The effect of compost and Bacillus licheniformis on the phytoextraction of Cr, Cu, Pb and Zn by three brassicaceae species from contaminated soils in the Apulia region, Southern Italy

The selection of appropriate plant species is critical in the successful application of phytoremediation techniques. The present study is an attempt to assess the capability of three brassicaceae, Brassica alba (L.) Rabenh, Brassica carinata A. Braun and Brassica nigra (L.) Koch, for the phytoextraction of Cr, Cu, Pb and Zn from an unpolluted and polluted silty loamy soil added with either Bacillus licheniformis BLMB1 or compost or both. Experiments were conducted in a greenhouse in pots filled with the soils. In all experiments metals were shown to accumulate in shoots and roots of plants grown on polluted soils, and both compost and B. licheniformis BLMB1 strain were able to enhance the accumulation of metals, especially Cr. In particular, Cr accumulation in B. alba resulted higher than the Cr threshold for hyperaccumulator plants (1000 mg kg−1). This result provides a new plant resource that may have a potential use for phytoextraction of Cr from contaminated soil. However, because of the low bioconcentration factors (b1) for all studied metals, these species cannot be regarded as suitable for the phytoextraction of excessive Cr, Cu, Pb and Zn from polluted soils. Thus, these species may be used with success only for low metal polluted soils