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A new phototrophic purple bacterium was isolated from a flat, laminated microbial mat in a salt marsh near Woods Hole, Mass., USA. The spiral-shaped bacterium was highly motile and had bipolar tufts of flagella and intracytoplasmic membranes of the vesicular type. The major photosynthetic pigments were identified as the carotenoid tetrahydrospirilloxanthin and bacteriochlorophyll b. The long wavelength in vivo absorption maximum of the bacteriochlorophyll was at 986 nm. The marine bacterium showed optimal growth in the presence of 2% NaCl. It utilized a number of organic substrates as carbon and energy sources and required vitamins and sulfide as a reduced sulfur source for growth. In the presence of sulfide, elemental sulfur globules were formed outside the cells. Elemental sulfur was not further oxidized to sulfate. The new isolate had a unique lipid and fatty acid composition, and according to the 16S rRNA gene sequence, it is most similar to Rhodospirillum rubrum. It is described as a new species and assigned to a new genus with the proposed name Rhodospira trueperi.

A new, rod-shaped, Gram-negative, non-sporing sulfate reducer (strain Ani1) was enriched and isolated from marine sediment with aniline as sole electron donor and carbon source. The strain degraded aniline completely to CO2 and NH3 with stoichiometric reduction of sulfate to sulfide. Strain Ani1 also degraded aminobenzoates and further aromatic and aliphatic compounds. The strain grew in sulfide-reduced mineral medium supplemented only with vitamin B12 and thiamine. Cells contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P582, but no desulfoviridin. Strain Ani1 is described as a new species of the genus Desulfobacterium D. anilini. Marine enrichments with the three dihydroxybenzene isomers led to three different strains of sulfate-reducing bacteria; each of them could grow only with the isomer used for enrichment. Two strains isolated with catechol (strain Cat2) or resorcinol (strain Re10) were studied in detail. Both strains oxidized their substrates completely to CO2, and contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P 582. Desulfoviridin was not present. Whereas the rod-shaped catechol oxidizer (strain Cat2) was able to grow on 18 aromatic compounds and several aliphatic substrates, the coccoid resorcinol-degrading bacterium (strain Re10) utilized only resorcinol, 2,4-dihydroxybenzoate and 1,3-cyclohexanedion. These strains could not be affiliated with existing species of sulfate-reducing bacteria. A further coccoid sulfate-reducing bacterium (strain Hy5) was isolated with hydroquinone and identified as a subspecies of Desulfococcus multivorans. Most-probable-number enumerations with catechol, phenol, and resorcinol showed relatively large numbers (10(4)-10(6) per ml) of aryl compound-degrading sulfate reducers in marine sediment samples.

Anaerobic sea or fresh water media with acetate and elemental sulfur yielded enrichments of a new type of strictly anaerobic, rod-shaped, laterally flagellated, Gram-negative bacterium. Three pure culture-strains from different sulfide-containing sea water sources were characterized in detail and are described as a new genus and species Desulfuromonas acetoxidans. The new bacterium is unable to ferment organic substances; it obtains energy for growth by anaerobic sulfur respiration. Acetate, ethanol or propanol can serve as carbon and energy source for growth; their oxidation to CO2 is stoichiometrically linked to the reduction of elemental sulfur to sulfide. Organic disulfide compounds, malate or fumarate are the only other electron acceptors used. Butanol and pyruvate are used in the presence of malate only; no other organic compounds are utilized. Biotin is required as a growth factor. The following dry weight yields per mole of substrate are obtained: in the presence of sulfur: 4.21 g on acetate, 9.77 g on ethanol; in the presence of malate: 16.5 g on acetate, 34.2 g on ethanol and 46.2 g on pyruvate. Accumulations of cells are pink; cell suspensions exhibit absorption spectra resembling those of c-type cytochromes (abs. max. at 419, 523 and 553 nm). Malate-ethanol grown cells contain a b-type cytochrome in addition. In the presence of acetate, ethanol or propanol, Desulfuromonas strains form robust growing syntrophic mixed cultures with phototrophic green sulfur bacteria.

