Physiology and tactic response of the phototrophic consortium " Chlorochromatium aggregatum "

Fröstl, Jürgen M.; Overmann, Jörg

doi:10.1007/s002030050552

Cited by 63 publications

(77 citation statements)

References 14 publications

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“…These two responses may bias the swimming pattern of R. sphaeroides RK1 toward its most favorable light climate for photosynthesis, while simultaneously allowing it to avoid radiation damage. This pattern of opposite responses, as a function of either the color or the intensity of the actinic illumination, is often seen in phototrophic prokaryotes and algae (4,8,13,15,21).…”

Section: Discussionmentioning

confidence: 91%

Color-Sensitive Motility and Methanol Release Responses in Rhodobacter sphaeroides

2000

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Blue-light-induced repellent and demethylation responses, characteristic of behavioral adaptation, were observed in Rhodobacter sphaeroides. They were analyzed by computer-assisted motion analysis and through the release of volatile tritiated compounds from [methyl-3 H]methionine-labeled cells, respectively. Increases in the stop frequency and the rate of methanol release were induced by exposure of cells to repellent light signals, such as an increase in blue-and a decrease in infrared-light intensity. At a of >500 nm the amplitude of the methanol release response followed the absorbance spectrum of the photosynthetic pigments, suggesting that they function as photosensors for this response. In contrast to the previously reported motility response to a decrease in infrared light, the blue-light response reported here does not depend on the number of photosynthetic pigments per cell, suggesting that it is mediated by a separate sensor. Therefore, color discrimination in taxis responses in R. sphaeroides involves two photosensing systems: the photosynthetic pigments and an additional photosensor, responding to blue light. The signal generated by the former system could result in the migration of cells to a light climate beneficial for photosynthesis, while the blue-light system could allow cells to avoid too-high intensities of (harmful) blue light.Changes in the environmental light climate induce behavioral responses in photosynthetic purple bacteria, which allow them to migrate towards an environment beneficial for photosynthesis. Reports on photosynthetic bacteria that accumulate in infrared light are among the classics of microbiology (2, 3). In more recent years, more-complex behavioral responses of these organisms towards light have been reported. Free-swimming Ectothiorhodospira halophila cells, in addition, show a repellent response, with a maximal relative increase in the flagellar reversal frequency at 450 nm (20). A colony of Rhodospirillum centenum is repelled by intense green light (550 to 600 nm) and is attracted by red or infrared light that is absorbed by the photosynthetic pigments (15). Light-induced motility responses have also been analyzed in Rhodobacter sphaeroides WS8-N (1). This bacterium responds to a step-down in yellow-green light (530 to 600 nm), and infrared light in a background of red monitoring light (650 Ϯ 10 nm), by an increase in its stop or reorientation frequency, with adaptation taking approximately 2 min. The photosynthetic apparatus is the photosensor for this response (6).Stimulus-induced turnover of methylated carboxyl groups of methyl-accepting transducer proteins is a common feature of prokaryotic taxis-signaling pathways. Nevertheless, previous methanol release assays with intact R. sphaeroides cells have not revealed changes in methanol release upon the addition or removal of chemoeffectors (19). The recent finding of chemotaxis operons encoding MCP homologues, methyltransferases and -esterases, however, supports the involvement of a methylation-dependent adaptation p...

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Section: Discussionmentioning

confidence: 91%

Color-Sensitive Motility and Methanol Release Responses in Rhodobacter sphaeroides

2000

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“…This and similar consortia involving photosynthetic sulfur bacteria are highly successful, and occur worldwide in ponds that contain a lower H 2 S-rich layer [42]. It has been questioned whether H 2 S is transferred directly from species to species [43], but since the outer bacteria are obligate H 2 S consumers, sulfide oxidation is certainly involved.…”

