Karin Schmidt

Die Carotinoide der Thiorhodaceae

ZusammenfassungEs werden Isolierung und Eigenschaften eines neuen Carotinoids beschrieben. Es liegt in Chromatium okenii als einziges Carotinoid vor, ist in relativ sehr hoher Konzentration (50 μg/mg Protein) enthalten und durch eine konjugierte Ketogruppe und eine tertiäre Methoxylgruppe charakterisiert. Es wird der Name “Okenon” vorgeschlagen. Phytofluen, ξ-Carotin, Neurosporin und Lycopin wurden als Begleitcarotinoide lediglich in Zellen nachgewiesen, die in Gegenwart von Diphenylamin gewachsen waren.SummaryIsolation and properties of a new carotenoid are described. It was found in Chromatium okenii as the only carotenoid in a remarkably high concentration (50 μg/mg protein) and is characterized by the presence of a conjugated keto-group and a tertiary methoxyl-group. We suggest to name the new carotenoid okenone. Phytofluene, ξ-carotene, neurosporene and lycopene were found only in cells grown in the presence of diphenylamine.

A comparative study on the composition of chlorosomes (Chlorobium vesicles) and cytoplasmic membranes from Chloroflexus aurantiacus strain Ok-70-fl and Chlorobium limicola f. thiosulfatophilum strain 6230

Highly purified fractions of chlorosomes and cytoplasmic membranes were isolated from Chloroflexus aurantiacus Ok-70-fl and Chlorobium limicola 6230. These fractions were comparatively analyzed for their pigmentation, phospholipid, glycolipid, and cytochrome c content as well as for their specific activities of succinate dehydrogenase and NADH-oxidase. The data showed that there are some differences in pigmentation and phospholipid content between the isolated fractions of Chloroflexus and Chlorobium. Chlorosomes of Chloroflexus contained a specific BChl a-complex with a characteristic absorption maximum at about 790 nm. This BChl a-complex could not be detected in spectra of chlorosomes from Chlorobium. The near infrared region of the spectra of the isolated cytoplasmic membranes of both organisms revealed considerable differences: The BChl a-complexes of Chloroflexus membranes exhibited peaks at 806 and 868 nm whereas the membranes of Chlorobium had a single BChl a-peak at 710 nm. In contrast to the findings with Chlorobium the chlorosomes of Chloroflexus contained at least twice as much phospholipids as did the cytoplasmic membranes. In Chlorobium the phospholipid content of cytoplasmic membranes is three times that of their chlorosomes. The distribution of all other components (carotenoid composition, enzyme activities, cytochrome c content, and glycolipids) was about the same in both strains. From the data it was concluded that differences in the organization of the photosynthetic apparatus are mainly based on differences of the organization of the photosynthetic units in the cytoplasmic membrane and probably the kind of linkage of the light harvesting system in the chlorosomes with the reaction center in the cytoplasmic membranes.

The isolation and partial characterisation of the light-harvesting pigment-protein complement of Rhodopseudomonas acidophila

The photosynthetic membranes of two strains of Rhodopseudomonas acidophila (7750 and 7050) have been resolved into their constituent light-harvesting pigment-protein complexes. Four different types of antenna complexes (B880, B800–830 and two types of B800–850) have been isolated and partially purified. In each case the light-harvesting pigments (bacteriochlorophyll a and carotenoids) are bound to rather low molecular weight polypeptides (in the 5000–9000 region).

Kefiran, a novel polysaccharide produced in the kefir grain by Lactobacillus brevis.

Summary1.Almost half of the material embedding the microbial population of the kefir grain consists of kefiran, a polysaccharide consisting of equal amounts of galactose and glucose with an

Some properties ofAchromatium oxaliferum

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Changes in carotenoid biosynthesis caused by variations of growth conditions in cultures of Rhodopseudomonas acidophila strain 7050

of + 68.0° (C=1, H2O).2.Kefiran is the capsular material of the large rod-shaped bacteria which predominate in the grains and have the properties of Lactobacillus brevis.

Carotenoid composition in the genus Ectothiorhodospira pelsh

The development of chlorosomes and their pigmentation were studied by growing Chloroflexus aurantiacus strain Ok-7o-fl first under conditions under which BChl c-synthesis is low (50°C, 2000 lux and 30°C, 1500 lux) and subsequently under conditions promoting high BChl c-synthesis (50°C, 400 lux). Electron microscopic observations on and chemical analyses of isolated cell components showed that in BChl c-depleted cells chlorosome-like structures (“chlorosome bags”) are attached to fragments of cytoplasmic membranes. These chlorosome bags exhibit a periodic fine structure caused by the construction of the baseplates of the chlorosomes. The baseplates are closely attached to the cytoplasmic membrane, they are rich in phospholipids and apparently contain a 790 nm-BChl a-complex. Chlorosome bags of BChl c-depleted cells always contain a limited amount of light-harvesting pigment complexes (BChlc, γ- and β-carotene). The light-harvesting system is restored (50°C, 400 lux) by first refilling the existing chlorosome bags before cell division takes place.

Carotenoids of purple nonsulfur bacteria

Studies on cells harvested from the natural habitat showed thatA. oxaliferum is gram-negative and catalase-negative. Electron micrographs of carefully fixed cells revealed the presence of peritrichously arranged appendages with a minimum thickness of 90 Å as well as capsular slime. The hypothesis is advanced that the gliding motility ofAchromatium is caused by peritrichous bacterial flagella beating in a slime layer that surrounds the cell.