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Theodor Wilhelm Engelmann (1843-1909), who had a creative life in music, muscle physiology, and microbiology, developed a sensitive method for tracing the photosynthetic oxygen production of unicellular plants by means of bacterial aerotaxis (chemotaxis). He discovered the absorption spectrum of bacteriopurpurin (bacteriochlorophyll a) and the scotophobic response, photokinesis, and photosynthesis of purple bacteria.

Following the discovery of photosynthetic bacteria in the nineteenth century, technical developments of the 1950s led to their use in membrane biogenesis studies. These investigations had their origins in the isolation of subcellular particles designated as ‘chromatophores’ by Roger Stanier and colleagues, which were shown to be photosynthetically competent by Albert Frenkel, and to originate from the intracytoplasmic membrane (ICM) continuum observed in electron micrographs. These ultrastrucutral studies by the G. Drews group, Germaine Cohen-Bazire and others also suggested that the ICM originates by invagination of the cytoplasmic membrane, as later established in the biochemical and biophysical work of the R. Niederman and Drews groups. Through a combination of genetic approaches, first introduced in the early 1980s by Barry Marrs, and the atomic resolution structures determined for light-harvesting antennae and reaction centers, a detailed understanding is emerging of mechanisms regulating their levels in the membrane and the roles played by specific protein domains and additional factors in their assembly and supramolecular organization. Prospects for additional progress during the twenty-first century include further elucidation of molecular aspects of the assembly process and the application of newer spectroscopic probes to photosynthetic unit formation.

We show in this paper that a complex constituted by phospholipids and LHI and LHII alpha polypeptides was inserted in a heavy membrane fraction in a nonextractable form, indicating a transmembrane localization. The best accepting membranes originated from aerobically grown cells. Addition of ATP during the insertion inhibited this reaction 25 to 30% in heavy membranes isolated from aerobically grown cells (HMaer) and a higher inhibition (60 to 65%) was detected when using heavy membranes isolated from photosynthetically grown cells (HMpho). Purification by gel filtration of a crude Na2CO3 extract yielded three phosphate-labeled fractions. Two of them contained protein and phospholipids in a stable association. However, only fractions containing phosphatidylethanolamine were shown to be reconstituted. The third radioactive fraction contained labeled ATP and protein, but no phospholipids and could not be reassociated to the heavy membranes of any origin. A model for the insertion of the LH polypeptides is presented in which the recently synthesized polypeptides are phosphorylated and become associated to anionic phospholipids. The interaction of this complex to the membrane spontaneously leads to stable insertion.

Membranes of Rhodobacter capsulatus strain U43 (pTX35) showed qualitatively very similar phosphorylation patterns under in vitro and in vivo conditions. In vitro, it was irrelevant whether the phosphate source was orthophosphate or ATP. Inhibitors of electron transport did not inhibit light-harvesting complex I (LHIα) (B870) polypeptide phosphorylation, except for o-phenanthroline, which was strongly inhibitory. Redox conditions regulated the amount of protein phosphorylated; external redox potentials between +200 and +300 mV promoted the reaction. Phosphorylation was inhibited by uncouplers such as carbonyl cyanide m-chlorophenyl hydrazone and nigericin plus valinomycin plus potassium ions. Inhibitors of the H+-ATPase were also inhibitory when the phosphate source was [32P]Pi or [γ-32P]ATP. From these results, it was concluded that an operative reaction center, a coupled membrane, and external redox potentials higher than +200 mV are required for optimum LHIα phosphorylation. We also demonstrated that phosphorylation of LHIα polypeptide occurs before insertion into the membrane and that phosphate is preferentially incorporated into specific domains within the cytoplasmic membrane. Intracytoplasmic membranes, identified here as light membranes, were found to contain a dephosphorylated LHIα polypeptide.

Labelling of Rhodobacter capsulatus cells with (32P)Pi in a phototrophic culture results in phosphorylation of a membrane-bound polypeptide identified as the α subunit of the LHI antenna complex of the photosynthetic apparatus. Phosphorylation of the same polypeptide was also observed by incubation of chromatophores with (32P)ATP or under conditions of photophosphorylation with ADP and (32P)Pi. The identity of the phosphorylated LHI-α subunit was demonstrated by N-terminal protein sequencing of the phosphorylated polypeptide and by failure of labelling in LHI-defective mutants. Pre-aeration of the samples or addition of the oxidant potassium ferrcyanide stimulated the kinase activity whereas the presence of soluble cytoplasmic proteins impaired phosphorylation in an in vitro assay. No effect resulted from addition of reductants to the assay medium. The results indicate the presence of a membrane-bound protein kinase in R. capsulatus that phosphorylates the α subunit of the LHI antenna complex under redox control.

