Bacterial assisted phytoremediation of heavy metals and organic pollutants by Cannabis sativa as accumulator plants growing on distillery sludge for ecorestoration of polluted site

The aim of the study is to explore the potential rhizospheric bacterial communities associated with Cannabis sativa L. (Cannabis); growing on the complex pollutant-rich distillery sludge. Seven bacterial species were isolated, among which four potential bacterial species were characterized based on the 16s rRNA sequencing from the rhizosphere sludge of C. sativa; they are Bacillus thuringiensis (MW887525), Bacillus cereus (MW887524), Achromobacter denitrificans (MW886333), Bacillus subtilis (MW886231). The isolated bacteria showed PGPR attributes and potential for ligninolytic enzyme activity. Further, to correlate these bacteria with organic pollutants of sludge, the GC-MS analysis of fresh disposed distillery sludge and after growth of 30 and 60 days C. sativa was also analysed, which showed the conversion and disappearance of compounds by the activity of rhizospheric bacterial communities. Additionally, C. sativa showed a higher metal accumulation pattern of Fe (801.81 +/- 0.123)> Cu (275.086 +/- 0.069)> Zn (162.15 +/- 0.085)> Mn (63.92 +/- 0.093)> Pb (28.619 +/- 0.192)> Ni (5.02 +/- 0.078)> Cd (2.53 +/- 0.085)> Cr (1.87 +/- 0.079) mg kg -1 in their shoot, root followed by leaf. The plant also showed BCF >1 and TF > 1 for most of the metals. Thus, this showed the phytoextraction properties of C. sativa from distillery sludge polluted sites. The findings of this study will enable to understand the functional role of rhizospheric bacterial community for the detoxification and degradation of complex organometallic waste, and will thus aid in the development of adequate phytoremediation techniques for the eco-restoration of polluted industrial sites for sustainable development.

Automated summary

The aim of this study was to explore the potential rhizosphere bacterial communities associated with Cannabis sativa growing on distillery sludge. Four potential bacterial species were characterized and shown to have attributes of plant growth-promoting rhizobacteria and ligninolytic enzyme activity. Furthermore, the study analyzed the conversion and disappearance of organic compounds in the distillery sludge due to the activity of the bacterial communities. The results indicate the phytoextraction properties of C. sativa for pollutants in the sludge.