Bioremediation bacteria to protect plants in pentachlorophenol-contaminated soil

Plants may be useful in stabilization and remediation of polluted surface soils, but phytotoxicity and plant bioconcentration of some pollutants can interfere with plant-associated site remediation. Pseudomonas strain SR3, when applied to seeds of prose millet (Panicum miliaceum L.), protected the growing plants from phytotoxicity of pentachlorophenol (PCP) in the soil during a 4-wk growth-chamber study. Untreated plants in the contaminated soil grew very poorly. In soil receiving the bacteria-treated seed, PCP was reduced from 175 mg/kg to 3 mg/kg. When bacteria were mixed thoroughly into the soil at 5 x 10(6) cfu/g, in the absence of plants, PCP was likewise reduced from 175 to 5 mg/kg. PCP in soil with noninoculated plants remained at the initial level (165 mg/kg extractable PCP). Roots without applied bacteria concentrated PCP from the soil into root tissue to a ratio of 13:1 (final root concentration/initial soil concentration), whereas the bacteria-treated roots concentrated PCP at a ratio of 0.09:1.