The promoter of the Rhodobacter capsulatus hemA gene, coding for the enzyme δ-aminolevulinic acid synthase (ALAS), was identified by trans-complementation of a δ-aminolevulinic acid (ALA)-dependent mutant and found to be located within a 170 bp region proximal to the hemA gene. The activity of the hemA promoter was demonstrated by lacZ fusion and in vitro transcription-translation. An open reading frame (ORFX) was found downstream of hemA. The activity of the hemA promoter, but not that of the ORFX promoter, increased when oxygen tension was lowered in the culture. Deletions upstream of the hemA promoter region did not affect ALAS activity and formation of pigment-protein complexes in R. capsulatus.

Cells of Rhodobacter capsulatus wild-type strains (37b4, B 10) and mutant strains, lacking lightharvesting (LH) complex II (B800–850) and defective in formation of LH I (B870) complex [U 43 (pTXB 87), U43 (pTXA6-10)] were grown photosynthetically at high and low light intensities in a turbidostate. The mutant strain U43 (pTXA6-10), lacking any LH system, was able to grow at high and low light intensities with doubling times of 4.6 and 9.8 h, respectively. In this mutant the concentration of photochemical reaction centers (RC) per cell and per membrane protein was several times higher than in wild type cells, but the bacteriochlorophyll content, the size of the photosynthetic unit and the rate of photophosphorylation were lower than in wild type cells. Reversible bleaching of reaction center and photophosphorylation were measured under different excitation light intensities. The charge recombination in the RC between the primary donor and QB was very slow in the mutant strains. Two membrane fractions differing in absorption spectra and light saturation behaviour of reversible bleaching and photophosphorylation were isolated from the mutant strains. The experimental data indicate that photosynthetic units of different composition and/or organization are present in the mutant cells.

The obligate aerobic bacteria Roseococcus thiosulfatophilus RB3 and Erythromicrobium ramosum E5 contain numerous polar carotenoids. The major carotenoid of the strain RB3 was the C30 carotene-dioate (4,4′-diapocarotene-4,4′-dioate) and the respective diglycosyl ester which have never been isolated before from a bacteriochlorophyll containing bacterium. Strain E5 contains the very polar erythroxanthin sulphate. The major carotenoid bound to reaction center and light-harvesting complexes is bacteriorubixanthinal. Most of the carotenoids of both strains are not bound to the pigment-protein complexes of the photosynthetic apparatus but to the envelope fraction (cytoplasmic membrane and cell wall).

The photosynthetic apparatus of Rhodopseudomonas palustris contains, in addition to reaction center bacteriochlorophyll (Bchl) two spectral forms of light harvesting (LH) Bchl, i.e. LH Bchl I, characterized by an infrared absorption maximum at 880 nm (890 nm at 77 degrees K) and LH Bchl II absorbing at 805 and 855 nm (805 and 870 nm at 77 degrees K). LH Bchl I seems to be associated with a single protein species of an apparent mol. wt. of 13 000 whereas LH Bchl II is apparently associated with two proteins of mol. wts. of 9000 and 11 000. Cells in anaerobic cultures adapt to changes of light intensity 1. by variation of the size of the photosynthetic unit, i.e. the molar ratio of LH Bchl II to reaction center Bchl, 2. by variation of the number of photosynthetic units per unit of membrane area, 3. by regulation of the size of the intracytoplasmic membrane system. During adaptation of changes of oxygen partial pressure cells are able to synthesize reaction center Bchl, LH Bchl and intracytoplasmic membranes at different rates. The synthesis of reaction center Bchl and LH Bchl I are, however, coordinated with each other, while the synthesis of LH Bchl II and reaction center Bchl proceed independently.

Aerobically in the dark grown cultures of Rhodopseudomonas capsulata were shifted to low oxygen partial pressure for 30 min and afterwards to phototrophic conditions (anaerobic, light). During 210 min of adaptation to a phototrophic mode of life the bacteriochlorophyll (BChl) concentration increased 53-fold (doubling time 40 min) and the carotenoid content six fold. Growth was delayed. The light membrane fraction from chemotrophic and induced phototrophic cells contained low concentrations of small photosynthetic units (reaction center+light harvesting BChl B870), and low respiratory activities, especially of succinatecytochrome c oxidase. The heavy membrane fraction, i.e. the intracytoplasmic chromatophore fraction, increased during adaptation approximately 9-fold in surface area per cell, 42-fold in BChl content, 7-fold in reaction center content and 6-fold in the size of the photosynthetic unit. Phospholipid and fatty acid content and patterns changed slightly during adaptation.

