Physiologic, morphologic and behavioral responses of perpetual cultures ofCaulobacter crescentus to carbon, nitrogen and phosphorus limitations

Felzenberg, E R; Yang, Guangying; Hagenzieker, J G; Poindexter, Jeanne S.

doi:10.1007/bf01574698

Cited by 11 publications

(7 citation statements)

References 50 publications

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“…We consider that the NNA-P was probably inorganic polyphosphate that is known to accumulate in some strains whenever P is not limiting (e.g. Felzenberg et al 1996). In support of this, the proportion of NNA-P increased at higher growth rates at the supply C:P of 373.…”

Section: Did the Bacterial Community Conform To The Grh?mentioning

confidence: 64%

Elemental stoichiometry of a heterotrophic bacterial community in a freshwater lake: implications for growth- and resource-dependent variations

Makino¹,

Cotner²

2004

Aquat. Microb. Ecol.

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The growth rate hypothesis (GRH) suggests that growth and elemental stoichiometry of organisms are coupled through variation in nucleic acid composition, specifically variation in ribosomal RNA. We examined these interactions in a bacterial community (<1 µm water) from the moderately productive Lake Owasso (Minnesota, USA). A mixed bacterial community was grown in chemostats with different supply carbon:phosphorus ratios (93, 373 and 933 by atoms) and dilution (= growth) rates (0.25, 0.5 and 0.7 h -1 ). We measured bacterial C, N, P, DNA and RNA content to determine resource-and growth-dependent variations in the elemental stoichiometry of bacterial biomass at the community level. In chemostats with high supply C:P ratios (≥ 373), biomass P increased proportionally to growth rate as a result of increased RNA content. High growth rates generated low biomass C:P and N:P ratios. At a low supply C:P (93:1), biomass C:P and N:P increased with increasing growth rate, even though RNA content increased, suggesting that non-nucleic acid P (presumably polyphosphate) was the dominant P-pool in this community and may have been more important in altering biomass stoichiometry at increasing growth rates. Therefore, the coupling of stoichiometry to growth predicted by the growth rate hypothesis was applicable only under P-limited conditions. These chemostat results revealed more complicated responses of bacterial C:N:P stoichiometry at a community level than in individual strains. The Lake Owasso bacterial community was more homeostatic in terms of biomass C:P and N:P stoichiometry than other bacterial communities described in the literature, and the degree of homeostasis for the Lake Owasso bacterial community was similar to that of single bacterial strains. However, few similar measurements have been made, and the degree of biomass C:N:P homeostasis may vary between systems and even within a system during different seasons.

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Section: Did the Bacterial Community Conform To The Grh?mentioning

confidence: 64%

Elemental stoichiometry of a heterotrophic bacterial community in a freshwater lake: implications for growth- and resource-dependent variations

Makino¹,

Cotner²

2004

Aquat. Microb. Ecol.

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“…The rate of phosphate uptake was higher in stalked cells than in swarmer cells when calculated per cell or per unit of protein, but the rates were similar between the two cell types when calculated as activity per cell surface area, including the surface area of the stalk (13). Stalk elongation may have additional roles in the environment.…”

Section: Discussionmentioning

confidence: 88%

“…Recent studies have demonstrated that the rate of phosphate uptake (per cell, unit dry weight, or protein) and the specific activity of alkaline phosphatase increased at higher carbon/phosphorus ratios (13). The rate of phosphate uptake was higher in stalked cells than in swarmer cells when calculated per cell or per unit of protein, but the rates were similar between the two cell types when calculated as activity per cell surface area, including the surface area of the stalk (13).…”

