Thermophilic biodegradation of BTEX by two Thermus Species

Abstract

Two thermophilic bacteria, Thermus aquaticus ATCC 25104 and Thermus species ATCC 27978, were investigated for their abilities to degrade BTEX (benzene, toluene, ethylbenzene, and xylenes). Thermus aquaticus and the Thermus sp. were grown in a nominal medium at 70 degrees C and 60 degrees C, respectively, and resting cell suspensions were used to study BTEX biodegradation at the same corresponding temperatures. The degradation of BTEX by these cell suspensions was measured in sealed serum bottles against controls that also displayed significant abiotic removals of BTEX under such high-temperature conditions. For T. aquaticus at a suspension density of only 1.3 x 10(7) cells/mL and an aqueous total BTEX concentration of 2.04 mg/L (0.022 mM), benzene, toluene, ethylbenzene, m-xylene, and an unresolved mixture of o-and p-xylenes were biodegraded by 10, 12, 18, 20, and 20%, respectively, after 45 days of incubation at 70 degrees C. For the Thermus sp. at a suspension density of 1.1 x 10(7) cells/mL and an aqueous total BTEX concentration of 6.98 mg/L (0.079 mM), benzene, toluene, ethylbenzene, m-xylene, and the unresolved mixture of o-and p-xylenes were biodegraded by 40, 35, 32, 33, and 33%, respectively, after 45 days of incubation at 60 degrees C. Raising the BTEX concentrations lowered the extents of biodegradation. The biodegradations of both benzene and toluene were enhanced when T. aquaticus and the Thermus sp. were pregrown on catechol and o-cresol, respectively, as carbon sources. Use of [U-(14)C]benzene and [ring-(14)C]toluene verified that a small fraction of these two compounds was metabolized within 7 days to water-soluble products and CO(2) by these nongrowing cell suspensions. Our investigation also revealed that the nominal medium can be simplified by eliminating the yeast extract and using a higher tryptone concentration (0.2%) without affecting the growth and BTEX degrading activities of these cells. (c) 1995 John Wiley & Sons, Inc.

Characterization of a Novel Thermostable Mn(II)-dependent 2,3-Dihydroxybiphenyl 1,2-Dioxygenase from a Polychlorinated Biphenyl- and Naphthalene-degrading Bacillus sp. JF8

“…To be able to rationally engineer such properties into mesophilic enzymes, a study of the determinants of the stability is an important task for basic and applied research. Although thermophiles degrading aromatic compounds such as BTEX (benzene, toluene, ethylbenzene, xylene isomers) and phenol/cresol have been isolated (19,20,21), the aromatic pathways in these organisms are not well studied, and there have been few reports on the characterization of the genes/proteins involved (22,23).…”

Toxicological Profile for Ethylbenzene

“…Furthermore, degradation was greater at 25 °C than at 37 °C, but pH variations between 4.5 and 7 had little effect on the extent of the degradation. Chen and Taylor (1995) reported that two thermophilic bacterial strains, Thermus aquaticus and an unidentified Thermus sp. degraded ethylbenzene (in a mixture with other BTEX chemicals) by 18% after 45 days of incubation at 70 °C and by 32% after 45 days of incubation at 60 °C, respectively.…”

“…The partitioning and transport processes in water, soil, and aquatic life are also well characterized (ASTER 1995;Dewulf et al 1996;Kawamura and Kaplan 1983;Ligocki et al 1985;Swann et al 1983). Transformation and degradation processes have also been well characterized in air (Atkinson and Carter 1984;Atkinson et al 1978;Grovenstein and Mosher 1970;Herron and Huie 1973;Hoshino et al 1978;O'Brien et al 1975;Ohta and Ohyama 1985;Ravishankara et al 1978;Yanagihara et al 1977), water (Acton and Barker 1992;Anid et al 1993;Bouwer and McCarty 1984;Burback and Perry 1993;Ehrhardt and Petrick 1984;Gschwend et al 1982;Hutchins 1991;Masten et al 1994;Wakeham et al 1983;Wilson et al 1986), and in soil and sediment (Bestetti and Galli 1984;Chen and Taylor 1995;Hutchins 1991;Hutchins et al 1991;Jamison et al 1970;Ramanand et al 1995;Van der Linden and Thijsse 1965;Yadav and Reddy 1993;Zappi et al 1996). No data need is identified at this time.…”

Reducing Emissions of Volatile Organic Compounds - Final Report - 08/15/1997 - 02/14/2001

“…Biodegradation at 50 o C to 70 o C by several Bacillus strains in batch studies has been reported for methanol (AlAwadhi et al 1989;Dijkhuizen and Artman 1990;Arfman et al 1992;Arfman et al 1992). Biodegradation of BTEX compounds at 45 o C to 77 o C by a Thermus species in a batch reactor has been demonstrated (Chen and Taylor 1995;Chen and Taylor 1997).…”