Lipopolysaccharides have been isolated from eight strains of the unicellular cyanobacterium Synechococcus. Fucose, mannose, galactose, glucose and glucosamine were found in all of the lipopolysaccharides investigated. Additionally, strain-specific sugars are present and permit the chemotyping of lipopolysaccharide. Chemotype I, comprising three strains with a high G+C content of DNA (71-66 mol%), is characterized by a high rhamnose portion and by 3,6-dideoxy-d-arabino-hexose (tyvelose). Chemotype III, represented by three strains with a low G+C content of DNA (55-48 mol%), contains a mannose-polymer with small amounts of 3-O-methyl-mannose, 4-O-methyl-mannose, 2-keto-3-deoxyoctonate and mannosamine. Lipopolysaccharides of the two strains of chemotype II contain 2,3,4-tri-O-methyl-arabinose. Lipid A is difficult to split off from the polysaccharide moiety, but is present in all lipopolysaccharides from the Synechococcus strains. The presence of Lipid A is supported by the finding of β-hydroxy fatty acids, predominantly β-hydroxypalmitic acid. The distribution of branched β-hydroxy fatty acids, detected in small amounts, parallels chemotyping of lipopolysaccharide based on the sugar composition. The phosphorus content of the lipopolysaccharides is low. The pyrogenicity of lipopolysaccharides from two strains is low. Synechococcus lipopolysaccharides have little reactivity in antisera raised in rabbits against homologous cells. As far as tested they do not migrate in immunoelectrophoresis. This confirms the neutral character or low negative charge of Synechococcus lipopolysaccharides.

By means of sucrose density centrifugation three membrane fractions, named “light, medium and heavy” have been isolated from cells of Rhodopseudomonas capsulata strain 37b4, adapting from chemotrophic to phototrophic growth conditions. Succinate dehydrogenase activity of aerobically grown cells was mainly confined to the heavy (chromatophore) fraction. Upon changing to phototrophic conditions the activity of the succinate dehydrogenase increased in the medium and light fraction. All fractions contain bacteriochlorophyll. NADH dehydrogenase of chemotrophically grown cells was enriched in the light and medium fraction but is increased in the heavy fraction under phototrophic growth conditions. The capacity of photophosphorylation is high in the light and heavy fraction. The results indicate a differentially incorporation of functional subunits into specific parts of the membrane system during membrane differentiation.

The O-antigen (lipopolysaccharide) of Anacystis nidulans, strain KM, has been isolated from whole cells and from cell wall preparations by phenolwater extraction. The polysaccharide moiety consists of a D-mannose polymer accompanied by smaller amounts of 3- and 4-O-methyl-D-mannoses, D-galactose, D-glucose, L-fucose, D-glucosamine, mannosamine and 2-keto-3-deoxyoctonate. Aldoheptoses are lacking. The degraded polysaccharide is split from lipid A by acid hydrolysis (10% acetic acid, 100°C, 3 h) whereby 2-keto-3-deoxyoctonate is released in small amounts. Degraded polysaccharide forms only one major fraction by Sephadex G-50 gel-filtration. This fraction includes all the sugars mentioned above except L-fucose, which is released during the acetic acid degradation. Periodate studies and methylation analysis revealed that the poly-mannose chain consists of about 75% 1→3 linked and of 25% 1→4 linked D-mannose units. Lipid A of A. nidulans is phosphate-free. The main fatty acid, β-hydroxypalmitic acid, is exclusively amide-bound, presumably to the amino group of D-glucosamine. Other fatty acids, found as minor constituents, are β-hydroxymyristic, palmitic and stearic acids. Lipopolysaccharide of A. nidulans KM exhibits high anticomplementary activity in guineapig serum. It is about 800 times less toxic for adrenalectomized mice than endotoxin from Salmonella typhimurium. The isolated lipopolysaccharide reacts with rabbit antisera against living or heat-killed cells of A. nidulans in passive hemagglutination, when untreated or heated, but not when alkali-treated lipopolysaccharide is used for red blood cell sensibilization. It is concluded that lipopolysaccharide of A. nidulans KM is exposed on the surface of the cell.

Formation of the photosynthetic apparatus was induced in aerobically grown dark cultures of Rhodopseudomonas capsulata by lowering of the oxygen tension. Besides the wild type strain the carotenoid-less mutant strain A1a+ was investigated. Both strains exhibited initially a decrease of the molar ratio of total bacteriochlorophyll (Bchl) to reaction center (RC) Bchl, followed by an increase. Synthesis of RC-Bchl preceded the synthesis of light-harvesting (LH) Bchl. Activities of photophosphorylation in membrane preparations, isolated from cultures after different periods of incubation at low aeration, decreased on the basis of total Bchl from about 9 to 2 mumole ATP/mumole total Bchl-min, whereas the rate on the basis of RC-Bchl remained constant (about 500 mumole ATP/mumole RC-Bchl-min). Under the same conditions the membrane proteins were labelled with U-14C-protein hydrolysate. Corresponding to RC-Bchl the synthesis of RC-proteins dominated during the first 30 min of incubation at PO2 below 3 mm Hg. After 45-60 min of membrane formation at low aeration the synthesis of LH-complex proteins exceeded the synthesis of RC proteins. The correlations between protein and Bchl synthesis in the sequential formation of RC- and LH-complexes are discussed.

