No abstract

The use of fossil fuels has greatly increased the ubiquity of polynuclear aromatic hydrocarbons (PAHs) in the environment, and their potential toxicity has generated considerable interest in the ability of microorganisms to utilize and/or detoxify these pollutants.One PAH of concern is phenanthrene. Numerous microbial species are known to degrade phenanthrene and there appear to be several metabolic routes available, depending upon the species, strain, and even the cultural conditions.',' Although there is a substantial amount of literature on the metabolic pathways of phenanthrene utilization, we have found surprisingly little information regarding the effects of environmental conditions on phenanthrene degradation rates. Such information would be of importance to understanding the fate of this compound in natural and controlled (i.e., wastewater treatment) biological systems.Gibson et aL3 isolated a strain of Beijerinckia from a polluted stream that was able to utilize biphenyl, naphthalene, anthracene, and phenanthrene as sole sources of carbon and energy. These same authors subsequently isolated a mutant, Beijerinckia sp. B8/36 which was able to only partially oxidize these compounds and as a result, required some other suitable substrate for growth. However, Shenill" found evidence for the mineralization of I4C-labeled phenanthrene with this strain when added to sterile and natural sediments. During preliminary experiments, we found the strain to be unable to grow solely on phenanthrene, but capable of growth and phenanthrene utilization when yeast extract was supplied. We shall discuss the effects of pH and temperature on growth and phenanthrene degradation by intact cells of Beijerinckia sp. B8/36. Cell growth and phenanthrene degradation (as evidenced by its disappearance) were studied in a buffered (0.1M potassium phosphate, pH 7.0) mineral salts solution containing 0.5 g/L yeast extract and ca. 0.6 mg/L ~henanthrene.~ Phenanthrene was incorporated into the medium as follows: 2 L distilled water were added to 0.2 L methanol containing 0.5% (w/v) phenanthrene. The mixture was then boiled to remove methanol. After cooling, the phenanthrene-water mixture was filtered twice through glass wool to remove undissolved phenanthrene. The resulting solution contained ca. 0.6 mg/L phenanthrene. The salts and yeast extract were added to this solution and the mixture sterilized at 121°C for 20 min. MATERIALS AND METHODSThe cells were cultured in the above medium (100 mL in 500 mL Erlenmeyer flasks, shaken in air, ca. 100 rpm, 30°C); and then an aliquot was transferred to fresh medium, equilibrated to the desired temperature, and to which varied amounts of mono-and dibasic potassium phosphate (0.1M final concentration) were added to obtain the desired pH. Samples were withdrawn at intervals from the experimental flask. The cell number was determined using a Petroff-Hauser and Helber microscope counting chamber. Phenanthrene was extracted from a 30-mL sample with 3.0 mL of glass-distilled hexane and quantified by gas c...

This report documents liquid low-level waste (LLLW) generation from 1986 through mid-1990. The report was written and submitted in draft form in 1990; however, it was not published in final form. Information contained within the report is accurate for the time it was written; however, several changes have been incurred in the LLLW system since that time. The report has not been updated to reflect these changes but is submitted as is to serve as a companion to report ORNI.Ff'MJ12638,

No abstract

No abstract