Immobilization of metribuzin-degrading bacteria on biochar: Enhanced soil remediation and bacterial community restoration

Abdul Qadeer Wahla; Samina Anwar; Muhammad Irfan Fareed; Wasiq Ikram; Liaqat Ali; Hesham F Alharby; Atif A Bamagoos; Afaf A Almaghamsi; Samina Iqbal; Shafaqat Ali

doi:10.3389/fmicb.2022.1027284

Immobilization of metribuzin-degrading bacteria on biochar: Enhanced soil remediation and bacterial community restoration

Front Microbiol. 2023 Feb 15:13:1027284. doi: 10.3389/fmicb.2022.1027284. eCollection 2022.

Authors

Abdul Qadeer Wahla¹, Samina Anwar¹, Muhammad Irfan Fareed², Wasiq Ikram^{3

3}, Liaqat Ali⁴, Hesham F Alharby^{5

6}, Atif A Bamagoos⁵, Afaf A Almaghamsi⁷, Samina Iqbal¹, Shafaqat Ali^{8

9}

Affiliations

¹ Soil and Environmental Biotechnology Division, National Institute for Biotechnology and Genetic Engineering College, Pakistan Institute of Engineering and Applied Sciences (NIBGE-C, PIEAS), Faisalabad, Punjab, Pakistan.
² Department of Life Sciences, School of Science, University of Management and Technology, Johar Town, Lahore, Pakistan.
³ School of Botany, Minhaj University Lahore (MUL), Lahore, Pakistan.
⁴ Department of Soil and Environmental Sciences, University of Agriculture Faisalabad, Sub Campus Burewala, Vehari, Pakistan.
⁵ Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
⁶ Plant Biology Research Group, Department of Biological Sciences, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
⁷ Department of Biology, College of Science, University of Jeddah, Jeddah, Saudi Arabia.
⁸ Department of Environmental Science, Government College University, Faisalabad, Pakistan.
⁹ Department of Biological Sciences and Technology, China Medical University, Taichung, Taiwan.

Abstract

Metribuzin (MB), a triazinone herbicide is extensively sprayed for weed control in agriculture, has been reported to contaminate soil, groundwater, and surface waters. In soil, MB residues can negatively affect not only the germination of subsequent crops but also disturb soil bacterial community. The present study describes the use of biochar as a carrier material to immobilize MB-degrading bacterial consortium, for remediation of MB-contaminated soil and restoration of soil bacterial community in soil microcosms. The bacterial consortium (MB3R) comprised four bacterial strains, i.e., Rhodococcus rhodochrous AQ1, Bacillus tequilensis AQ2, Bacillus aryabhattai AQ3, and Bacillus safensis AQ4. Significantly higher MB remediation was observed in soil augmented with bacterial consortium immobilized on biochar compared to the soil augmented with un-immobilized bacterial consortium. Immobilization of MB3R on biochar resulted in higher MB degradation rate (0.017 Kd^-1) and reduced half-life (40 days) compared to 0.010 Kd^-1 degradation rate and 68 day half-life in treatments where un-immobilized bacterial consortium was employed. It is worth mentioning that the MB degradation products metribuzin-desamino (DA), metribuzin-diketo (DK), and metribuzin desamino-diketo (DADK) were detected in the treatments where MB3R was inoculated either alone or in combination with biochar. MB contamination significantly altered the composition of soil bacteria. However, soil bacterial community was conserved in response to augmentation with MB3R immobilized on biochar. Immobilization of the bacterial consortium MB3R on biochar can potentially be exploited for remediation of MB-contaminated soil and protecting its microbiota.

Keywords: Bioaugmentation; Biodegradation; Metagenomics analysis; Rice-husk biochars; Soil Bacterial diversity.