Three strains (2ac9, 3ac10 and 4ac11) of oval to rod-shaped, Gram negative, nonsporing sulfate-reducing bacteria were isolated from brackish water and marine mud samples with acetate as sole electron donor. All three strains grew in simple defined media supplemented with biotin and 4-aminobenzoic acid as growth factors. Acetate was the only electron donor utilized by strain 2ac9, while the other two strains used in addition ethanol and/or lactate. Sulfate served as electron acceptor and was reduced to H2S. Complete oxidation of acetate to CO2 was shown by stoichiometric measurements with strain 2ac9 in batch cultures using sulfate, sulfite or thiosulfate as electron acceptors. With sulfate an average growth yield of 4.8 g cell dry weight was obtained per mol of acetate oxidized; with sulfite or thiosulfate the growth yield on acetate was about twice as high. None of the strains contained desulfoviridin. In strain 2ac9 cytochromes of the b- and c-type were detected. Strain 2ac9 is described as type strain of the new species and genus, Desulfobacter postgatei.

Colony counts of acetate-, propionate- and L-lactate-oxidizing sulfate-reducing bacteria in marine sediments were made. The vertical distribution of these organisms were equal for the three types considered. The highest numbers were found just beneath the border of aerobic and anaerobic layers. Anaerobic mineralization of acetate, propionate and L-lactate was studied in the presence and in the absence of sulfate. In freshwater and in marine sediments, acetate and propionate were oxidized completely with concomitant reduction of sulfate. L-Lactate was always fermented. Lactate-oxidizing, sulfate-reducing bacteria could only be isolated from marine sediments, they belonged to the genus Desulfobacter and oxidized only acetate and ethanol by sulfate reduction. Propionate-oxidizing, sulfate-reducing bacteria belonged to the genus Desulfobulbus. They were isolated from freshwater as well as from marine sediments and showed a relatively large range of usable substrates: hydrogen, formate, propionate, L-lactate and ethanol were oxidized with concomitant sulfate reduction. L-Lactate and pyruvate could be fermented by most of the isolated strains.

A new bacteriochlorophyll has been isolated by thin layer chromatography from all strains of the brown-colored Chlorobiaceae Chlorobium phaeobacteroides and Chlorobium phaeovibriodes. The new bacteriochlorophylle--like the bacteriochlorophylls c and d--represents the major amounts of bacteriochlorophyll a. Bacteriochlorophyll e can be differentiated from the bacteriochlorophylls c and d by its absorption maxima in aceton and its different Rf-value in the thin layer chromatogram. The structure of the new bacteriochlorophyll e has been elucidated on the basis of mass spectra, 1H-and 13C-NMR-spectra, the UV/VIS-spectrum as well as IR-, ORD-, and CD-spectra. The new bacteriochlorophyll has the same relationship to bacteriochlorophyll c as chlorophyll b from green plants to chlorophyll a; therefore, bacteriochlorophyll e represents the first formyl-substituted chlorophyll from bacteria. Similar to the bacteriochlorophylls c and d, the new bacteriochlorophyll e consists of a mixture of at least three homologues which differ from each other by different substituents on the pyrrol rings II and III.

A flexing and gliding green sulfur bacterium has been isolated from marine sources off the North East coast of the USA. Chloroherpeton thalassium is an obligate phototroph, and requires CO2 and S2 for growth; some organic acids can contribute to cell carbon, and N2 may be fixed. The cells contain typical chlorosomes, and gas vesicles may be present. Bacteriochlorophyll c is the main light harvesting pigment, and a small quantity of bacteriochlorophyll a is also present. Over 80% of the carotenoid is gamma-carotene. DNA base composition of the isolates ranges from 45.0-48.2 mol% G + C.

Acetate-oxidizing sulfate-reducing bacteria of the Desulfotomaculum acetoxidans type have been enriched from animal manure, rumen content and dung contaminated freshwater habitats, indicating that they are primarily intestinal bacteria. Sporulation was observed only when acetate was the organic substrate; with butyrate, which allowed faster growth than acetate, spore formation never occurred. The cone-shaped highly refractile areas adjacent to the spores in spore-forming mother cells were shown to be gas vacuoles. Biotin was the only growth factor required by Desulfotomaculum acetoxidans strain 5575 in minimal media with sulfate and acetate or other organic substrates.

A new strictly anaerobic, polarly flagellated, sporing, acetate-oxidizing, sulfate-reducing bacterium was isolated from anaerobic fresh or sea water mud samples. The oxidation of acetate to CO2 is stoichiometrically linked to the formation of H2S from sulfate. Ethanol, butanol and butyrate are also used. Hydrogen, lactate or pyruvate are not used as electron donors; organic substances are not fermented. A cytochrome of the b-type and a supposed sulfite reductase, P582, were detected spectrophotometrically. An emended description of the genus Desulfotomaculum is proposed which includes the new bacterium as the species Desulfotomaculum acetoxidans.