Cellular reporoduction and extracellular polymer formation by Pseudomonas aeruginosa in continuous culture

Abstract

The kinetics of cellular reproduction and the rate and extent of synthesis of extracellular polymeric substances (EPS) were investigated for P. aeruginosa growing in glucose-limited chemostats. mu(max) and K(s) estimates of 0.4 h(-1) and 2 mg glucose C/L, respectively, at 25 degrees C were obtained for this bacterium. The extent of EPS formation was inversely related to the growth rate of P. aeruginosa. The rate of EPS formation had both growth- and non-growth-associated components. The growth-associated polymer formation rate coefficient (k) was 0.3 mg polymer C/mg cellular C and the non-growth-associated polymer formation rate coefficient (k') was 0.04 mg polymer C/mg cellular C/h. The values for k and k' must be regarded as provisional since the product formation data were quite variable at low dilution rates. Estimates of the cellular (Y(x/s)) and polymer (Y(p/s)) yield coefficients were 0.3 mg cellular C/mg glucose C and 0.6 mg polymer C/mg glucose C, respectively. Most of the non-growth-associated consumption of glucose detected was due to exopolymer formation.

Microbial competition in porous environments can select against rapid biofilm growth

“…However, previous experiments have shown that faster-growing biofilms are more susceptible to flow-induced detachment (62)(63)(64)(65). This dependency may occur because fastgrowing genotypes invest less in secretions of exopolymeric substances that glue cells together (63) or because rapidly growing genotypes form biofilms with more fragile morphologies, rendering them more susceptible to detachment (55,66). To model how covariance between growth and detachment influences bacterial competition, we extended our model using the parameterization of Speitel and DiGiano (62), who empirically quantified this coupling in porous environments using radiolabeled carbon sources.…”

Specific ATP and specific oxygen uptake rate in immobilized cell aggregates: Experimental results and theoretical analysis using a structured model of immobilized cell growth

“…They may produce extracellular polymers (Characklis, 1973(Characklis, , 1981Characklis and Cooksey, 1983;Daniels, 1980;Robinson et al, 1984) which are usually lumped together with cells in dry biomass measurements, resulting in overestimation of the activity of immobilized biomass. In addition, cell location in the biofilm can affect its quality and activity, since profiles of environmental conditions such as substrate concentration often exist.…”

Trace metal mobilization in soil by bacterial polymers.

“…The amount of polymer observed decreased as Oc increased, indicating either reduced exopolymer production, increased biodegradation of polymer, or increased adsorption of polymer onto suspended solids (32). In a pure culture of Pseudomonas aeruginosa under conditions of carbon limitation, Robinson et al observed that extracellular polymer concentration increased with decreasing dilution rates (increasing EO) despite constant or decreasing cell populations (33). However, Mian et al found that both cell concentration and polymer concentration of P. aeruginosa were independent of dilution rate under conditions of nitrogen limitation (20).…”