Chromosomal segments of Rhodopseudomonas capsulata carrying the ribosomal operons and cloned with the cosmid vector pHC79 have been identified by cross hybridization with γ32P-ATP labeled rRNAs. At least seven rRNA operons are present in the R. capsulata chromosome. By R-loop analyses of DNA-RNA hybrids, two distinct loop structures of sizes 1.50 kb and 2.52 kb corresponding to the 16S and 23S RNA molecules, respectively, were detected. Intact 23S RNA molecules can be isolated from R. capsulata ribosomes by sucrose density centrifugation. However, fragmentation of the 23S RNA molecule into a 16S-like molecule was observed during gel electrophoresis. Restriction mapping and hybridization of a 9 kb PstI fragment that contained one copy of the rRNA operon showed the following sequence of the RNA genes in R. capsulata 16S, 23S, and 5S. A spacer region of 0.91 kb was found between the 16S and the 23S RNA genes.

Freeze-fracture electron microscopy has been used to investigate the size, form, distribution and supramolecular organization of chlorosomes (chlorobium type vesicles) in Chloroflexus aurantiacus J-10fl, a phototrophic, filamentous gliding bacterium. The chlorosomes, that appear tightly attached to the cytoplasmic membrane, have the form of flat, elongated sacs with rounded ends, and measure 106±24×32±10×12±2nm. They are randomly distributed, and in most instances their longitudinal axis makes an angle of 30–60° to the filament axis. Each chlorosome consists of a core and an approx. 2 nm thick envelope. The core is filled with rod-shaped elements (approx. 5.2 nm in diameter) made up of globular subunits with a periodicity of approx. 6 nm. The rod elements extend the full length of the chlorosome. The membrane-associated envelope layer is marked by extremely fine striations with a repeating distance of 2.5–3nm, while the envelope layer adjacent to the cytoplasm exhibits no discernable substructure. The margins of the vesicles are delineated by regularly spaced 7 nm particles.

Three plasmids containing the transposon Tn5, i.e. pSUP201::Tn5, pACYC184::Tn5 and pJB4JI were transferred from Escherichia coli to Rhodopseudomonas capsulata in order to mutagenize the genome. Mutants defective in bacteriochlorophyll and carotenoid synthesis and mutants unable to form the photochemical reaction center or one of the light-harvesting complexes were isolated. Of special interest were mutants that could not form the light-harvesting complex B800-850. Two of these mutants synthesized only two of the three polypeptides of this complex whereas the corresponding near infrared absorbance bands were not observed. Complementation analysis with the Rprime plasmid pRPS404, which contains a 50 kb region of the genome of R. capsulata carrying most genes responsible for expression of photosynthetic apparatus, revealed that some genes of the B800-850 light-harvesting complex lie outside this photosynthetic gene cluster.

In order to distinguish between the regulatory effects of oxygen tension and light intensity on cytochrome c oxidase protein and enzymatic activity cells of Rhodobacter capsulatus were shifted from phototrophic (anaerobic, light) growth to aerobic-light, aerobic-dark and to anaerobic-dark conditions, respectively. During shift-experiments the formation of oxidase protein and regulation of oxidase activity was followed by immunological and enzymatic means. The results support the idea, that the formation of oxidase protein is regulated by oxygen tension and light intensity changes, whereas the regulation of oxidase activity seems only to be correlated to the oxygen tension. A DNA sequence involved in the oxygen-dependent regulation of cytochrome oxidase could be identified in the regulation-deficient oxidase mutant H41 of R. capsulatus. Immunological investigations of cytochrome c2 from mutant H41 demonstrated at the same time the participation of the c2-polypeptide in the regulation of cytochrome c oxidase.

The facultative photosynthetic bacterium Rhodopseudomonas capsulata was mutagenized by transfer of the plasmid pSUP201::Tn5 from Escherichia coli to R. capsulata. Mutants defective in cytochrome oxidase and other respiratory functions were selected by replica plating, NADI-reaction and immunological methods. Among 20,000 mutants no clone was detected, which lacks the 65,000-protein of the cytochrome oxidase, but many mutants have been isolated which were cytochrome oxidase deficient (or inactive). Other mutants excrete heme and cytochrome c′ into the medium and lack cytochrome c 2.

