EFFECT OF HYBRID POPLAR TREES ON MICROBIAL-POPULATIONS IMPORTANT TO HAZARDOUS-WASTE BIOREMEDIATION

Microbial concentrations of denitrifiers, pseudomonads, and monoaromat ic petroleum hydrocarbon (BTX) degraders were significantly higher (p < 0.1) in soil samples from the rhizosphere of poplar trees than in ad jacent agricultural soils, and atrazine degraders were found only in o ne rhizosphere sample. The relative abundance of these phenotypes (as a fraction of total heterotrophs) was not significantly different betw een rhizosphere and surrounding soils. Therefore, the poplar rhizosphe re enhanced the growth of microbial populations that participate in na tural bioremediation without exerting selective pressure for them.