The main drawbacks of phytoremediation technology are storage and accumulation of pollutants in
the plant materials and the remediation process slowing down and often becoming inadequate when the
contaminated site has multiple pollutants [145]. The appropriate solution to these problems is to combine
the microbe-plant symbiosis within the plant rhizosphere [126] or to introduce microbes as endophytes
to allow degradation of pollutants within the plant tissues [137]. The microbial population in the
rhizosphere is much higher than present in vegetation-less soil, and this is due to the facilitation provided
by the plants through release of substances that are nutrients for microorganisms. This approach has been
evaluated under laboratory conditions, and if it succeeds in field conditions, this technology could
facilitate accelerated removal of pollutants, which in turn will support high plant biomass production for
bioenergy [146]. The major strategies for implementing bioremediation processes include biostimulation
and bioaugmentation approaches guided by specific microbes in combination with plants. Biostimulation
involves adding supplements to a contaminated site with the objective of stimulating growth of the
microbial population already present there, which may be capable of degrading the contaminants.
Bioaugmentation refers to addition of selected and acclimated microbial inocula to the environment that
do not contain microbes capable of degrading the contaminants.