- Degradation of Gaseous BTX by Biofiltration with Phanerochaete chrysosporium
-
Oh, Young Sook , Choi, Sung Chan , Kim, Yeong Kwan
-
J. Microbiol. 1998;36(1):34-38.
-
-
-
 Abstract
 PDF
-
Biodegradation of benzene, toluene, and o-, m-, p-xylenes(BTX) by the white rot fungus, Phanerochaete chrysosporium was studied in a biofilter. P. chrysosporium was cultured under shaking conditions on YMG growth medium and homogenized pre-grown cells were transferred to biofilter. A preliminary batch culture experiment showed that all BTX components were degraded simultaneously without any observable substrate interactions, while the rate constant was the highest for p-xylene and lowest for benzene. For the biofiltration of the BTX, the BTX compounds were individually vaporized from 3 glass bottles containing benzene, toluene, and xylenes, respectively, by applying air flow. The vaporized fluxes of the compounds were immediately taken by the air current to the biofilter through the horizontal tube at the rim of the source other than the pollutants themselves. The effect of air flow rate (0.026~0.450 l/h) on the degradation of the compounds was evaluated in the biofilter packed with glass beads. A substantially higher degradation of all the BTX compounds was observed at higher flow rates, suggesting that mass transfer is a limiting factor in the degradation process. At a flow rate of 0.026l/h, there was no substantial difference in the extent of degradation between the two support media.
- Characterization of BTX-degrading bacteria and identification of substrate interactions during their degradation
-
Oh, Young Sook , Choi, Sung Chan
-
J. Microbiol. 1997;35(3):193-199.
-
-
-
Abstract
PDF
-
From several industrial wastewaters, 14 bacterial strains which degrade benzene, toluene, o-xylene, m-xylene, or p-xylene (BTX) were obtained. These strains were characterized as to their species composition and the substrate range, kinetic parameters and the substrate interactions were investigated. Although BTX components have a similar chemical structure, isolated strains showed different substrate ranges and kinetic parameters. None of the strains could degrade all of BTX components and most of them showed an inhibition (Haldane) kinetics on BTX, BTX mixtures were removed under inhibitory substrate interactions with variation in the intensity of inhibition. For a complete degradation of BTX, a defined mixed culture containing three different types of pathways was constructed and all of the BTX components were simultaneously degraded with the total removal rate of 225.69 mg/g biomass/h Judging from the results, the obtained mixed culture seems to be useful for the treatment of BTX-contaminated wastewater or groundwater as well as for the removal of BTX from the contaminated air stream.
- Reduction of hexavalent chromium by pseudomonas aeruginosa HP014
-
Oh, Young Sook , choi, Sung Chan
-
J. Microbiol. 1997;35(1):25-29.
-
-
-
Abstract
PDF
-
Microbial reduction of hexavalent (VI) to trivalent (III) chromium decreases its toxicity by two orders of magnitude. In order to investigate the nature of Cr-reduction, Cr-resistant Pseudomonas aeruginosa HP014 was isolated and tested for its reduction capability. At the concentration of 0.5 mM Cr(VI), cell growth was not inhibited by the presence of Cr(VI) in a liquid medium, and Cr(VI) reduction was accompanied by ell growth. When cell-free extract was tested, the reduction of Cr(VI) showed a saturation kinetics with the maximum specific activity of 0.33 umol min^-1 mg^-1 cell protein, and an apparent K. of 1.73 mM Cr(VI). The activity required either NADH or NADPH as an electron donor. However, NADPH gave 50% as much activity as NADH. To locate the reductase activity, cell free extract was centrifuged at 150,000×g, and subsequently the supernatant and pelleted membrane fractions were tested for Cr(VI) reduction activity. The supernatant of the centrifugation showed almost the same Cr(VI) reduction activity as compared with that of the cell-free extract, indicating that the Cr(VI)-reducing activity of P. aeruginosa HP-14 is due to soluble enzyme. Moreover, the activity appeared to be the highest among the known activities, suggesting that the strain might be useful for remediation of Cr(VI)-contaminated sites.
|
MSK
