Inducing Effect of Biosurfactants from Pseudomonas putida 12os Strain on Biodegradation of Hydrocarbons in Oil-Contaminated Soil

Abstract A major obstacle to optimizing soil bioremediation is the inability to monitor the molecular transformations of pollutants in situ. Traditional methods measure overall mass loss but provide little insight into the chemical restructuring of residual oil. This study proposes a methodology based on nuclear magnetic resonance spectroscopy (1H NMR) to directly monitor the dynamics of molecular changes in soil hydrocarbons using Haplic Chernozem soil artificially contaminated with crude oil at a concentration of 20 g/kg. Using this approach, we have demonstrated that biosurfactants produced by the strain Pseudomonas putida 12os act not only as emulsifiers, enhancing bioavailability, but also exert a selective influence on the native microbial community by stimulating the activity of specialized hydrocarbon degraders. NMR data revealed that the observed increase in resin content is in fact the accumulation of oxidation intermediates. Importantly, during the 63‑day experiment we recorded a sustained reduction in the content of persistent polyaromatic structures by 33% while simultaneously increasing the content of oxygenated compounds by 83%. This molecular shift was caused by biosurfactant-induced selective activation of key catabolic genes (alkM, GP-PAH), leading to community specialization in the sequential degradation of both aliphatic and aromatic hydrocarbons. The results confirm the effectiveness of NMR spectroscopy as a tool for studying bioremediation mechanisms and indicate that biosurfactants may act not only as emulsifiers for oils but also as modulators of the catabolic potential of the soil microbiome.