## 3 Results
### Analysis of Petroleum Hydrocarbons in Soil, Root and Shoot
Therefore, the uptake of lipophilic substances by plants is positively correlated with the lipid content of the root epidermis. Bioaugmentation of the soil with microbial consortia B1 and B2 allowed for the concentration of micro-organisms to be increased in the root zone of the phytoremediant used, which had a beneficial effect on the development of roots, and thus, the growth of _Echinacea purpurea_. In addition, it is likely that soil bioaugmentation increased the plant's production of surface-active compounds, such as small-molecule organic acids or polypeptides, capable of lowering surface tension and breaking down or converting complex organic compounds into simpler compounds with greater bioavailability [8; 9; 70; 71; 72; 73; 74]. Therefore, higher concentrations of TPH were determined in the analyzed plant material taken from systems inoculated with B1 and B2 microbial consortia. Moreover, the use of \(\gamma\)-PGA as an additive to microbial consortia made it possible to provide the plant with a readily available source of carbon and energy, which further influenced biomass production. It is also worth noting that some literature sources report that \(\gamma\)-PGA can be considered a biosurfactant, which affects the diffusion of xenobiotics into the root [75; 64; 76; 17]. Chromatographic analyses of the roots and shoots showed that extraction of aliphatic hydrocarbons from the soil to the root occurred most readily in systems 4 and 5, and 10 and 11. It should also be noted that in all systems tested, higher concentrations of TPH were obtained in the roots of _Echinacea purpurea_ than in the shoots. A summary of TPH concentrations in the roots and shoots of _Echinacea purpurea_ as a function of time and the system tested is provided in Figures 3 and 4. Figure 2: TPH content in soils after 3 and 6 months of phytoremediation process aided by bioaugmentation in the tested systems (System 1—soil DW + _E. purpurea_, System 2—soil DW + _E. purpurea_ + B1 microbial consortium, System 3—soil DW + _E. purpurea_ + B2 microbial consortium, System 4—soil DW + _E. purpurea_ + B1 microbial consortium with the addition of \(\gamma\)-PGA, System 5—soil DW + _E. purpurea_ + B2 microbial consortium with the addition of \(\gamma\)-PGA, System 6—soil DW + _E. purpurea_ + \(\gamma\)-PGA, System 7—soil OS + _E. purpurea_, System 8—soil OS + _E. purpurea_ + B1 microbial consortium, System 9—soil OS + _E. purpurea_ + B2 microbial consortium, System 10—soil OS + _E. purpurea_ + B1 microbial consortium with the addition of \(\gamma\)-PGA, System 11—soil OS + _E. purpurea_ + B2 microbial consortium with the addition of \(\gamma\)-PGA, System 12—soil OS + _E. purpurea_ + \(\gamma\)-PGA). Chromotographic analyses of the soils for polycyclic aromatic hydrocarbons confirmed the observations made during TPH analyses. The PAH concentration in systems not inoculated and inoculated with \(\gamma\)-PGA alone was the lowest, at 16.14% in Soil DW-1, 14.19% in Soil DW-6, 16.28% in Soil OS-1 and 18.20% in Soil OS-6. Phytoremediation assisted by bioaugmentation with B1 and B2 microbial consortia reduced PAH concentrations in the tested soils by 30.82% (Soil DW-2), 36.73% (Soil OS-3), 27.10% (Soil OS-2) and 31.07% (Soil OS-3). The use of \(\gamma\)-PGA as an additive to microbial consortia enabled an additional reduction in PAH concentrations in the tested soils, with biodegradation rates of 39.22% (Soil DW-4), 49.54% (Soil DW-5), 32.89% (Soil OS-4) and 37.55% (Soil OS-5). The changes in \(\Sigma\)PAH concentrations in SD and OS soils subjected to bioaugmentation-assisted phytoremediation are shown in Figure 5.