Rhodobacter veldkampii, a new species of phototrophic purple nonsulfur bacteria

We describe a new species of purple nonsulfur bacteria, which has the ability to grow under photoautotrophic growth conditions with sulfide as an electron donor and shows the characteristic properties of Rhodobacter species (i.e., ovoid to rod-shaped cells, vesicular internal photosynthetic membranes, bacteriochlorophyll a and carotenoids of the spheroidene series as photosynthetic pigments). In its physiological properties this new species is particularly similar to the recently described species Rhodobacter adriaticus, but it shows enough differences compared with R. adriaticus and the other Rhodobacter species to be recognized as a separate species. In honor of Hans Veldkamp, a Dutch microbiologist, the name Rhodobacter veldkampii sp. nov. is proposed

Correlation of viable cell counts, metabolic activity of sulphur-oxidizing bacteria and chemical parameters of marine sediments

Viable counts of aerobic and anaerobic chemotrophic sulphur-oxidizers as well as phototrophic sulphur bacteria were determined in sediment samples taken from two different areas along the Baltic Sea shore which were known to regularly develop sulphidic conditions. Depth profiles of bacterial cell counts were correlated with concentration profiles of chloride, sulphate, sulphide, nitrate and phosphate in the pore water of these sediments and with potential activities of nitrate reduction, thiosulphate transformation and sulphate formation. The data revealed a complex multilayered structure within the sediments. Sulphide was released into the water from sediments of both sampling areas, but it was found that light and the availability of oxygen significantly reduced this amount. In the highly reduced sediment at Hiddensee, the highest numbers of phototrophic and chemotrophic sulphur-oxidizers were found near the sediment surface. Therefore, it was concluded that the combined action of both groups of bacteria most efficiently oxidizes reduced sulphur compounds in the top layers of the sediments. Nitrate may replace oxygen as final electron acceptor and will support oxidation of sulphide, in particular when oxygen and light are limitin

Thioalkalicoccus limnaeus gen. nov., sp. nov., a new alkaliphilic purple sulfur bacterium with bacteriochlorophyll b

Four strains of purple sulfur bacteria containing bacteriochlorophyll b were isolated from cyanobacterial mats of soda lakes in the steppe of south-east Siberia, Russia. Cells of all strains were cocci without gas vesicles. Eventually, cells with flagella were seen in the electron microscope, but motile cells were observed very rarely in cultures. Internal photosynthetic membranes were of the tubular type. Photosynthetic pigments were bacteriochlorophyll b and carotenoids with spectral characteristics similar to 3,4,3',4'-tetrahydrospirilloxanthin. The bacteria were obligately phototrophic and strictly anaerobic. Hydrogen sulfide and elemental sulfur were used as photosynthetic electron donors. Thiosulfate was not used. During growth on sulfide, sulfur globules were formed as intermediate oxidation products, deposited inside the cells and centrally located. In the presence of sulfide and sodium bicarbonate, acetate, malate, propionate, pyruvate, succinate, fumarate and yeast extract were photoassimilated. Growth factors were not required. The new bacterium is an obligate alkaliphile growing at pH 8-10 with an optimum at pH 9. It showed good growth up to 6.0% sodium chloride and up to 8.5% sodium carbonates. Phenotypically, it is similar to Thiococcus pfennigii, but different by virtue of its alkaliphily and salt tolerance. The DNA G+C content was 63.6-64.8 mol %, compared to 69.4-69.9 mol % for Thiococcus pfennigii. The 16S rDNA sequence of strain A26T was approximately 92% similar to that of Thiococcus pfennigii DSM 226 and therefore a new genus and species name, Thioalkalicoccus limnaeus gen. nov. and sp. nov., are proposed for the new bacteriu

Corals as Source of Bacteria with Antimicrobial Activity

In this study we examined marine bacteria associated with different corals (Porites lutea, Galaxea fascicularis, Acropora sp. and Pavona sp.) collected from vicinity of Panjang island, Jepara, North Java Sea, Indonesia for their antimicrobial activities against the bacteria Echerichia coli, Bacillus subtilis, Staphylococcus lentus and the yeast Candida glabrata. A total of 13 bacterial isolates belonged to the members of Bacillus, Vibrio, Micrococcus, Pseudoalteromonas, Arthrobacter and Pseudovibrio were found to inhibit the growth of at least one test strain. Further examinations among the biologically active strains by using PCR with specific primers of non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) resulted in the presence of NRPS gene fragments in the 2 members of Bacillus and Micrococcus and PKS gene fragments in the 2 members of Bacillus and Vibrio. Following cloning and sequencing of the PCR products, the fragments from Bacillus BM1.5 and Micrococcus BJB showed sequence identity with peptide synthetase genes of Bacillus subtilis (61 %) and Actinoplanes teichomyceticus (62.4%). On the other hand, PKS-amplifying strains Bacillus BJ.7 and Vibrio MJ.5 showed closest sequence identity with polyketide synthase genes of Bacillus subtilis (73%) and Anabaena sp 90 (62%), respectively