The synthesis of bacteriochlorophyll (Bchl) was inhibited in wild type strain of Rhodopseudomonas capsulata by levulinic acid (LA), δ-aminolevulinic acid of α,α′-dipyridyl. The transcription of genes for pigment-binding proteins, the synthesis and incorporation of these proteins into the membrane and the assembly of photosynthetic complexes were studied. Inhibition of Bchl synthesis did not impair formation of mRNA for pigment-binding polypeptides, but inhibited the synthesis of these proteins as well as stable incorporation into the membrane. The results let suggest, that Bchl is necessary for the stabilization of pigment-binding proteins in the membrane, and that intermediates of Bchl-synthesis affect the synthesis of these proteins. The same experiments were carried out with mutant strains blocked in Bchl synthesis. All Bchl-less mutant strains investigated here, showed transcription of photosynthetic genes at a rate which was independent of oxygen tension. The synthesis of polypeptides of reaction center, B870 and B800-850 complexes were differently affected by blocks in Bchl-synthesis. LA inhibited the synthesis of pigment-binding proteins in mutant strains similarly as in wild-type strain.

Early stages in the formation of membranes and photosynthetic units were studied under growth-limiting phototrophic and chemotrophic conditions in cells of Rhodopseudomonas capsulata. The incorporation of polypeptides, forming bacteriochlorophyll-carotinoid-protein complexes in the membrane, was followed by use of pulse-labeling and immunoprecipitation techniques. The newly synthesized polypeptides were inserted into two distinct membrane fractions at both different rates and proportions. The two membrane fractions differed in sedimentation behavior, absorption spectra and activities of the respiratory chain. The individual pigment-associated proteins did not exhibit precursor-product relationship between the two membrane fractions. The data suggest that newly synthesized polypeptides were integrated both into cytoplasmic and pre-existing intracytoplasmic membranes, where the proteins and pigments were assembled to form reaction centers and light-harvesting pigment-protein complexes.

Plasmids RP1, R68.45 and RP4::Mu cts 61 were transferred into Rhodopseudomonas capsulata from Escherichia coli. The frequency of intraspecies transfer of these plasmids in R. capsulata was 10-4–10-5 per donor. The plasmids also mobilized chromosomal genes at a low frequency. Phototrophic recombinants from matings between recipient strains defective in the photosynthetic-apparatus and wild type donors were obtained at a frequency of 10-7–10-8 per donor.

Lipopolysaccharides were found in four strains of Synechocystis. Depending on the strain, they were extracted into either the water or into the phenol phase of phenol-water extracts.

Intracytoplasmic membranes of wild type strain 37 b 4 and mutant strains A1a car-bchl-, A1a car-bchl+ ofRhodopseudomonas capsulata were isolated. The membrane proteins were solubilized and separated by polyacrylamide gel electrophoresis (methods of Takayamaet al., 1964; Weber and Osborn, 1969). The band patterns were compared with each other. From the strain A1a car-bchl+ reaction center particles were isolated by treatment of membrane with Triton X-100 followed by sucrose density gradient centrifugation. The reaction center particles were found to be enriched in reaction center bacteriochlorophyll. This pigment shows a reversible bleaching at 855 nm and a blue shift at 798 nm. The light harvesting bacteriochlorophyll portion of this fraction was 14–22% of the total bacteriochlorophyll content. The three main proteins of the reaction center particles amount to about 80% of the total protein of the particles. The molecular weights of the main proteins were estimated to be 32000, 27500 and 22500 daltons.

Der Zusammenhang zwischen der Ausbildung des intracytoplasmatischen Membransystems und dem Gehalt der Zellen an Fettsauren und Lipid-Phosphor wird an Rhodospirillum rubrum untersucht. Trotz Steigerung des Membrangehaltes nach der Uberfuhrung aerober thylakoidfreier Dunkelzellen in anaerobe Lichtbedingungen bleibt der Gehalt an Fettsauren und Lipid-Phosphor pro Gesamtzellprotein unverandert. Das gleiche Resultat ergibt sich, wenn eine Steigerung des Thylakoidgehaltes im System anaerob Normallicht (4000 Lux) → anaerob Schwachlicht (400 Lux) hervorgerufen wird. Dieses Resultat eines konstanten Fettsaurespiegels wird nicht durch eine Anderung des Bezugsystems Protein erzielt. Der Quotient Proteingehalt pro Volumen dichtgepackter Bakterien bleibt wahrend der Membransynthese konstant. Aus Licht- und Dunkelzellen werden eine Rohmembranund eine Rohzellwandfraktion angereichert. Die Wandfraktion aus aeroben Dunkelzellen enthalt einen hoheren Anteil der Gesamtfettsauren der Zelle als die Wandfraktion aus anaeroben Lichtzellen. (2-14C)-Acetat wird von wachsenden Zellen unter Normallichtbedingungen (4000 Lux) in hoher Rate eingebaut. Nach der Umschaltung auf Schwachlicht (400 Lux) wird diese Aufnahme zugleich mit dem Wachstum gestoppt. Werden aerobe Dunkelzellen in semiaerobe Lichtbedingungen uber-fuhrt, wird der Gehalt an Fettsauren und Lipid-Phosphor um 70% erhoht. Die Ergebnisse werden im Rahmen der Hypothese diskutiert, das ein groser Teil der Zellfettsauren in der Wand lokalisiert ist und das dieser Anteil koordiniert mit dem Membrangehalt verandert werden kann.

