Isolation and characterization of dibenzofuran-degrading bacteria

Abstract

Two bacterial strains capable of utilizing dibenzofuran (DF) as a sole carbon source were isolated from soil samples of reclaimed land. The strains designated HL1 and HL7 were identified as Klebsiella sp. and Sphingomonas sp., respectively, on the basis of biochemical characteristics and the sequences of the 16S ribosomal DNA. Sphingomonas sp. strain HL7 degraded non-, mono- and also dichlorinated DF and dibenzo-p-dioxin (DD). Klebsiella sp. strain HL1 was able to degrade non- and monochlorinated DFs and DDs, but not dichlorinated ones. The metabolites formed from DF by strains HL1 and HL7 were similar to those by dioxin-degrading bacteria Sphingomonas sp. strain RW1 except for salicylic acid and catechol. Strain HL7 had a gene homologous to that encoding the dioxin dioxygenase alpha-subunit (dxnA1) gene of Sphingomonas sp. strain RW1. However, Southern hybridization analysis showed that the size of an EcoRV-digested genomic fragment involving the dioxin dioxygenase gene of strain HL7 was smaller than that of strain RW1, and that strain HL1 did not have the homologous gene. Strains HL1 and HL7 provided useful information regarding the dioxygenase genes.

Diversity of hydrocarbon-degradingKlebsiellastrains isolated from hydrocarbon-contaminated estuaries

“…HL1. The HL1 strain was described as being capable of degrading non-and monochlorinated dibenzofuran and dibenzop-dioxin, and was found to possess dioxygenase genes (Fukuda et al 2002). Furthermore, none of the strains isolated in this study were similar to any previously described hydrocarbon-degrading Klebsiella species, such as Klebsiella sp.…”

“…Klebsiella appears to have substantial potential for the biodegradation of diverse pollutants, such as organophosphorous (4-methylsulfinyl phenol) and halogenated aromatic compounds (3,5-dibromo-4-hydrobenzonitrile), which are present in herbicides and pesticides (Mac Rae and Cameron 1985;McBride et al 1986), trifluralin (Bellinaso Mde et al 2004), nitroaromatic compounds (Kim and Song 2005), 1,2-dichloroethane (Mileva et al 2008), 4-chloroaniline (Vangnai and Petchkroh 2007), monochlorinated dibenzofuran and dibenzo-p-dioxin (Fukuda et al 2002).…”

Matter-enhanced transition probabilities in quantum field theory

“…Flavor oscillations are observed at T ≫ τ and are computed with S[∞]. Neutrino's mass squared differences were determined from experiments [16][17][18][19][20][21] of using neutrinos from the sun, accelerators, reactors, and atmosphere as [22],…”

Genetic characterization of the dibenzofuran-degrading Actinobacteria carrying thedbfA1A2gene homologues isolated from activated sludge

“…0.1% DF. If Rhodococcus strains are preferentially isolated under these conditions because of their rapid growth (doubling times of R. opacus strain SAO101 and S. wittichii strain RW1 with DF were 6 h [12] and 7 h [7], respectively), this can explain why most DF-degrading bacteria isolated from natural soil or activated sludge samples exhibit a surprising uniformity in their phenotypes and cell structures [24]. When the same samples as those used in this study were cultured in the medium containing crystal violet to inhibit Gram-positive bacteria, we could not obtain Gram-negative DF-degrading bacteria (data not shown).…”

“…For example, 2,3,7,8-tetrachlorodibenzo-p-dioxin, the biologically most active and toxic member of this class of compounds has a wide variety of species-and tissue-specific effect, such as tumor promotion, immuno-, hepato and dermal toxicity, lethality, birth defects, endocrine disruption and induction of numerous enzymes [1,2]. Dibenzo-p-dioxin (DD) and dibenzofuran (DF) are used as model compounds of dioxins for microbial degradation, and several bacteria capable of assimilating DD and DF have been described [3][4][5][6][7][8][9][10]. 0378 Some of these bacteria have also been reported able to degrade chlorinated DDs and DFs [7,[10][11][12][13][14].…”