Microbial assisted phytoextraction of Cd2+ by Salix viminalis under in vitro culture conditions

Microbially assisted phytoremediation is considered as the most promising eco-friendly solution for recultivation of heavy metal polluted soils. In vitro experiments can be favorable systems that allow assessing compatibility and efficiency of both partners (e.g. plant-microorganism) which reduces time and space in the initial stages of this technology. The main objective of this study was: (1) to calculate the Cd2+ accumulation factors (e.g. BCF, Ti, AF) using willow (Salix viminalis L.) inoculated with three Streptomyces sp. strains under in vitro conditions and (2) to compare obtained results with that derived from pot experiments by Złoch et al. (2017). Our results reveal significantly increase in Cd2+ accumulation capacity of Streptomyces spp. inoculated willow plants, indicating microbial stimulation of phytoextraction. Additionally, inoculated plants showed higher biomass production and lower lipids peroxidation level. The results revealed significant increase of MEA, BCF, Ti, MER by Strep-1 and Strep-2 in the above-ground parts of inoculated plants. Moreover, of the three strains tested, Strep-1 (Streptomyces sp. SIIB-Zn-R8) demonstrated the highest impact on the Cd2+ phytoextraction efficiency. In conclusion, the proposed in vitro model system allowed predicting Cd2+ phytoextraction capacity performed using inoculated willow plants with the significant reduction of both time and space.