Es wird der Einflus des Sauerstoffpartialdruckes auf die Bacteriochlorophyllsynthese und die Morphogenese des photochemischen Apparates von Rhodopseudomonas capsulata untersucht. 1. Die Wachstumsrate ist in aeroben, heterotrophen Dunkelkulturen in einem relativ weiten Bereich vom Sauerstoffpartialdruck unabhangig. Die Proteinverdopplungszeit betragt in einem komplexen Medium bei 30° C und einem Partialdruck von 4–100 mm Hg, 2,5–2,75 std. Bei 150–160 mm Hg (pO2) im Medium wird das Wachstum ungefahr um 10% reduziert. Unterhalb eines kritischen Sauerstoffpartialdruckes von etwa 4 mm Hg bricht der oxydative Stoffwechsel zusammen und die Wachstumsrate nimmt demzufolge stark ab. 2. Die Rate der Bacteriochlorophyllsynthese in aeroben Dunkelkulturen wird vom Sauerstoffpartialdruck reguliert. Geringe Mengen an Bacteriochlorophyll (etwa 0,05 μg/mg Protein) sind auch in voll aeroben Kulturen enthalten (pO2 150 mm Hg). Ein Absenken des pO2 im Bereich von 100–20 mm Hg bewirkt nur eine sehr geringe Erhohung des spezifischen BChl.-Gehaltes der Zellen. Eine Erniedrigung des pO2 unter 20 mm Hg hat einen starken Anstieg der BChl.-Syntheserate zur Folge. Nach 8 Std stellt sich ein konstanter Wert des spezifischen Bacteriochlorophyllgehaltes der Zellen ein, dessen Hohe vom pO2 abhangig ist. 3. Der spezifische Bacteriochlorophyllgehalt der intracellularen Membranen steigt nach Absenken des pO2 von 160 mm Hg auf 5 mm Hg nach 2 Std von 3,3 auf 33,9 μg BChl./mg Protein an. 4. Die Biosynthese des photochemischen Apparates von Rps. capsulata wird ebenfalls durch Absenken des Sauerstoffpartialdruckes gefordert. Aber die Kinetk ist von der der Bacteriochlorophyllsynthese verschieden. Der Anstieg der Photophosphorylierungsaktivitat (PP) verlauft linear zum Proteingehalt der Membranfraktion. Dagegen nimmt das Verhaltnis PP/BChl. nach einem kurzfristigen Anstieg ab. 5. Elektronenmikroskopische Aufnahmen von Dunnschnitten zeigen sowohl in voll aeroben Dunkelkulturen (pO2 150–160 mm Hg) als auch in semiaeroben Kulturen (pO2 etwa 5 mm Hg) intracellulare Membranstrukturen. In aeroben Zellen sind vorwiegend tubulare Strukturen ausgebildet, in semiaeroben Kulturen vesiculare Thylakoide. 6. Die Ergebnisse zeigen, das die Bacteriochlorophyllproduktion, die Biosynthese des photochemischen Apparates und die Thylakoidmorphogenese vom pO2 beeinflust werden. Starke und Verlauf der Synthesen werden aber unterschiedlich reguliert.

Der Gehalt an reduzierten Nicotinamid-adenin-dinucleotiden bei Rhodospirillum rubrum, Rhodopseudomonas spheroides und Rps. capsulata wird beim Absenken des pO2 erst zwischen 0,2 und 0,5 mm Hg deutlich erhoht.

Membranfunktionen aus anaerob im Licht gewachsenen Zellen von Rps. capsulata und aus Zellen nach Anzucht im Dunkeln unter verschiedenen konstanten Sauerstoffpartialdrucken (5, 150, 400 Torr) wurden untersucht. Aus dem Vergleich ihres Aufbaues (Proteinmuster) und ihrer photosynthetischen und respiratorischen Aktivitat (Funktionsmuster) lies sich eine Vorstellung uber das Differenzierungsgeschehen des gesamten Membransystems von Rps. capsulata ableiten.

Der neu isolierte Stamm W von Bdellovibio bacteriovorus infiziert und lysiert Rhodospirillum rubrum F und alle anderen untersuchten Athiorhodaceae, nicht aber Pseudomonas aeruginosa und Spirillum serpens. Er befallt auch zahlreiche Enterobacteriaceae und von den grampositiven Bakterien Streptococcus faecalis und Lactobacillus plantarum.

