To examine the trichloroethylene (C2HCl3)-degrading capability of five microorganisms, the maximum rate, extent, and degree of C2HCl3 mineralization were evaluated for Pseudomonas cepacia G4, Pseudomonas cepacia G4 PR1, Pseudomonas mendocina KR1, Pseudomonas putida F1, and Methylosinus trichosporium OB3b using growth conditions commonly reported in the literature for expression of oxygenases responsible for C2HCl3 degradation. By varying the C2HCl3 concentration from 5 microM to 75 microM, Vmax and Km values for C2HCl3 degradation were calculated as 9 nmol/(min mg protein) and 4 microM for P. cepacia G4, 18 nmol/(min mg protein) and 29 microM for P. cepacia G4 PR1, 20 nmol/(min mg protein) and 10 microM for P. mendocina KR1, and 8 nmol/(min mg protein) and 5 microM for P. putida F1. This is the first report of these Michaelis-Menten parameters for P. mendocina KR1, P. putida F1, and P. cepacia G4 PR1. At 75 microM, the extent of C2HCl3 that was degraded after 6 h of incubation with resting cells was 61%-98%; the highest degradation being achieved by toluene-induced P. mendocina KR1. The extent of C2HCl3 mineralization in 6 h (as indicated by concentration of chloride ion) was also measured and varied from 36% for toluene-induced P. putida F1 to 102% for M. trichosporium OB3b. Since C2HCl3 degradation requires new bio-mass, the specific growth rate (mu max) of each of the C2HCl3-degradation microorganisms was determined and varied from 0.080/h (M. trichosporium OB3b) to 0.864/h (P. cepacia G4 PR1).

. 1998. Corrosion inhibition of SAE 1018 steel by Pseudomonas fragi and Escherichia coli biofilms has been evaluated using batch cultures in rich medium (LB) and seawater-mimicking medium (VNSS) at 23°C and 30°C with or without daily medium replenishment. Biofilm components have been stained simultaneously for polysaccharide (calcofluor) and live and dead cells (Live/Dead Baclit viability kit) and visualized using confocal scanning laser microscopy (CSLM). Image analysis was used to quantify the relative proportions of live cells, dead cells, polysaccharide and void space in the biofilm. This staining technique and examination of the architecture of biofilms responsible for inhibiting metal corrosion revealed that both Ps. fragi and E. coli produce polysaccharide only in the seawater medium; in rich medium, the biofilm consisted mainly of a layer of sessile cells near the biofilm-metal interface and sparse thick clumps of cells at the biofilm-liquid interface. Biofilms of both strains had a higher proportion of live cells in the rich medium than in the seawater-mimicking medium at the higher temperature, and more live cells were present at the higher temperature for LB medium. The corrosion inhibition observed (2·3-6·9-fold in 8 d) was not significantly affected by medium type or replenishment. Increase in the cellular content of the biofilms, as a result of increasing temperature, led to a reduction in corrosion.

An aerobic, single-pass, fixed-film bioreactor become an important compound for hazardous waste was designed for the continuous degradation and minerremediation (McFarland et al., 1992; Nyer and Moralization of gas-phase trichloroethylene (TCE). A pure cul- ello, 1993;Wilcox et al., 1995), and numerous bioture of Burkholderia cepacia PR1 23 (TOM 23C ), a Tn5 transporeactor designs have been studied for its degradation son mutant of B. cepacia G4 that constitutively expresses (Fathepure and Vogel, 1991; Folsom and Chapman, 1991; the TCE-degrading enzyme, toluene ortho-monooxygenase (TOM), was immobilized on sintered glass (SIRAN McKay et al., 1994; Phelps et al., 1990; Shields et al., carriers) and activated carbon. The inert open-pore struc-1994). The most commonly studied microorganisms are tures of the sintered glass and the strongly, TCE-ab-Methylosinus trichosporium OB3b (Brusseau et al., sorbing activated carbon provide a large surface area for

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