Antibiotic contamination in agricultural soils poses a growing threat to environmental health, crop safety, and ultimately human well-being. Among these contaminants, oxytetracycline (OTC), a widely used veterinary antibiotic, has drawn intense scrutiny due to its persistence in soils receiving manure application and wastewater irrigation. In a groundbreaking study published in the journal Biochar, a team of researchers from China unveils a novel, sustainable strategy to accelerate the breakdown of OTC residues while simultaneously limiting its uptake into plants, specifically lettuce. This approach centers on the synergistic application of biochar combined with carbohydrate-based carbon sources, a method that not only detoxifies the soil environment but also enhances plant resilience under antibiotic stress.
Biochar, a carbon-rich byproduct of biomass pyrolysis, has attracted attention for its multifunctional roles in soil remediation and fertility enhancement. Its porous structure, high surface area, and ability to adsorb contaminants make it a prime candidate for managing chemical residues like OTC. However, the innovation of this recent study lies in integrating biochar with different carbohydrate sources—namely glucose, sucrose, and starch—to create a conducive environment that fosters microbial activity and enzymatic degradation processes targeted at antibiotic compounds.
Under carefully controlled greenhouse experiments designed to simulate OTC-contaminated farmlands, the research team evaluated the efficacy of several treatments: biochar alone, biochar with glucose, biochar with sucrose, and biochar with starch. Lettuce plants were cultivated in these soils to examine both pollutant degradation and residue translocation into edible plant parts. The results revealed that biochar alone could enhance OTC degradation by an impressive 67%, notably curbing the antibiotic’s movement into lettuce leaves. However, when combined with carbohydrate amendments, the degradation rates soared, exhibiting nuanced effects depending on the sugar type.
The study demonstrated that glucose and sucrose, as rapidly metabolizable sugars, elicited immediate—but transient—surges in microbial respiration and enzymatic function, catalyzing accelerated OTC breakdown during early growth stages. However, these effects waned quickly due to the sugars’ swift consumption by soil microbes, leading to a plateau in degradation efficiency over time. Contrastingly, starch, a complex polysaccharide with slower biodegradability, delivered a prolonged release of carbon, sustaining microbial and enzymatic activity throughout the lettuce growth period. The biochar-starch treatment (BCST) outshone all others, achieving an impressive 92% OTC degradation and reducing the antibiotic’s half-life in soil to just eight days.
Moreover, BCST significantly boosted microbial biomass carbon by 55%, reflecting an enriched microbial community capable of continuous detoxification. This enhanced microbial presence plays a pivotal role in maintaining soil enzymatic functions such as oxidative enzymes and hydrolases, which directly participate in antibiotic molecular breakdown. These sustained biological activities underlie the superior performance of the BCST approach in managing antibiotic residues.
The benefits of this strategy extended beyond soil chemical remediation. Notably, OTC accumulation in both lettuce roots and leaves was markedly decreased under the BCST treatment, signifying improved food safety through reduced antibiotic translocation into edible tissues. Although plant biomass across treatments was statistically comparable, lettuce grown in BCST-amended soils exhibited higher nitrogen uptake efficiencies and elevated chlorophyll content. These physiological indicators suggest that BCST not only mitigates OTC toxicity but also fosters better nutrient assimilation and photosynthetic health, bolstering overall plant vigor in a contaminated environment.
Antibiotic pollution in farmland is widely attributed to manure and wastewater effluents, which introduce antibiotic residues that interfere detrimentally with soil microbial communities and plant physiology. Beyond reducing microbial diversity and activity, these residues contribute to a global concern: the propagation of antibiotic resistance genes within agricultural ecosystems. Strategies that enhance natural degradation pathways, such as the BCST method, provide dual advantages by detoxifying soils and potentially limiting resistance gene spread through the food web.
This research underscores the practicality of leveraging slow-release carbon sources like starch in combination with biochar as a soil amendment. Such a strategy champions ecological principles by harnessing native microbial capabilities rather than relying on chemical or physical remediation technologies, which often carry environmental drawbacks or cost barriers. The approach is adaptable, scalable, and conforms to sustainable agricultural practices, presenting an attractive option for farmers and land managers globally facing antibiotic-laden soils.
According to Dr. Qiang Zheng, the study’s corresponding author from China Agricultural University, the findings reveal a cost-effective and environmentally sound solution for antibiotic residue management. By supporting microbial communities and sustaining enzyme activities responsible for antibiotic degradation, the biochar–starch protocol offers a long-term pathway to rehabilitate contaminated soils and safeguard crop safety simultaneously.
Dr. Peiling Yang, co-corresponding author, further emphasizes the broader implications, stating that antibiotic pollution represents a dual threat to both agricultural sustainability and public health. The novel insight provided by their work points to soil remediation strategies capable of mitigating these intertwined challenges without compromising ecological integrity.
While the study’s greenhouse-scale results are promising, the authors acknowledge that extensive field trials are necessary to validate the method’s effectiveness across diverse agricultural contexts and environmental variables. Nonetheless, this research marks a significant progression in understanding how biochar-carbohydrate combinations can transform current approaches to mitigating antibiotic pollutants in soils.
Ultimately, the integration of biochar with starch sets a new paradigm for managing residual antibiotics in agroecosystems. Beyond its immediate benefits on degradation rates and reduced plant uptake, the approach fosters an enriched microbial soil environment and promotes healthier crop growth under contaminant stress. As antibiotic resistance and environmental contamination continue to escalate globally, innovative yet accessible strategies such as this offer hope for maintaining both agricultural productivity and ecological health.
Subject of Research: Not applicable
Article Title: Enhancing oxytetracycline degradation and reducing its transfer to lettuce using biochar combined with carbohydrate carbon sources
News Publication Date: 2-Sep-2025
Web References: 10.1007/s42773-025-00502-x
References: Zeng et al. “Enhancing oxytetracycline degradation and reducing its transfer to lettuce using biochar combined with carbohydrate carbon sources.” Biochar (2025).
Image Credits: Jiefeng Zeng, Xiao Wang, Xin He, Zhanyi Gao, Feiyang Zeng, Qiang Zheng & Peiling Yang
Keywords: Enzymes, Antibiotics, Soils