Two carotenoid less mutant strains of Rhodopseudomonas capsulata were isolated. The strain A1a pho- was not able to grow photosynthetically and to synthesize bacteriochlorophyll. However, this organism produced protochlorophyll (phytol ester of Mg-2-vinylpheoporphyrin a5 monomethylester) and protopheophytin. Both pigments were excreted as a macromolecular complex. The intracellular membrane system was poorly developed. A revertant strain of A1a (pho+) was isolated which was able to grow anaerobically in the light as well as aerobically in the dark. The generation time under photosynthetic conditions amounted to 16 hrs whereas under aerobic conditions in the dark that was found to be 2.8 hrs. In addition to bacteriochlorophyll, which was found exclusively in the membrane fraction, protochlorophyll and protopheophytin were synthesized and excreted. A small amount of these pigments was also found intracellulary in the membrane fraction. The structure of the well developed intracytoplasmic membrane reticulum was described.

A lipopolysaccharide was isolated from cell walls of Anacystis nidulans by extraction with 45% aqueous phenol at 65°, and further purified by repeated high speed centrifugation. It contains 30–40% of lipid and about 60% of carbohydrate components. The carbohydrate moiety contains predominantly mannose and smaller amounts of galactose, glucose, fucose, rhamnose, 2-keto-3-deoxyoctonate, glucosamine and a second aminosugar. The latter was identified as a 2-amino-2-deoxyheptose with the gluco-configuration from C3 to C7. Thelipid moiety contains glucosamine and fatty acids (C22:0, C18:2, C16:0, C12:0 and C14:βOH). The lipopolysaccharide has a very low phosphate content and does not contain heptose. It shows low pyrogenicity in rabbits and it is not toxic in mice.

Adsorptionskinetiken mit verschiedenen Rhodopseudomonas palustris-Stammen ergaben, das Rp 1-Phagen nur an Stamm 1 e 5 adsorbieren. Als Adsorptionskonstante wurde ein Wert von K=3,8·10-10 ml/min ermittelt. Wahrend des Wachstums der Wirtsbakterien werden die Rp 1-Phagen nur in der Teilungsebene und an einem Zellpol adsorbiert. Die Phagen adsorbieren auch an den intracytoplasmatischen Membranen. Die Spezifitat dieser Adsorption wird diskutiert.

The structure and formation of polyphosphate-granules has been investigated by means of ultrathin sections through Mycobacterium phlei.

Thylakoide vonRhodospirillum rubrum, Rhodopseudomonas viridis undRhodopseudomonas capsulata wurden durch Behandlung mit Phenol-Ameisensaure in makromolekulare, in der Gelelektrophorese wandernde Fraktionen aufgespalten. Dabei ergaben sich vier deutlich hervortretende Hauptfraktionen, die zum Teil noch in Unterfraktionen aufzulosen sind.

Die in einer fruheren Arbeit postulierten Untergruppen innerhalb der Art Rps. gelatinosa werden naher charakterisiert. Die Gruppen unterscheiden sich in der Generationszeit, der Schleimproduktion, der Tendenz, sich in der Submerskultur abzusetzen, der Substratverwertung und den Eigenschaften des in vivo-Absorptionsspektrums. Artspezifisch und charakteristisch fur alle Stamme ist die Fahigkeit zur Gelatineverflussigung, die Nutzung von Asparagin als C-Quelle und das Unvermogen, autotroph zu wachsen.

Eine bacteriochlorophyllfreie Mutante von Rhodospirillum rubrum wird beschrieben. Diese Mutante scheidet die Bacteriochlorophyllvorstufen Phaeophorbid a und 2-Devinyl-2-α-Hydroxyathyl-Phaeophorbid a unter semiaeroben Bedingungen in das Kulturmedium aus. Beide Pigmente sind mit einem Tragermolekul zu einem Komplex verbunden. Die Analyse des Komplexes ergab folgende Zusammensetzung: 49% Protein, 30% Pigment, 11% Lipide, 3% Zucker, sowie eine geringe Menge Phosphor (0,2%). Die Aminosaurezusammensetzung des Proteinanteils wird angegeben. Die Fettsauren werden gaschromatographisch bestimmt. Die Zuckerkomponente ist anders zusammengesetzt als das Lipopolysaccharid aus Rhodospirillum rubrum. Das Molekulargewicht der kleinsten Proteinuntereinheit betragt 16500, das Molekulargewicht des Pigmentkomplexes ergibt sich daraus mit 34000. Typische Thylakoide werden in der Mutante nicht ausgebildet. Die Notwendigkeit einer ungestort ablaufenden Bacteriochlorophyllsynthese fur die normale Thylakoidmorphogenese wird diskutiert.

Heterotroph aerob im Dunkeln angezogene Kulturen von Rhodospirillum rubrum beginnen sofort nach Umstellung auf Anaerobiose mit der Bacteriochlorophyllbildung.

