EFFECT OF pH ON THE TOXICITY AND BIODEGRADATION OF PENTACHLOROPHENOL BY SPHINGOMONAS SP. STRAIN P5 IN NUTRISTAT CULTURE

Abstract

Abstract-A polychlorinated-phenol degrading bacterium, Sphingomonas sp. strain P5, was grown in nutristat culture (i.e., a continuous culture at a controlled substrate concentration) with pentachlorophenol (PCP) as the sole carbon and energy source. During steady state conditions, the effect of the medium pH on the growth of strain P5 on PCP was established. At lower pH values PCP exhibited a stronger toxicity than at higher pH values. Inhibition of the growth of strain P5 by PCP was correlated to the concentration of the undissociated phenol in the system, rather than to the dissociated or total PCP concentration. The results indicate that acidification of natural environments may enhance the toxicity of chlorophenols and suggest that treatments to increase environmental pH may reduce risk of chlorophenol toxicity at acidified sites.

Predominance of Char Sorption over Substrate Concentration and Soil pH in Influencing Biodegradation of Benzonitrile

“…Concave-downward patterns between degradation kinetics and soil pH are usually observed with neutral to weakly alkaline conditions favorable for the degradation by bacteria (Leahy & Colwell 1990;Rutgers et al 1998). We simply measured the degradation of benzonitrile at three pHs within the normal soil pH range, and did not provide information on the optimal pH for the degradation of benzonitrile.…”

Enhancement of Pentachlorophenol Biodegradation Using Organic and Inorganic Supports

“…At pH values lower than the pKa (4.75), this compound is mainly in its neutral form, easily adsorbed, and highly toxic. At pH values higher than the pKa, however, the pentachlorophenate ion predominates, which is much more soluble, less hydrophobic, and less toxic (Rutgers et al, 1998). The negatively charged pentachlorophenate ions are repelled by the soil particles or other solid supports that carry similar electrical charges (Christodoulatos et al, 1994).…”

Treatment of Bio-Oil Refinery Storm Water by a Simulated Constructed Wetland: A Sustainable Management Alternative

“…strain, Clostridium sp. is also know to biodegrade phenols (Panneton, Ramsay et al 1995;Rutgers, van Bommel et al 1998). Phenol biodegradation is sensitive to both pH and temperature, therefore in order to enhance the degradation pathways; it is recommended that an average pH of 6.3 and a temperature of 30 o C be maintained (PentaCouncil 1996;Rutgers, van Bommel et al 1998).…”