Adaptive responses to static conditions in nutrient-rich cultures of luminous Ralstonia eutropha

Šimkus, Remigijus; Meškienė, Rita; Leth, Suzanne; Csöregi, Elisabeth

doi:10.1023/b:bile.0000021955.27361.4b

Cited by 4 publications

(2 citation statements)

References 10 publications

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“…In related studies it was shown that bioluminescence from the millilitre-scale air-exposed samples of lux gene fused bacteria (known as whole-cell biosensors (12,13)) becomes unstable when the population density is sufficiently high (~0.10 mg biomass/mL) (14)(15)(16)(17). This phenomenon was called oscillatory bioluminescence.…”

Section: Introductionmentioning

confidence: 99%

Metabolic self‐organization of bioluminescent Escherichia coli

Šimkus

Baronas

2011

Luminescence

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A possible reason for the complexity of the signals produced by bioluminescent biosensors might be self-organization of the cells. In order to verify this possibility, bioluminescence images of cultures of lux gene reporter Escherichia coli were recorded for several hours after being placed into 8-10 mm diameter cylindrical containers. It was found that luminous cells distribute near the three-phase contact line, forming irregular azimuthal waves. As we show, space-time plots of quasi-one-dimensional bioluminescence measured along the contact line can be simulated by reaction-diffusion-chemotaxis equations, in which the reaction term for the cells is a logistic (autocatalytic) growth function. It was found that the growth rate of the luminous cells (~0.02 s(-1)) is >100 times higher than the growth rate of E. coli. We provide an explanation for this result by assuming that E. coli exhibits considerable respiratory flexibility (the ability of oxygen-induced switching from one metabolic pathway to another). According to the simple two-state model presented here, the number of oxic (luminous) cells grows at the expense of anoxic (dark) cells, whereas the total number of (oxic and anoxic) cells remains unchanged. It is conjectured that the corresponding reaction-diffusion-chemotaxis model for bioluminescence pattern formation can be considered as a model for the energy-taxis and metabolic self-organization in the population of the metabolically flexible bacteria under hypoxic conditions.

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Section: Introductionmentioning

confidence: 99%

Metabolic self‐organization of bioluminescent Escherichia coli

Šimkus

Baronas

2011

Luminescence

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“…Alcaligenes eutrophus AE1308, a transconjugant of A. eutrophus CH34 and A. eutrophus JMP134 (former name of C. necator JMP134) have been successfully used to form active biofilm into membrane reactor for wastewater treatment (Diels et al, 1995). Other studies carried out in different environments showed that strains similar to C. necator JMP134 were able to form biofilms: Ralstonia eutropha (Steinle et al, 1998; Simkus et al, 2004), Ralstonia solanacaerum (Tans-Kersten et al, 2001; Kang et al, 2002), A. eutrophus (Mergeay et al, 1985; VanRoy et al, 1997), Alcaligenes denitrificans (Elvers et al, 1998), Alcaligenes xylosoxydans (Meade et al, 2001). We did not measure exactly the surface area and thickness of the biofilm.…”

Section: Discussionmentioning

confidence: 98%

Biofilm vs. Planktonic Lifestyle: Consequences for Pesticide 2,4-D Metabolism by Cupriavidus necator JMP134

et al. 2017

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The development of bacterial biofilms in natural environments may alter important functions, such as pollutant bioremediation by modifying both the degraders' physiology and/or interactions within the matrix. The present study focuses on the influence of biofilm formation on the metabolism of a pesticide, 2,4-dichlorophenoxyacetic acid (2,4-D), by Cupriavidus necator JMP134. Pure cultures were established in a liquid medium with 2,4-D as a sole carbon source with or without sand grains for 10 days. Bacterial numbers and 2,4-D concentrations in solution were followed by spectrophotometry, the respiration rate by gas chromatography and the surface colonization by electron microscopy. In addition, isotopic techniques coupled with Fatty Acid Methyl Ester (FAME) profiling were used to determine possible metabolic changes. After only 3 days, approximately 80% of the cells were attached to the sand grains and microscopy images showed that the porous medium was totally clogged by the development of a biofilm. After 10 days, there was 25% less 2,4-D in the solution in samples with sand than in control samples. This difference was due to (1) a higher (+8%) mineralization of 2,4-D by sessile bacteria and (2) a retention (15%) of 2,4-D in the biofilm matrix. Besides, the amount of carbohydrates, presumably constituting the biofilm polysaccharides, increased by 63%. Compound-specific isotope analysis revealed that the FAME isotopic signature was less affected by the biofilm lifestyle than was the FAME composition. These results suggest that sessile bacteria differ more in their anabolism than in their catabolism compared to their planktonic counterparts. This study stresses the importance of considering interactions between microorganisms and their habitat when studying pollutant dynamics in porous media.

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Bioluminescent monitoring of turbulent bioconvection

Šimkus¹

2006

Luminescence

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Under adjusted experimental conditions, open-to-air cultures of lux gene-engineered Ralstonia eutropha (wholecell biosensors of copper) exhibit bioconvection, which accounts for fluctuating bioluminescence. The power spectrum of bioluminescence intensity fluctuations recorded from a cylindrical sample 9 mm in diameter and approximately 10 mm in height is characterized by a dominant low-frequency oscillation (with a characteristic period of approximately 8-12 min), which is occasionally accompanied by a few weaker oscillations. The corresponding spectral peaks emerge on a high-noise background. The spectra of bioluminescence intensity fluctuations qualitatively resemble the spectra of temperature or fluid velocity fluctuations in an appropriate turbulent thermal convection system. It has been suggested that in a bioconvective system, like in thermal convection systems, the emergence of oscillation reflects the large-scale convective circulation that spans the height of the cylindrical cell. The velocity of large-scale bioconvective circulation was estimated to be 37-48 microm/s. The occasional emergence of weaker-than-dominant oscillations was explained through the coexistence and interaction of the large-scale circulation with, presumably, a gene-expression-related cyclic process (with a characteristic period of approximately 25-50 min).

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Adaptive responses to static conditions in nutrient-rich cultures of luminous Ralstonia eutropha

Cited by 4 publications

References 10 publications

Metabolic self‐organization of bioluminescent Escherichia coli

Metabolic self‐organization of bioluminescent Escherichia coli

Biofilm vs. Planktonic Lifestyle: Consequences for Pesticide 2,4-D Metabolism by Cupriavidus necator JMP134

Bioluminescent monitoring of turbulent bioconvection

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