FACTORS INFLUENCING THE SURVIVAL AND ACTIVITY OF A PENTACHLOROPHENOL-DEGRADING Flavobacterium sp. IN SOIL SLURRIES

Abstract

The effects of soil type, supplementation with carbon or inorganic nutrients, creosote, and copper/chromate/arsenate (CCA) mixtures, on viability and pentachlorophenol (PCP) degradation by inoculants of a PCP-degrading Flavobacterium sp. were examined in phosphate-buffered soil slurries. Populations of 108Flavobacterium/mL in non-sterile slurries prepared with clay loam, silt loam, or loamy sand declined by at least 95% within 3 d. Populations were stable for at least a week in heat-sterilized clay loam slurries but addition of non-sterile soil resulted in rapid death of the Flavobacterium sp. Supplementation with 4 g L−1 Na-glutamate or glucose, promoted the growth of the Flavobacterium sp. in non-sterile clay loam slurries. Supplementation with 1 g L−1 Na-glutamate, glucose, or p-hydroxybenzoate stimulated PCP degradation when the Flavobacterium sp. was inoculated at ≥ 108 cells mL−1 and the PCP concentration was less than 150 mg L−1. Addition of [Formula: see text], [Formula: see text], Mg2+, and Fe2+ together did not stimulate growth. Populations of culturable indigenous bacteria were larger in soil containing 50–300 mg L−1 PCP than in controls. Addition of PCP favored the predominance of one colony type identified as a pseudomonad. Creosote of CCA mixtures, pollutants often found together with PCP contamination, were inhibitory to the Flavobacterium sp. in soil extract. Key words: Pentachlorophenol, biodegradation, Flavobacterium, soil slurries