Bioremediation potential of soil microbes and field applications

Abstract

Which indigenous soil bacterial communities demonstrate greatest capacity for petroleum hydrocarbon degradation under Nordic climate conditions? This research evaluated bioremediation potential of microbial consortia isolated from contaminated industrial sites across southern Sweden over a 24-month field trial period. Soil samples were collected from six petroleum-contaminated locations representing diverse pollution histories and substrate compositions. Culture-dependent and metagenomic approaches identified 847 bacterial isolates belonging to 23 genera with confirmed hydrocarbon-degrading capabilities. Pseudomonas, Rhodococcus, and Mycobacterium species dominated functional communities, collectively representing 67.3% of isolated degraders. Laboratory microcosm experiments demonstrated total petroleum hydrocarbon reduction ranging from 34.7% to 89.2% over 90-day incubation periods depending on initial contamination levels and nutrient amendment strategies. Field-scale bioremediation trials at two pilot sites achieved 71.4% and 78.9% hydrocarbon removal over 18 months with bioaugmentation and biostimulation treatments respectively. Seasonal temperature fluctuations significantly influenced degradation kinetics, with rates declining 3.2-fold during winter months compared to summer periods. Metagenomic analysis revealed alkane hydroxylase and aromatic ring-hydroxylating dioxygenase genes as primary determinants of degradation capacity. These findings support implementation of indigenous microbial bioremediation strategies for petroleum-contaminated soils in temperate climate regions.