Section: Methanogenic Syntrophy (Fig 5)mentioning

confidence: 99%

Metabolic integration during the evolutionary origin of mitochondria

Searcy

2003

Cell Res

115

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Although mitochondria provide eukaryotic cells with certain metabolic advantages, in other ways they may be disadvantageous. For example, mitochondria produce reactive oxygen species that damage both nucleocytoplasm and mitochondria, resulting in mutations, diseases, and aging. The relationship of mitochondria to the cytoplasm is best understood in the context of evolutionary history. Although it is clear that mitochondria evolved from symbiotic bacteria, the exact nature of the initial symbiosis is a matter of continuing debate. The exchange of nutrients between host and symbiont may have differed from that between the cytoplasm and mitochondria in modern cells. Speculations about the initial relationships include the following.(1) The pre-mitochondrion may have been an invasive, parasitic bacterium. The host did not benefit. (2) The relationship was a nutritional syntrophy based upon transfer of organic acids from host to symbiont. (3) The relationship was a syntrophy based upon H2 transfer from symbiont to host, where the host was a methanogen. (4) There was a syntrophy based upon reciprocal exchange of sulfur compounds. The last conjecture receives support from our detection in eukaryotic cells of substantial H2S-oxidizing activity in mitochondria, and sulfur-reducing activity in the cytoplasm.

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“…Based on the discovery of interspecies electron transfer through a sulfur cycle between phototrophs and chemotrophs in the undefined coculture 'Chloropseudomonas ethylica' (Biebl & Pfennig 1978), it was assumed that also in these consortia electron transfer proceeds through sulfur compounds, but this assumption could never be verified because no cultures of these consortia were available. Fröstl & Overmann (1998) have recently tackled this diffi-cult issue again and obtained highly enriched cultures of 'Chlorochromatium aggregatum' through enrichment based on skillful chemotaxis studies. It turned out that the consortium can be enriched with 2-oxoglutarate to which it is chemotactically attracted (Fröstl & Overmann 1998).…”

Section: Phototrophic Consortiamentioning

confidence: 99%

“…Fröstl & Overmann (1998) have recently tackled this diffi-cult issue again and obtained highly enriched cultures of 'Chlorochromatium aggregatum' through enrichment based on skillful chemotaxis studies. It turned out that the consortium can be enriched with 2-oxoglutarate to which it is chemotactically attracted (Fröstl & Overmann 1998). 16S rRNA probing revealed that the chemotrophic central bacterium in these consortia belongs to the β-proteobacteria and is highly unlikely to reduce sulfur compounds (Fröstl & Overmann 2000).…”

Section: Phototrophic Consortiamentioning

confidence: 99%

Untitled

Schink

2002

Antonie Van Leeuwenhoek

259

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After several decades of microbiological research has focused on pure cultures, synergistic effects between different types of microorganisms find increasing interest. Interspecies interactions between prokaryotic cells have been studied into depth mainly with respect to syntrophic cooperations involved in methanogenic degradation of electron-rich substrates such as fatty acids, alcohols, and aromatics. Partners involved in these processes have to run their metabolism at minimal energy increments, with only fractions of an ATP unit synthesized per substrate molecule metabolized, and their cooperation is intensified by close proximity of the partner cells. New examples of such syntrophic activities are anaerobic methane oxidation by presumably methanogenic and sulfate-reducing prokaryotes, and microbially mediated pyrite formation. Syntrophic relationships have also been discovered to be involved in the anaerobic metabolization of amino acids and sugars where energetical restrictions do not necessarily force the partner organisms into strict interdependencies. The most highly developed cooperative systems among prokaryotic cells appear to be the structurally organized phototrophic consortia of the Chlorochromatium and Pelochromatium type in which phototrophic and chemotrophic bacteria not only exchange metabolites but also interact at the level of growth coordination and tactic behaviour.

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Physiology and tactic response of the phototrophic consortium " Chlorochromatium aggregatum "

Cited by 63 publications

References 14 publications

Color-Sensitive Motility and Methanol Release Responses in Rhodobacter sphaeroides

Color-Sensitive Motility and Methanol Release Responses in Rhodobacter sphaeroides

Metabolic integration during the evolutionary origin of mitochondria

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