Physiologische und morphologische Untersuchungen an Chlorobakterien

Mechsner, Kl.

doi:10.1007/bf00424849

Cited by 22 publications

(4 citation statements)

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“…It was shown by Muller"' that cultures of purple sulfur bacteria growing at the expense of acetate produce approximately 0.17 moles of C02 per mole of acetate metabolized. This value is slightly lower than the value predicted by equation (3), as would be expected if some of the C02 formed from acetate is subsequently fixed during the conversion of the primary reserve material to general cellular materials. In our experiments on the assimilation of acetate-C'4 by Chlorobium, we have made several determinations of the fraction of the total radioactivity present in C02 after the complete utilization of acetate.…”

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confidence: 54%

The Function of Acetate in Photosynthesis by Green Bacteria

Sadler

Stanier²

1960

Proc. Natl. Acad. Sci. U.S.A.

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Our present knowledge of the physiology and biochemistry of green sulfur bacteria (genus Chlorobium) is largely based on the studies of van Niel' and of Larsen.2 Their work showed that the members of this genus are strictly anaerobic, obligate photolithotrophs, which perform a typical bacterial photosynthesis using reduced inorganic sulfur compounds as electron donors. The physiology of these photosynthetic bacteria is accordingly similar to that of the purple sulfur bacteria, with one significant exception: all members of the latter group so far studied in pure culture can also use a variety of simple organic substrates for photosynthesis in the absence of a reduced inorganic sulfur compound. The possible participation of organic compounds in the photometabolism of green bacteria was examined in detail by Larsen,2 using Chlorobium thiosulfatophilum. He found that none of the simple organic compounds commonly used as substrates for photosynthesis by purple sulfur bacteria could support the photosynthetic growth of C. thiosulfatophilum. However, manometric experiments suggested that resting cells could bring about a slow and limited transformation of organic acids anaerobically in the light. Only with propionate was a rapid metabolism observed. More detailed study showed that C. thiosulfatophilum performs a unique photosynthetic reaction with this substrate, grossly expressed by the equation:CH3CH2COOH + CO2 light HOOCCH2CH9COOH.(1)A large part of the propionic acid metabolized is excreted into the medium as succinic acid. The physiological function of this reaction is obscure. Larsen2 commented: "it can be safely concluded that the formation of succinic acid can hardly be considered as an important stage in the normal assimilatory process." However, the existence of the reaction revealed one very important fact: the failure of green bacteria to utilize organic compounds for growth cannot be attributed to the failure of such compounds to enter the cell.Recently, Mechsner3 has reported that a new species of Chlorobium, C. chiorochromatii, can grow well photosynthetically at the expense of peptone and malate. He confirmed, however, that the two species studied by Larsen, viz. C. limicola and C. thiosulfatophilum, are unable to utilize organic compounds for growth. This paper reports certain new observations on the utilization of organic substrates by C. limicola.Materials and Methods-Organisms and culture conditions: Several strains of C. limicola were isolated from local mud samples using the procedures described by Larsen2 for enrichment and purification. Larsen's mineral medium,"z which contains 0.024 M NaHCO3 and 0.0042 M Na2S, was used routinely for cultivation. In this medium, sulfide is the growth-limiting nutrient, as shown by preliminary experiments in which the sulfide content was varied, other components being kept constant. There is strict proportionality between cell yield and sulfide concentration 1328

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confidence: 54%

The Function of Acetate in Photosynthesis by Green Bacteria

Sadler

Stanier²

1960

Proc. Natl. Acad. Sci. U.S.A.

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“…C Flagella stained with crystal violet. Highly refractile appearance of whole consortia is caused by the stain (bar 10 µm) Anagnostidis and Overbeck (1966), Baker et al (1985), Blakar (1979), Caldwell and Tiedje (1974a, b), Croome and Tyler (1984), Dubinina and Kuznetsov (1976), Eichler and Pfennig (1990), Gasol et al (1995), Gorlenko (1988), Gorlenko and Chebotarev (1981), Gorlenko and Kusnetsov (1971), Gorlenko and Kusnezow (1972), Gorlenko and Lokk (1979), King and Tyler (1982), Mechsner (1957), Overbeck (1974), Overmann (Grünen-plan, unpublished), Overmann and Tilzer (1989), Parkin and Brock (1980), Skuja (1957), Utermöhl (1923) colored counterparts (0.2-10 m; data from the references cited in Table 2). Due to the absorption characteristics of lake water, the underwater light spectrum progressively narrows with depth.…”

Section: Discussionmentioning

confidence: 95%

The ecological niche of the consortium " Pelochromatium roseum "

Overmann

Tuschak

Sass

et al. 1998

Archives of Microbiology

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A dense accumulation of the phototrophic consortium "Pelochromatium roseum" in a small, eutrophic, freshwater lake (Dagowsee, Brandenburg, Germany) was investigated. Within the chemocline, the number of epibionts of the consortia represented up to 19% of the total number of bacteria. Per "P. roseum" a mean value of 20 epibionts was determined. Similar to other aquatic habitats, consortia in the Dagowsee were found only at low light intensities (< 7 &mgr;mol quanta m-2 s-1) and low sulfide concentrations (0-100 &mgr;M). In dialysis cultures of "P. roseum", bacterial cells remained in a stable association only when incubated at light intensities between 5 and 10 &mgr;mol quanta m-2 s-1. Intact consortia from natural samples had a buoyant density of 1046.8 kg m-3, which was much higher than that of ambient chemocline water (995.8 kg m-3). Under environmental conditions and without motility, this density difference would result in rapid sedimentation of consortia toward the lake bottom. Our results indicate that (1) consortia are adapted to a very narrow regime of light intensities and sulfide concentrations, (2) motility and tactic responses must be of ecological significance for the colonization of the free water column of lakes, and (3) phototrophic growth of consortia can be explained only by a cycling of sulfur species in the chemocline, possibly within the consortia themselves.

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“…Until recently, all attempts to enrich phototrophic consortia have been unsuccessful and none of the consortium members are in culture. The isolation of a green sulfur bacterium from ‘ C. aggregatum ’ was reported by Mechsner [53], but unfortunately the strain was lost before detailed physiological studies could be made. ‘ C. aggregatum ’ from a eutrophic freshwater lake exhibited a pronounced chemotaxis toward 2‐oxoglutarate, and using mineral media supplemented with this carbon substrate, a stable enrichment culture could be established for the first time since the discovery of phototrophic consortia [54].…”

Section: Phototrophic Consortiamentioning

confidence: 99%

Microbial interactions involving sulfur bacteria: implications for the ecology and evolution of bacterial communities

2000

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A major goal of microbial ecology is the identification and characterization of those microorganisms which govern transformations in natural ecosystems. This review summarizes our present knowledge of microbial interactions in the natural sulfur cycle. Central to the discussion is the recent progress made in understanding the co-occurrence in natural ecosystems of sulfur bacteria with contrasting nutritional requirements and of the spatially very close associations of bacteria, the so-called phototrophic consortia (e.g. 'Chlorochromatium aggregatum' or 'Pelochromatium roseum'). In a similar way, microbial interactions may also be significant during microbial transformations other than the sulfur cycle in natural ecosystems, and could also explain the low culturability of bacteria from natural samples.

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Physiologische und morphologische Untersuchungen an Chlorobakterien

Cited by 22 publications

References 33 publications

The Function of Acetate in Photosynthesis by Green Bacteria

The Function of Acetate in Photosynthesis by Green Bacteria

The ecological niche of the consortium " Pelochromatium roseum "

Microbial interactions involving sulfur bacteria: implications for the ecology and evolution of bacterial communities

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