Growth and xanthan production of Xanthomonas campestris depending on the N-source concentration

Prell, A.; Lasík, J.; Koníčék, J.; Sobotka, M.; Sýs, J.

doi:10.1007/bf00369559

Cited by 5 publications

(3 citation statements)

References 11 publications

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“…The bacterium X. campestris produces xanthan polymer at a rate as high as 10 4 polymer coils per cell per second (as estimated from the data given in Refs. [18,19]). Assuming a ratio R 1 /R 2 = 10 − 100, corresponding to a polymer gyration radius of 10-100 nm, hence to a value of k c R 2 2 /D 1 ∼ 1 − 100, and referring to Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Although our model is designed to be generic, our work is inspired by the observation that many bacterial cells secrete extracellular polysaccharides [16,17], in some cases in large quantities (for example the bacterium Xanthomonas campestris can produce xanthan polymer at a rate as high as 10 4 polymer molecules per cell per second [18,19]).…”

Section: Introductionmentioning

confidence: 99%

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Non-equilibrium dynamics of an active colloidal “chucker”

Valeriani

Allen

Marenduzzo

2010

The Journal of Chemical Physics

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We report Monte Carlo simulations of the dynamics of a "chucker": a colloidal particle which emits smaller solute particles from its surface, isotropically and at a constant rate k c . We find that the diffusion constant of the chucker increases for small k c , as recently predicted theoretically. At large k c the chucker diffuses more slowly due to crowding effects. We compare our simulation results to those of a "point particle" Langevin dynamics scheme in which the solute concentration field is calculated analytically, and in which hydrodynamic effects arising from colloid-solvent surface interactions can be accounted for in a coarse-grained way. By simulating the dragging of a chucker, we obtain an estimate of its apparent mobility coefficient which violates the fluctuation-dissipation theorem. We also characterise the probability density profile for a chucker which sediments onto a surface which either repels or absorbs the solute particles, and find that the steady state distributions are very different in the two cases. Our simulations are inspired by the biological example of exopolysaccharide-producing bacteria, as well as by recent experimental, simulation and theoretical work on phoretic colloidal "swimmers".

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Non-equilibrium dynamics of an active colloidal “chucker”

Valeriani

Allen

Marenduzzo

2010

The Journal of Chemical Physics

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“…Many studies have focused on the optimization of culture conditions for the production of polysaccharides. Some strains synthesized polysaccharides at a maximum rate during exponential growth and little more polymer was formed after growth ceased (Mian et al, 1978;Prell et al, 1995). In contrast, many strains produce polysaccharides under nutrient-limited conditions.…”

Section: Introductionmentioning

confidence: 99%

Higher intracellular levels of uridinemonophosphate under nitrogen-limited conditions enhance metabolic flux of curdlan synthesis inAgrobacterium Species

Kim

Lee

et al. 1999

Biotechnol. Bioeng.

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Changes of intracellular nucleotide levels and their stimulatory effects on curdlan synthesis in Agrobacterium species were investigated under different culture conditions. Under nitrogen‐limited conditions where curdlan synthesis was stimulated, intracellular levels of UMP were as high as 87 and those of AMP were 78 nmol/mg of cellular protein, while those under nitrogen‐sufficient conditions were lower than 45 nmol/mg‐protein. The levels of other nucleotides such as UDP, UTP, UDP‐glucose, ADP, ATP, and ADP‐glucose were lower than 30 nmol/mg‐protein under both nitrogen‐limited and sufficient conditions. The time profiles of curdlan synthesis and cellular nucleotide levels showed that curdlan synthesis had a positive relationship with intracellular levels of UMP and AMP. After the ammonium concentration in the medium fell below 0.1 g/L, intracellular levels of UMP and AMP increased, followed by curdlan synthesis. However, no significant changes in the specific activities of UMP kinase, UDP kinase, and UDP‐glucose pyrophosphorylase were observed during cultivation. In vitro enzyme reactions for the synthesis of UDP‐glucose, which serve as a precursor for curdlan synthesis, demonstrated that the synthesis of UDP‐glucose increased with the increase of UMP concentration. In contrast, AMP had no effect on UDP‐glucose synthesis at all. Addition of UMP in the medium increased the curdlan synthesis, whereas curdlan synthesis was inhibited in the presence of AMP. From these results, we concluded that only the higher intracellular UMP levels caused by nitrogen limitation in the medium enhance the metabolic flux of curdlan synthesis by promoting cellular UDP‐glucose synthesis. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 62: 317–323, 1999.

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