Nicotine, a potent environmental pollutant, accumulates to concerning levels in soils subjected to long-term tobacco monoculture, posing significant risks to ecosystems and human health. To combat this, the isolation and utilization of nicotine-degrading bacteria have become a crucial remediation strategy. In a recent study published in Environment International, Xuanquan Zhu, Meng Jia, Weiyu Zhou, Peng Zhou, Yu Du, Huanwen Yang, Ge Wang, Yuxiang Bai, and Na Wang investigated the effectiveness of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More loaded with nicotine-degrading bacteria for enhancing degradation efficiency and promoting synergistic interactions with native microorganisms.

The researchers successfully isolated a nicotine-degrading strain, Paenarthrobacter ureafaciens N21 (N21), from tobacco-cultivated soils. Whole-genome sequencing revealed that N21 primarily breaks down nicotine through the pyridine pathway. This process is visually indicated by a distinctive color change in the culture medium from colorless to blue, then brown.

To enhance its degradation efficiency and field applicability, N21 was immobilized onto tobacco stem-derived biochar, creating a composite material named BN21. The biochar, produced at 600±5∘C with a 6-hour dwell time, exhibited alkaline properties (pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More 10.53) and abundant internal cavities. After 48 hours of co-culture, the bacterial concentration on the biochar reached an impressive 5.44×1010 copies/g. This immobilization led to a 1.6-fold increase in the biochar’s specific surface area, although micropore surface area, pore volume, and mesopore diameter decreased by 79.61%, 58.82%, and 59.10% respectively, likely due to bacterial secretions. Functional groups on the biochar surface also played a role in microbial attachment. Under laboratory conditions, BN21 composites demonstrated exceptional nicotine removal, achieving 99.32% degradation.

Soil incubation experiments further validated these findings, showing that BN21 achieved 1.4 times higher nicotine degradation efficiency compared to free N21. This enhanced efficiency is attributed to the biochar’s ability to promote rapid adaptation and increase bacterial numbers in the soil. Unlike direct inoculation, which can lead to rapid population collapse of introduced microbes, BN21 significantly accelerated N21 colonization in soil (P<0.0001). The biochar’s porous structure and large surface area create a protective microenvironment for the bacteria, reducing competition with native soil microbes and providing supplementary trace nutrients, thereby enhancing bacterial colonization rates and accelerating nicotine degradation.

The introduction of BN21 significantly altered both the soil’s bacterial and fungal community structures, leading to reduced diversity but increased stability against nicotine contamination. BN21 specifically enriched nicotine-degrading microbes like Pseudomonas (involved in the pyrrolidine pathway) and Sphingomonas (involved in a variant of the pyridine and pyrrolidine pathway), while the N21 strain itself belongs to the Paenarthrobacter genus, which is also linked to the pyridine degradation pathway. Metabolomic analyses confirmed that BN21 enriched pathways crucial for nicotine metabolism, such as nicotinate and nicotinamide metabolism. The detection of 3-succinoylpyridine, a key breakdown product in nicotine’s pyrrolidine pathway, at significantly higher levels in BN21-treated soil, suggests that BN21 not only activates N21-associated pyridine pathways but also enhances native microbial activity to promote pyrrolidine pathway-mediated nicotine degradation.

Crucially, BN21 maintained stable degradation capacity across various simulated habitat conditions, demonstrating robust tolerance to temperature fluctuations, soil type variations (red, yellow, paddy soil), and different nicotine concentration gradients (1, 5, 10 mg/kg). This broad-spectrum environmental adaptability provides reliable experimental evidence for its practical application in environmental remediation.

This study highlights the novel strategy of using bacteria-loaded biochar for targeted pollutant removal, suggesting broader applications for addressing emerging organic contaminants in ecological remediation. The findings provide critical insights for developing microbiome-based green technologies for environmental management and sustainable practices.

Source: Zhu, X., Jia, M., Zhou, W., Zhou, P., Du, Y., Yang, H., Wang, G., Bai, Y., & Wang, N. (2025). Biochar loaded with nicotine-degrading bacteria works synergistically with native microorganisms to efficiently degrade nicotine. Environment International, 109550.