The present paper deals with the isolation, and chemical and serological characterization of the O-antigens (lipopolysaccharides, LPS) of the photosynthetic gram-negative bacterium Rhodopseudomonas viridis. The LPS are extractable with hot phenol/water, but unlike the phenol-soluble LPS of the closely related species Rhodopseudomonas palustris, the R. viridis O-antigens are preferentially extracted into the water phase. A mixture of phenol/chloroform/petroleum ether (PCP-method) does not extract the R. viridis LPS.

Die Zellwande von Anacystis nidulans enthalten 23,8% Zucker (berechnet als Glucose), 8,9% Gesamtstickstoff, 0,1% Gesamtphosphor, 27,6% Protein und 36% Lipide. Die Polysaccharidfraktion wurde durch Phenol-Wasser-Extraktion isoliert. Sie scheint keine Aminozucker und keine sauren Zucker zu enthalten. Als Komponenten wurden Mannose, das den grosten Anteil stellt und Glucose nachgewiesen. Zwei weitere Zucker konnten nicht identifiziert werden. Sie haben die gleichen Rf-Werte wie Galaktose und Fucose.

Es wird das Vorkommen von Polysomensaulen bei Rhodopseudomonas palustris beschrieben. An Hand der Daten ergab sich, das diese Polysomen aus zwei helixformig angeordneten Ribosomenstrangen aufgebaut sind, die eine linksdrehende Schraube bilden. Der Querschnitt der Schraube zeigt hexagonale Anordnung der Ribosomen. Der Steigungswinkel der Helices betragt 200, der Gesamtdurchmesser der hexagonalen Polysomensaule betragt 375 A. Diese Polysomenart kommt lediglich in der begeiselten Polregion vor und ist dicht unter der Cytoplasmamembran lokalisiert. Die Polysomen stehen mit der Cytoplasmamembran in Kontakt. Ihre Langsachse lauft parallel zur Plasmamembran.

Eine Methode zur quantitativen Bestimmung des Fettsauregehaltes im Mikrogrammbereich wird angegeben und auf Spezifitat untersucht. Thylakoide aus Rhodospirillum rubrum und Rhodopseudomonas capsulata enthalten 330 bzw. 350 μg Fettsauren/mg Protein und 16,1 bzw. 15,4 μg Lipid-Phosphor/mg Protein. In aeroben Dunkelkulturen beider Organismen werden 100–120 μg Fettsauren und 3,0–4,3 μg Lipid-Phosphor pro mg Protein gefunden. In Thylakoiden sind 15–20%, in ganzen Zellen 25–45% der Fettsauren nicht in Phospholipiden vom Glycerintyp gebunden.

Die Thylakoide aus Rhodospirillum rubrum und Rhodospirillum molischianum werden nach Homogenisation der Zellen mit Ultraschall durch fraktionierte Zentrifugation isoliert. An diese Membranstrukturen ist das System der Photophosphorylierung gebunden. Die Aktivitat dieses Systems in Abhangigkeit vom Redoxpotential des Mediums wird untersucht. Die starkste Bindung anorganischen Phosphates wird unter Edelgasatmosphare bei Zusatz von Spuren eines Elektronendonators (0,07 μmol Succinat je Ansatz) beobachtet. Die cyclische Photophosphorylierung wird einerseits durch Sauerstoff und oxydierende Verbindungen wie K3Fe(CN)6 anderseits durch „Uberreduktion” mittels reduzierter Redoxverbindungen wie 2,6-Dichlorphenolindophenol oder Phenazinmethosulfat (beide reduziert durch Ascorbat) unter Wasserstoffatmosphare gehemmt. Die Sauerstoffhemmung kann durch reduziertes Phenazinmethosulfat zu 50% aufgehoben werden. Antimycin A blockiert die lichtabhangige Phosphorylierung; 2,4-Dinitrophenol dagegen hemmt kaum. Die zellfreien Systeme beider Arten zeigen die gleiche Abhangigkeit vom Redoxpotential obwohl R. rubrum wesentlich sauerstofftoleranter ist als R. molischianum und auch durch oxydative Phosphorylierung im Dunkeln ATP bilden kann. Die Befunde sprechen fur eine Unabhangigkeit der cyclischen Photophosphorylierung von der Atmungskette und fur eine starke Ubereinstimmung im Aufbau der Elektronentransportsysteme fur die cyclische Photophosphorylierung bei R. rubrum und R. molischianum.

A continuous culture apparatus is described, which allows cultivation of photosynthetic bacteria anaerobically in the light and semiaerobically in the dark at constant oxygen tensions. The growth-parameters 1. substrate concentration at half maximum growth rate (Ks) and 2. yield (Y) forRhodopseudomonas capsulata are calculated.

In wachsenden Kulturen von Mycobacterium phlei erfolgt die Bildung metachromatischer Granula am raschesten in geschuttelten Submerskulturen, wenn zum Beimpfen Material von Agarkulturen verwendet wird.