Toluene degradation kinetics for planktonic and biofilm‐grown cells of Pseudomonas putida 54G

Abstract

Toluene degradation kinetics by biofilm and planktonic cells of Pseudomonas putida 54G were compared in this study. Batch degradation of 14 C toluene was used to evaluate kinetic parameters for planktonic cells. The kinetic parameters determined for toluene degradation were: specific growth rate, µ max = 10.08 ± 1.2/day; half-saturation constant, K S = 3.98 ± 1.28 mg/L; substrate inhibition constant, K I = 42.78 ± 3.87 mg/L. Biofilm cells, grown on ceramic rings in vapor phase bioreactors, were removed and suspended in batch cultures to calculate 14 C toluene degradation rates. Specific activities measured for planktonic and biofilm cells were similar based on toluene degrading cells and total biomass. Long-term toluene exposure reduced specific activities that were based on total biomass for both biofilm and planktonic cells. These results suggest that long-term toluene exposure caused a large portion of the biomass to become inactive, even though the biofilm was not substrate limited. Conversely, specific activities based on numbers of toluene-culturable cells were comparable for both biofilm and planktonically grown cultures. Planktonic cell kinetics are often used in bioreactor models to model substrate degradation and growth of bacteria in biofilms, a procedure we found to be appropriate for this organism. For superior bioreactor design, however, changes in cellular activity that occur during biofilm development should be investigated under conditions relevant to reactor operation before predictive models for bioreactor systems are developed.

Correlation of Biological Activity and Reactor Performance in Biofiltration of Toluene with the Fungus Paecilomyces variotii CBS115145

“…The reduction in microbial activity as a function of inlet substrate concentration in fixed-bed bioreactors was reported previously by Deront et al (6). Other authors have estimated specific microbial activity from enzymatic assays and from toluene uptake rates (15). Song and Kinney (22) on May 9, 2018 by guest http://aem.asm.org/ bacteria.…”

“…However, several au-thors (6,15,22) have correlated performance and metabolic measurements in bacterial biofilters.…”

Isolation and characterisation of fungi growing on volatile aromatic hydrocarbons as their sole carbon and energy source

“…Fungi were found to be comparable to bacteria in relation to the substrate affinity and toxicity for toluene. The apparent K m measured in fungal cell suspensions, as determined from the overall toluene oxidation (Table 4), fell into the range of reported Monod constants for toluene degradation by Pseudomonas species (0n4 to 43n3 µ ; Change et al 1993, Mirpuri et al 1997, Mars et al 1998. Furthermore, the 50 % IC values measured for fungi are similar to those reported for most aerobic bacteria, but remain well below the values for solvent-tolerant bacteria (Blum & Speece 1991, Weber, Schemen & Hartmans 1995, de Bont 1998.…”

“…Therefore, the specific growth rates of our fungal isolates are expected to be lower than the respiration rates given in Tables 2 and 3. From these results it is clear that the fungi grew on toluene with doubling times of at least 2-3 days in contrast to their bacterial counterparts, which exhibit doubling times of only 1-3 hours (Chang, Voice & Criddle 1993, Mirpuri, Jones & Bryers 1997, Mars et al 1998. The white colony forming strains Pseudeurotium sp.…”

Variation in Bacterial ATP Level and Proton Motive Force Due to Adhesion to a Solid Surface

“…The first reported observation of this effect was made in 1943, where it was found that bacterial activity increased in the presence of glass surfaces, particularly with low nutrient concentrations (54). Since this first study, researchers have examined how various materials, including glass and polymer surfaces (10, 11, 24-26, 40, 44, 47), silicone surfaces (52), ceramic surfaces (32), dialysis membranes (18), activated carbon (7), clays (43), sands (31,48), estuary particles (19), and ion exchange resins (46), affect the metabolic activity of attached bacteria.…”