamnolipid (RL) on the biodegradation kinetics of phenanthrene by indigenous microorganisms in agricultural soil, focusing on dynamic responses of both bioavailability and community structure. The combined treatment (BC + RL, 60.63%) significantly enhanced phenanthrene biodegradation compared to RL alone (54.74%) and the control (45.98%), while BC amendment alone (42.55%) notably inhibited biodegradation by reducing phenanthrene bioavailability despite increasing bacterial abundance, enzyme activity, and community diversity. Both RL and BC + RL treatments promoted bioavailability by transforming phenanthrene from tightly bound (very slowly desorbing fraction, <i>F</i><sub>vslow</sub>) to readily bioavailable fractions (rapidly and slowly desorbing fractions, <i>F</i><sub>rapid</sub> and <i>F</i><sub>slow</sub>), as revealed by sequential Tenax extraction. The RL-mediated increase in phenanthrene bioavailability to microbes by 11.93–17.90% via solubilization greatly enriched PAH-degrading bacterial genera and the <i>nid</i>A gene, contributing to enhanced biodegradation. The BC + RL combination outperformed the single application of RL in improving phenanthrene biodegradation due to their synergy in stimulating microbial population and activity (e.g., <i>Bacillus</i>, <i>Massilia</i>, <i>Sphingomonas</i>, and polyphenol oxidase) as a growth stimulus. These findings demonstrate that BC and RL co-application enhances PAH removal through improved bioavailability and optimized microbial communities, offering a promising strategy for soil bioremediation to ensure agricultural product safety.
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issn 2077-0472
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spelling doaj-art-72ced28459cc4f5f9a628a93b10357592025-08-20T03:10:50ZengMDPI AGAgriculture2077-04722025-05-011511111610.3390/agriculture15111116Combined Effects of Biochar and Rhamnolipid on Phenanthrene Biodegradation in Agricultural Soil: Bioavailability and Microbial Community DynamicsMeng Zhang0Yuke Kang1Jie Ran2Jichao Song3Zhongyi Wang4Jiawang Li5Liyuan Chen6Co-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, ChinaCo-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, ChinaCo-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, ChinaCo-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, ChinaCo-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, ChinaCo-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, ChinaCo-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, ChinaThe present study investigated the combined effects of wheat straw biochar (BC) and biosurfactant rhamnolipid (RL) on the biodegradation kinetics of phenanthrene by indigenous microorganisms in agricultural soil, focusing on dynamic responses of both bioavailability and community structure. The combined treatment (BC + RL, 60.63%) significantly enhanced phenanthrene biodegradation compared to RL alone (54.74%) and the control (45.98%), while BC amendment alone (42.55%) notably inhibited biodegradation by reducing phenanthrene bioavailability despite increasing bacterial abundance, enzyme activity, and community diversity. Both RL and BC + RL treatments promoted bioavailability by transforming phenanthrene from tightly bound (very slowly desorbing fraction, <i>F</i><sub>vslow</sub>) to readily bioavailable fractions (rapidly and slowly desorbing fractions, <i>F</i><sub>rapid</sub> and <i>F</i><sub>slow</sub>), as revealed by sequential Tenax extraction. The RL-mediated increase in phenanthrene bioavailability to microbes by 11.93–17.90% via solubilization greatly enriched PAH-degrading bacterial genera and the <i>nid</i>A gene, contributing to enhanced biodegradation. The BC + RL combination outperformed the single application of RL in improving phenanthrene biodegradation due to their synergy in stimulating microbial population and activity (e.g., <i>Bacillus</i>, <i>Massilia</i>, <i>Sphingomonas</i>, and polyphenol oxidase) as a growth stimulus. These findings demonstrate that BC and RL co-application enhances PAH removal through improved bioavailability and optimized microbial communities, offering a promising strategy for soil bioremediation to ensure agricultural product safety.https://www.mdpi.com/2077-0472/15/11/1116biocharrhamnolipidPAHsbiodegradationbioavailabilitymicrobial community
spellingShingle Meng Zhang
Yuke Kang
Jie Ran
Jichao Song
Zhongyi Wang
Jiawang Li
Liyuan Chen
Combined Effects of Biochar and Rhamnolipid on Phenanthrene Biodegradation in Agricultural Soil: Bioavailability and Microbial Community Dynamics
Agriculture
biochar
rhamnolipid
PAHs
biodegradation
bioavailability
microbial community
title Combined Effects of Biochar and Rhamnolipid on Phenanthrene Biodegradation in Agricultural Soil: Bioavailability and Microbial Community Dynamics
title_full Combined Effects of Biochar and Rhamnolipid on Phenanthrene Biodegradation in Agricultural Soil: Bioavailability and Microbial Community Dynamics
title_fullStr Combined Effects of Biochar and Rhamnolipid on Phenanthrene Biodegradation in Agricultural Soil: Bioavailability and Microbial Community Dynamics
title_full_unstemmed Combined Effects of Biochar and Rhamnolipid on Phenanthrene Biodegradation in Agricultural Soil: Bioavailability and Microbial Community Dynamics
title_short Combined Effects of Biochar and Rhamnolipid on Phenanthrene Biodegradation in Agricultural Soil: Bioavailability and Microbial Community Dynamics
title_sort combined effects of biochar and rhamnolipid on phenanthrene biodegradation in agricultural soil bioavailability and microbial community dynamics
topic biochar
rhamnolipid
PAHs
biodegradation
bioavailability
microbial community
url https://www.mdpi.com/2077-0472/15/11/1116
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