Isolation and characterization of Reyranella massiliensis gen. nov., sp. nov. from freshwater samples by using an amoeba co-culture procedure.

The analysis of three water samples from two cooling towers and one river allowed us to isolate three strains of a novel species of the class Alphaproteobacteria which is phylogenetically related to uncultured alphaproteobacteria. Based upon 16S rRNA gene sequence analysis and phenotypic characterization, we propose to name this novel species Reyranella massiliensis gen. nov., sp. nov., type strain 521(T) ( = CSUR P115(T)  = DSM 23428(T)). The most closely related cultivable micro-organism to this novel bacterium is a member of the genus Magnetospirillum.

Isolation and characterization of cytoplasmic membranes and chlorosomes from the green bacterium Chloroflexus aurantiacus.

A method was developed which allows the isolation and purification of cytoplasmic membranes and chlorosomes from cells of Chloroflexus aurantiacus grown under different light conditions. The dipolar ionic detergent Deriphat (0.08%) and a sodium iodide gradient centrifugation were used in isolating cytoplasmic membranes. Chlorosomes were prepared with 0.16% of the dipolar ionic detergent Miranol and purified by a sucrose gradient centrifugation. Cytoplasmic membrane fractions prepared from either high- (3,000 W m-2), medium-(200 W m-2) or low- (7 W m-2) light-grown cells had near infrared absorption bands at 866, 808, and 755 nm in a constant characteristic absorbance ratio of 6:3.8:1. In all cytoplasmic membrane preparations, the amount of bacteriochlorophyll a (Bchl a) per cytochrome, the amount of Bchl a per reaction center, and reaction center per milligram of cytoplasmic membrane protein was found to be constant. No Bchl c was present. Five respiratory enzyme activities have been measured in the cytoplasmic membrane fraction. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of denatured cytoplasmic membrane showed many bands, but a major polypeptide with an apparent molecular weight of 8,000. In contrast, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of purified chlorosomes did not contain the 8,000-molecular-weight band but revealed only three distinct protein bands with molecular weights of 15,000, 12,000, and 6,000. Isolated chlorosomes contained Bchl c and a small, yet constant, amount of Bchl a (absorbing at 790 nm) in a molar ratio of 25:1. The data indicated that the components of the photosynthetic apparatus in the cytoplasmic membrane of Chloroflexus aurantiacus remained constant and only the amount of antenna Bchl c varied with light conditions.

Semiaerobic induction of bacteriochlorophyll synthesis in the green bacterium Chloroflexus aurantiacus.

Comparison of Chloroflexus aurantiacus J-10-fl cells by freeze-fracture electron microscopy showed that cell shape and dimensions did not depend on oxygen tension or light intensity during growth. The major morphological difference between cells cultured anaerobically in the light and aerobically in the dark was the absence of chlorosomes in aerobically grown cells. C. aurantiacus cells cultured aerobically in the dark began bacteriochlorophyll synthesis immediately when shifted to either phototrophic or semiaerobic conditions. Cells adapting to phototrophic conditions grew to the same density and synthesized as much bacteriochlorophyll as nonadapting phototrophic cultures grown at the same light intensity. Cells adapting to reduced oxygen tension (semiaerobic conditions) in the dark entered an 8- to 12-h growth lag during which the bacteriochlorophyll content increased significantly. Despite variations in the initial bacteriochlorophyll content and in the length of the growth lag, the amounts of bacteriochlorophyll a and c were constant at the end of the semiaerobic growth lag. At later times during adaptation to semiaerobic conditions, after growth resumed, variations in the ratio of bacteriochlorophyll c/bacteriochlorophyll a were observed and suggested independent regulation of the two bacteriochlorophylls.

[Growth of purple sulfur bacteria in the dark in anaerobic conditions]. / Rost purpurnykh serobakterii v temnote v anaérobnykh usloviiakh

Phototrophic sulphur bacteria Chromatium minutissimum 1 C, Ectothiorhodospira shaposhnikovii 1, and various strains of Thiocapsa roseopersicina grow in the dark under anaerobic conditions (hydrogen or argon) on organic media in the presence of sulphide, thiosulphate or molecular sulphur. Ect. shaposhnikovii grows also in the presence of sulphite, cysteine, methionine, glutathione, and, to a less degree, sulphates. Cultures of Ect. shaposhnikovii growing in the dark under anaerobic conditions assimilate fructose and liberate pyruvate, lactate, formiate and traces of acetate into the medium. These cultures can grow in the dark under anaerobic conditions assimilating not only fructose but also various C4-dicarboxylic acids, lactate, pyruvate, butyrate, and acetate. Thiocapsa grows on media containing malate, succinate, lactate, pyruvate, and acetate. Thiocapsa reseopersicina SL assimilates in the dark under anaerobic conditions fructose, glucose, glycerol, pyruvate, lactate, and acetate.

[On the ecology of marine chromatiaceae and chlorobiaceae (author's transl)]. / Sur l'écologie des Chromatiaceae et des Chlorobiaceae marines

Number and genera (types) of phototrophic red and green sulfur bacteria have been determined in the upper layer of eleven marine sediment samples from the euphotic zone in the Mediterranean Sea. Origin and nature of the sediment samples are given as well as their pH, total nitrogen and sulfide content. The results show that the sediments studied did not provide good growth conditions for Chromatiaceae (Chromatium, Thiocystis, Thiocapsa) and Chlorobiaceae (Prosthecochloris). The total number of these bacteria varied in agreement with the total nitrogen content (organic matter) of the samples; the organic matter content is, therefore, of primary importance for the occurrence of the red and green sulfur bacteria in the samples.