Section: Discussionmentioning

confidence: 99%

Regulation of Stalk Elongation by Phosphate in Caulobacter crescentus

et al. 2000

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In Caulobacter crescentus, stalk biosynthesis is regulated by cell cycle cues and by extracellular phosphate concentration. Phosphate-starved cells undergo dramatic stalk elongation to produce stalks as much as 30 times as long as those of cells growing in phosphate-rich medium. To identify genes involved in the control of stalk elongation, transposon mutants were isolated that exhibited a long-stalk phenotype irrespective of extracellular phosphate concentration. The disrupted genes were identified as homologues of the high-affinity phosphate transport genes pstSCAB of Escherichia coli. In E. coli, pst mutants have a constitutively expressed phosphate (Pho) regulon. To determine if stalk elongation is regulated by the Pho regulon, the Caulobacter phoB gene that encodes the transcriptional activator of the Pho regulon was cloned and mutated. While phoB was not required for stalk synthesis or for the cell cycle timing of stalk synthesis initiation, it was required for stalk elongation in response to phosphate starvation. Both pstS and phoB mutants were deficient in phosphate transport. When a phoB mutant was grown with limiting phosphate concentrations, stalks only increased in length by an average of 1.4-fold compared to the average 9-fold increase in stalk length of wild-type cells grown in the same medium. Thus, the phenotypes of phoB and pst mutants were opposite. phoB mutants were unable to elongate stalks during phosphate starvation, whereas pst mutants made long stalks in both high-and low-phosphate media. Analysis of double pst phoB mutants indicated that the long-stalk phenotype of pst mutants was dependent on phoB. In addition, analysis of a pstS-lacZ transcriptional fusion showed that pstS transcription is dependent on phoB. These results suggest that the signal transduction pathway that stimulates stalk elongation in response to phosphate starvation is mediated by the Pst proteins and the response regulator PhoB.

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“…The identification of two alkaline phosphatases in the stalk is consistent with one of the hypothesized functions of the stalk: phosphate uptake. Stalks elongate when phosphate is limiting, increasing the surface area available for phosphate uptake (Felzenberg et al , 1996). The presence of alkaline phosphatases would allow the uptake of organic phosphate by the stalk.…”

Section: Discussionmentioning

confidence: 99%

Proteomic analysis of the Caulobacter crescentus stalk indicates competence for nutrient uptake

Ireland¹,

Karty

Quardokus³

et al. 2002

Molecular Microbiology

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Summary Caulobacter crescentus , a Gram‐negative α ‐purple proteobacterium, is an oligotroph that lives in aquatic environments dilute in nutrients. This bacterium divides asymmetrically. Part of this asymmetric cell division involves the formation of a prosthecum at one pole, referred to as the stalk, which replaces the flagellum of the motile swarmer cell. Little is known about the synthesis or function of the stalk. The stalk is an extension of the cell membranes and peptidoglycan layer, and stalk elongation is stimulated by phosphate starvation. In this study, we have taken advantage of two‐dimensional gel (2D gel) electro‐phoresis as well as the fully sequenced genome of Caulobacter to study the proteome of the stalk. We modified a stalk‐shedding mutant strain of Caulobacter crescentus to increase the yield of stalk material shed and performed 2D gel electrophoresis of purified stalks and cellular fractions. Comparison of the stalk 2D gel with the 2D gels of cell membrane and soluble fractions showed that the stalk is mostly free of cytoplasmic proteins and has a profile very similar to that of the cell membrane. Of the 172 proteins on a stalk 2D gel, we report the identification of 64 spots, corresponding to 39 different proteins present in the stalk of Caulobacter. The identifications include several TonB‐dependent receptors, two OmpA family proteins, a dipeptidase, GlpQ, two alkaline phosphatases, 3‐phytase, a putative TolC protein and 11 proteins of unknown function. These identifications are consistent with the hypothesis that the stalk plays a role in nutrient uptake.

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Physiologic, morphologic and behavioral responses of perpetual cultures ofCaulobacter crescentus to carbon, nitrogen and phosphorus limitations

Cited by 11 publications

References 50 publications

Elemental stoichiometry of a heterotrophic bacterial community in a freshwater lake: implications for growth- and resource-dependent variations

Elemental stoichiometry of a heterotrophic bacterial community in a freshwater lake: implications for growth- and resource-dependent variations

Regulation of Stalk Elongation by Phosphate in Caulobacter crescentus

Proteomic analysis of the Caulobacter crescentus stalk indicates competence for nutrient uptake

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