Toxicity of phenolic compounds to sediment bacteria.

Abstract

Biodegradation of organic compounds plays an important role in remediation of polluted environments. Several factors influence the rate and extent of biodegradation: number of degrading organisms, adequate supply of nutrients, adequate availability of a suitable electron acceptor. One important factor is the toxicity of the organic chemical itself. Very often chemicals may be susceptible to biodegradation at low concentrations, yet may be toxic to the degrading population at higher concentrations, thus inhibiting their own biodegradation. Phenolic compounds are known to exhibit toxicity to bacteria. Under batch conditions, a strain of Pseudomonas could degrade 0.1% phenol in approximately 48 hr, while taking over 130 hr to degrade 0.15% phenol. A concentration of 0.2% phenol was inhibitory to the cells, killing 50% of the inoculum within 10 d. Activated sludge bacteria maintained in pulse fed batch reactors were inhibited by concentrations of phenol in excess of 50 mg/L. Biodegradation of 4-chlorophenol by Alcaligenes sp. A 7-2 showed a similar concentration effect, being inhibited at concentrations above 160 mg/L in fed-batch culture. The present report is part of an investigation on the biodegradation of phenol in contaminated soils and sediments in northwestern Indiana. Phenol has been found in groundwater aquifers which drain intomore » the Grand Calumet watershed, and in groundwater contaminated by a Superfund site. Data on phenol toxicity were needed in order to assess the potential for in situ biodegradation of phenol and related compounds in sediments of the Grand Calumet River. 10 refs., 4 figs.« less