Microbial Biotechnology for Accelerated Remediation of War-Affected Soils. Part 1: Soil Recovery Following Shell Explosions

Abstract

In regions of Ukraine affected by active hostilities, large areas of arable land have been severely damaged and require urgent remediation. This research aimed to assess the microbial disruption level in soils impacted by military actions – specifically shell explosions – and to develop a biotechnology for their accelerated restoration using microbial bioformulations. Methods. Microbiological methods encompassed the cultivation of microorganisms for obtaining bioformulations and  quantitative assessment of ecological-trophic groups through soil suspension plating on selective agar media. Ecological indices were calculated as the ratio of microbial abundance on soil or starch-ammonium agar to that on meat-peptone agar. Metagenomic analysis of soil samples was performed using high-throughput sequencing on an Illumina MiSeq platform. Model vegetation experiments involved the application of microbial formulations to soil and  cultivation of white clover as a phytoremediator species. Field trials were carried out to evaluate the effectiveness of remediation strategies under real-world conditions. The content of the explosive compound hexahydro-1,3,5-trinitro-1,3,5-triazine in soil was determined using colorimetric methods and liquid chromatography coupled with mass spectrometry (LC-MS). Results. Shell explosions significantly inhibited soil microbial activity due to mechanical disruption and toxic contamination. The greatest declines were observed in nitrogen-fixing (3.2-fold), phosphate-mobilizing (6-fold), and cellulolytic (2.8-fold) microorganisms and streptomycetes (2.9-fold), which are proposed as bioindicators of soil disturbance. To address this, a bioremediation strategy was developed combining microbial soil detoxification with phytoremediation using white clover (Trifolium repens) inoculated with microbial bioformulations to enhance stress tolerance. This approach mitigated pollutant effects, promoting functional and taxonomic diversification of soil prokaryotes. As toxicity decreased, an abundance of pollution-resistant Bacilli declined, while representation of sensitive taxa such as Actinobacteria and Alphaproteobacteria increased by 1.4-fold and 1.8-fold, respectively. The biotechnology proved highly effective in restoring beneficial microbiota, rebalancing rhizospheric communities and supporting stable plant growth. Field trials confirmed its robustness for remediating soils contaminated by explosive residues. Conclusions. Shell explosions significantly suppressed soil microbiota, with nitrogen-fixing, phosphate-mobilizing, cellulose-degrading microorganisms and streptomycetes being the most affected – making them suitable indicators for microbiomonitoring. Ecological analysis revealed inhibited nitrogen and carbon cycling and reduced humus formation. Prokaryotic shifts showed increased dominance of resistant Bacilli. A combined bioremediation approach using microbial bioformulations and phytoremediation restored beneficial microbiota within 60 days, rebalanced microbial communities, and improved soil biochemical functions and diversity.