Effect of dissolved oxygen regime on growth dynamics of Pseudomonas spp during benzene degradation

Abstract

We investigated the effect of different oxygen regimes on growth patterns of Pseudomonas spp. during benzene degradation in microcosm batch studies. Benzene degradation was induced by limiting oxygen available for microbial activity, which consists of three initial-dissolved oxygen (DO) levels of oxic, hypoxic, and anoxic conditions. Batch experiments were performed for cell growth and benzene degradation by inoculating three strains of Pseudomonas spp. (Pseudomonas aeruginosa, Pseudomonas fluorescens, Pseudomonas putida) in mineral salt medium containing aqueous benzene. Results showed that all strains were capable to grow and degrade benzene under all oxygen regimes but in a different manner. The highest cell growth of P. aeruginosa and P. fluorescens was achieved under oxic and anoxic condition, respectively, but there was no substantial difference on benzene degradation between the oxygen treatments with about 25% reduction for both strains. P. putida showed a facultative process for both cell growth and benzene degradation. This reveals that care should be taken in selection of microorganisms with regard to environmental studies since they exhibit different responses for given environmental conditions such as DO levels.

Speedy speciation in a bacterial microcosm: new species can arise as frequently as adaptations within a species

“…Recurrent evolution of a mat-forming ecotype occurred also in non-stirred microcosms of Pseudomonas evolution . We predict that in our system the non-mat ecotypes have diverged in other, yet unrecognized, ecological dimensions, perhaps by utilizing different chemical resources or by utilizing the more hypoxic, conic bottom of the tube (Mahendran et al, 2006).…”

Modeling the Differences in Biochemical Capabilities ofPseudomonasSpecies by Flux Balance Analysis: How Good Are Genome-Scale Metabolic Networks at Predicting the Differences?

“…The growth patterns of the three Pseudomonas species during benzene degradation have been previously investigated under different oxygen regimes, namely, oxic, hypoxic, and anoxic regimes [39]. All of the strains used in the experiment were capable of growing under all oxygen regimes but in a different manner.…”

Soil Clogging Genesis in Soil Treatment Units Used for Onsite Wastewater Reclamation: A Review

“…McKinley (2008) observed that alternating aerobic (4 mg/L dissolved oxygen for 8 hr) and anaerobic (0.8-1 mg/L dissolved oxygen for 16 hr) conditions stimulated concentrated biomass accumulation within the Organic carbon levels at the soil IS were 400-800% higher in soil exposed to aerobic/anaerobic conditions compared to sustained anaerobic conditions Krieg et al 1986 Oxygen stimulates EPS production Bayer et al 1990 EPS production by P. aeruginosa stimulated by oxygen Leitao and Sa-Correia 1993 Increased EPS production from P. aeruginosa under microaerophilic conditions Hassett 1996 EPS production by P. aeruginosa stimulated by oxygen Gamar-Nourani et al 1998 Microaerophilic conditions stimulated EPS over-production by bacteria Mathee et al 1999 EPS production by P. aeruginosa stimulated by oxygen Sabra et al 2002 Increased EPS production from P. aeruginosa under microaerophilic conditions Wyckoff et al 2002 Oxygen stimulates EPS production Akolkar and Lele 2004 Fermentative bacteria produced more EPS in a microaerophilic environment compared to anaerobic or aerobic conditions. Wilshusen et al 2004 Bacteria produced 250% more EPS under microaerophilic environment than anaerobic Mahendran et al 2006 EPS production by P. aeruginosa stimulated by oxygen media relative to strictly anaerobic conditions. This accumulation was confirmed visually and through measurements of pressure loss across the porous media.…”