Kinetics of the simultaneous utilization of sugar mixtures by Escherichia coli in continuous culture.
AUTOR(ES)
Lendenmann, U
RESUMO
In natural environments heterotrophic microorganisms encounter complex mixtures of carbon sources, each of which is present at a concentration of a few micrograms per liter or even less. Under such conditions no significant growth would be expected if cells utilized only one of the available carbon compounds, as suggested by the principle of diauxic growth. Indeed, there is much evidence that microbial cells utilize many carbon compounds simultaneously. Whereas the kinetics of single-substrate and diauxic growth are well understood, little is known about how microbial growth rates depend on the concentrations of several simultaneously utilized carbon sources. In this study this question was answered for carbon-limited chemostat growth of Escherichia coli fed with mixtures of up to six sugars; the sugars used were glucose, galactose, maltose, ribose, arabinose, and fructose. Independent of the mixture composition and dilution rate tested, E. coli utilized all sugars simultaneously. Compared with growth with a single sugar at a particular growth rate, the steady-state concentrations were consistently lower during simultaneous utilization of mixtures of sugars. The steady-state concentrations of particular sugars depended approximately linearly on their contributions to the total carbon consumption rate of the culture. Our experimental data demonstrate that the simultaneous utilization of mixtures of carbon sources enables heterotrophic microbes to grow relatively fast even in the presence of low environmental substrate concentrations. We propose that the observed reductions in the steady-state concentrations of individual carbon sources during simultaneous utilization of mixtures of carbon sources by heterotrophic microorganisms reflect a general kinetic principle.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=167924Documentos Relacionados
- Temperature-dependent growth kinetics of Escherichia coli ML 30 in glucose-limited continuous culture.
- Acetate kinase production by Escherichia coli during steady-state and transient growth in continuous culture.
- Cellular levels, excretion, and synthesis rates of cyclic AMP in Escherichia coli grown in continuous culture.
- Effects of varying the carbon source limiting growth on yield and maintenance characteristics of Escherichia coli in continuous culture.
- Carbohydrate metabolism by Actinomyces viscosus growing in continuous culture.