Phenanthrene degradation by Beijerinckia sp. B8/36

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...

Degradation of pyrene byRhodococcus sp. UW1

“…The isolated strain was further characterized for the effect of environmental factors such as pH and temperature. In agreement with Strandberg et al (1986) and Weissenfels et al (1990), who studied the influence of pH and temperature on PAH degradation by pure bacterial cultures, pH 7.0 and 30°C were determined to be optimal for microbial growth and pyrene degradation.…”

Biodegradation of phenanthrene by Arthrobacter polychromogenes isolated from a contaminated soil

“…Environmental factors such as temperature have a greater influence on degradation of xenobiotics in soil and water (Sherill and Saylor 1980;Strandberg et al 1986). The results obtained by examining the influence of temperature on growth and degradation were supported by the observations of Weissenfels et al (1990), who also reported a decrease in growth of P. paucimobilis at 30°C, while phenanthrene degradation increased up to a temperature of 35 ° C.…”

“…Phenanthrene, which is composed of three fused benzene rings, is a relatively soluble PAH (Dzombak 1984) that can be degraded by m a n y microorganisms (Bumpus 1989;Ghosh and Mishra 1983;Guerin and Jones 1988a, b;Strandberg et al 1986). This paper deals with the characterization of phenanthrene degradation under different conditions by a pure bacterial culture isolated from a contaminated soil surrounding a former coking plant.…”

Indigo production by naphthalene-degrading bacteria

“…Naphthalene, salicylate and isopropyl-(-D-thiogalactopyranoside (IPTG) were added to the basal medium either alone or in combination, so as to induce the plasmidencoded genes. In case of the media supplemented with naphthalene, the MSM was prepared in naphthalene-saturated distilled water (Strandberg et al 1986). Salicylate and IPTG were added to the media at a ®nal concentration of 2 mmol l À1 and 1 mmol l À1 , respectively, for induction purposes.…”