Research Article | | Peer-Reviewed

Kinetics and Microbial Population Dynamics of Leaf-Biostimulated Crude Oil Bioremediation in Contrasting Soils

Received: 4 September 2026     Accepted: 16 September 2026     Published: 29 September 2026
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Abstract

Crude oil contamination remains a persistent environmental burden in petroleum-producing regions, and low-cost, locally sourced plant-leaf biostimulants offer a promising route to accelerate hydrocarbon-degrading microbial activity in impacted soils. This study evaluated the bacterial and fungal population dynamics accompanying biostimulated bioremediation of crude-oil-contaminated sandy, loamy, and clay soils amended with room-dried or sun-dried Dacryodes edulis, Canarium schweinfurthii, and Persea americana leaves at 50 g or 100 g doses, monitored over 42 days across 36 treatment bioreactors and three unamended controls. First- and second-order kinetic models were fitted to total petroleum hydrocarbon (TPH) depletion data, and total heterotrophic bacterial (THB) and fungal (THF) counts were enumerated in parallel. First-order kinetics best described the majority of treatments (R2 generally > 0.98), with rate constants of 0.035–0.067 day⁻¹ and half-lives of 10.3–19.8 days. Soil type was the dominant determinant of TPH removal (ANOVA, F = 612.5, p < 0.001), with mean removal following sandy (93.2%) > loamy (88.6%) > clay (75.5%) soil, while biostimulant species, drying method, and dose showed no statistically significant effect. All biostimulated treatments substantially outperformed unamended controls (2.4- to 2.7-fold higher removal). THB counts peaked around Day 28 before declining, and this bacterial fold-increase correlated significantly with TPH removal (r = 0.49, p = 0.0026), whereas fungal population growth did not (r = 0.01, p = 0.96). These findings indicate that soil texture, more than biostimulant identity, governs degradation outcome, and that bacterial rather than fungal proliferation drives hydrocarbon removal under these leaf-based biostimulation regimes.

Published in Science Discovery Environment (Volume 1, Issue 3)
DOI 10.11648/j.sdenv.20260103.12
Page(s) 151-165
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2026. Published by Science Publishing Group

Keywords

Bioremediation, Biostimulation, Crude Oil Degradation, Soil Texture, Hydrocarbon-utilizing Bacteria

References
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Cite This Article
  • APA Style

    Nyong, T. E., Peter, U. C. (2026). Kinetics and Microbial Population Dynamics of Leaf-Biostimulated Crude Oil Bioremediation in Contrasting Soils. Science Discovery Environment, 1(3), 151-165. https://doi.org/10.11648/j.sdenv.20260103.12

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    ACS Style

    Nyong, T. E.; Peter, U. C. Kinetics and Microbial Population Dynamics of Leaf-Biostimulated Crude Oil Bioremediation in Contrasting Soils. Sci. Discov. Environ. 2026, 1(3), 151-165. doi: 10.11648/j.sdenv.20260103.12

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    AMA Style

    Nyong TE, Peter UC. Kinetics and Microbial Population Dynamics of Leaf-Biostimulated Crude Oil Bioremediation in Contrasting Soils. Sci Discov Environ. 2026;1(3):151-165. doi: 10.11648/j.sdenv.20260103.12

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  • @article{10.11648/j.sdenv.20260103.12,
      author = {Tuboalabo Eno Nyong and Ukpaka Chukwuemeka Peter},
      title = {Kinetics and Microbial Population Dynamics of 
    Leaf-Biostimulated Crude Oil Bioremediation in Contrasting Soils},
      journal = {Science Discovery Environment},
      volume = {1},
      number = {3},
      pages = {151-165},
      doi = {10.11648/j.sdenv.20260103.12},
      url = {https://doi.org/10.11648/j.sdenv.20260103.12},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.sdenv.20260103.12},
      abstract = {Crude oil contamination remains a persistent environmental burden in petroleum-producing regions, and low-cost, locally sourced plant-leaf biostimulants offer a promising route to accelerate hydrocarbon-degrading microbial activity in impacted soils. This study evaluated the bacterial and fungal population dynamics accompanying biostimulated bioremediation of crude-oil-contaminated sandy, loamy, and clay soils amended with room-dried or sun-dried Dacryodes edulis, Canarium schweinfurthii, and Persea americana leaves at 50 g or 100 g doses, monitored over 42 days across 36 treatment bioreactors and three unamended controls. First- and second-order kinetic models were fitted to total petroleum hydrocarbon (TPH) depletion data, and total heterotrophic bacterial (THB) and fungal (THF) counts were enumerated in parallel. First-order kinetics best described the majority of treatments (R2 generally > 0.98), with rate constants of 0.035–0.067 day⁻¹ and half-lives of 10.3–19.8 days. Soil type was the dominant determinant of TPH removal (ANOVA, F = 612.5, p  loamy (88.6%) > clay (75.5%) soil, while biostimulant species, drying method, and dose showed no statistically significant effect. All biostimulated treatments substantially outperformed unamended controls (2.4- to 2.7-fold higher removal). THB counts peaked around Day 28 before declining, and this bacterial fold-increase correlated significantly with TPH removal (r = 0.49, p = 0.0026), whereas fungal population growth did not (r = 0.01, p = 0.96). These findings indicate that soil texture, more than biostimulant identity, governs degradation outcome, and that bacterial rather than fungal proliferation drives hydrocarbon removal under these leaf-based biostimulation regimes.},
     year = {2026}
    }
    

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  • TY  - JOUR
    T1  - Kinetics and Microbial Population Dynamics of 
    Leaf-Biostimulated Crude Oil Bioremediation in Contrasting Soils
    AU  - Tuboalabo Eno Nyong
    AU  - Ukpaka Chukwuemeka Peter
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    DO  - 10.11648/j.sdenv.20260103.12
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    JF  - Science Discovery Environment
    JO  - Science Discovery Environment
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    PB  - Science Publishing Group
    SN  - 3071-5431
    UR  - https://doi.org/10.11648/j.sdenv.20260103.12
    AB  - Crude oil contamination remains a persistent environmental burden in petroleum-producing regions, and low-cost, locally sourced plant-leaf biostimulants offer a promising route to accelerate hydrocarbon-degrading microbial activity in impacted soils. This study evaluated the bacterial and fungal population dynamics accompanying biostimulated bioremediation of crude-oil-contaminated sandy, loamy, and clay soils amended with room-dried or sun-dried Dacryodes edulis, Canarium schweinfurthii, and Persea americana leaves at 50 g or 100 g doses, monitored over 42 days across 36 treatment bioreactors and three unamended controls. First- and second-order kinetic models were fitted to total petroleum hydrocarbon (TPH) depletion data, and total heterotrophic bacterial (THB) and fungal (THF) counts were enumerated in parallel. First-order kinetics best described the majority of treatments (R2 generally > 0.98), with rate constants of 0.035–0.067 day⁻¹ and half-lives of 10.3–19.8 days. Soil type was the dominant determinant of TPH removal (ANOVA, F = 612.5, p  loamy (88.6%) > clay (75.5%) soil, while biostimulant species, drying method, and dose showed no statistically significant effect. All biostimulated treatments substantially outperformed unamended controls (2.4- to 2.7-fold higher removal). THB counts peaked around Day 28 before declining, and this bacterial fold-increase correlated significantly with TPH removal (r = 0.49, p = 0.0026), whereas fungal population growth did not (r = 0.01, p = 0.96). These findings indicate that soil texture, more than biostimulant identity, governs degradation outcome, and that bacterial rather than fungal proliferation drives hydrocarbon removal under these leaf-based biostimulation regimes.
    VL  - 1
    IS  - 3
    ER  - 

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Author Information
  • Department of Chemical/Petrochemical Engineering, Rivers State University, Port Harcourt, Nigeria

  • Department of Chemical/Petrochemical Engineering, Rivers State University, Port Harcourt, Nigeria

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