A three dimensional model of the photosynthetic membranes of Ectothiorhodospira halochloris

The three dimensional organization of the complete photosynthetic apparatus of the extremely halophilic, bacteriochlorophyll b containing Ectothiorhodospira halochloris has been elaborated by several techniques of electron microscopy. Essentially all thylakoidal sacs are disc shaped and connected to the cytoplasmic membrane by small membraneous ldquobridgesrdquo. In sum, the lumina of all thylakoids (intrathylakoidal space) form one common periplasmic space. Thin sections confirm a paracrystalline arrangement of the photosynthetic complexes in situ. The ontogenic development of the photosynthetic apparatus is discussed based on a structural model derived from serial thin sections

Ultraviolet and Multiwavelength Variability of the Blazar 3C 279: Evidence for Thermal Emission

The gamma-ray blazar 3C 279 was monitored on a nearly daily basis with IUE, ROSAT and EGRET for three weeks between December 1992 and January 1993. During this period, the blazar was at a historical minimum at all wavelengths. Here we present the UV data obtained during the above multiwavelength campaign. A maximum UV variation of ~50% is detected, while during the same period the X-ray flux varied by no more than 13%. At the lowest UV flux level the average spectrum in the 1230-2700 A interval is unusually flat for this object (~1). The flattening could represent the lowest energy tail of the inverse Compton component responsible for the X-ray emission, or could be due to the presence of a thermal component at ~20000 K possibly associated with an accretion disk. The presence of an accretion disk in this blazar object, likely observable only in very low states and otherwise hidden by the beamed, variable synchrotron component, would be consistent with the scenario in which the seed photons for the inverse Compton mechanism producing the gamma-rays are external to the relativistic jet. We further discuss the long term correlation of the UV flux with the X-ray and gamma-ray fluxes obtained at various epochs. All UV archival data are included in the analysis. Both the X- and gamma-ray fluxes are generally well correlated with the UV flux, approximately with square root and quadratic dependences, respectively.Comment: 22 pages, Latex, 7 PostScript figures, to appear in The Astrophysical Journa

A–C Estrogens as Potent and Selective Estrogen Receptor-Beta Agonists (SERBAs) to Enhance Memory Consolidation under Low-Estrogen Conditions

Estrogen receptor-beta (ERβ) is a drug target for memory consolidation in postmenopausal women. Herein is reported a series of potent and selective ERβ agonists (SERBAs) with in vivo efficacy that are A–C estrogens, lacking the B and D estrogen rings. The most potent and selective A–C estrogen is selective for activating ER relative to seven other nuclear hormone receptors, with a surprising 750-fold selectivity for the β over α isoform and with EC50s of 20–30 nM in cell-based and direct binding assays. Comparison of potency in different assays suggests that the ER isoform selectivity is related to the compound’s ability to drive the productive conformational change needed to activate transcription. The compound also shows in vivo efficacy after microinfusion into the dorsal hippocampus and after intraperitoneal injection (0.5 mg/kg) or oral gavage (0.5 mg/kg). This simple yet novel A–C estrogen is selective, brain penetrant, and facilitates memory consolidation

Ectothiorhodospira variabilis, sp. nov., an alkaliphilic and halophilic purple sulfur bacterium from soda lakes

During studies of moderately halophilic strains of Ectothiorhodospira from steppe soda lakes, we found a novel group of bacteria related to Ectothiorhodospira haloalkaliphila with salt optima at 50–80 g NaCl l”1. Phylogenetic analysis using 16S rRNA gene sequences of strains from soda lakes in Mongolia, Egypt and Siberia revealed separation of the group of new isolates from other Ectothiorhodospira species, including the closely related Ect. haloalkaliphila. DNA–DNA hybridization studies demonstrated that the new isolates form a homogeneous group at the species level, but at the same time are distinct from related species such as Ect. haloalkaliphila, Ect. vacuolata, Ect. shaposhnikovii and Ect. marina. The new isolates are considered to be strains of a novel species, for which the name Ectothiorhodospira variabilis sp. nov. is proposed, with the type strain WN22T (5VKM B-2479T 5DSM 21381T). Photosynthetic pigments of the novel species are bacteriochlorophyll a and carotenoids of the spirilloxanthin series with spirilloxanthin and derivatives thereof, together with small amounts of lycopene and rhodopin. Gas vesicles are formed by most of the strains, particularly in media containing yeast extract (0.5 g l”1) and acetate (0.5–2.0 g l”1). Sequence analysis of nifH (nitrogenase) and cbbL (RuBisCO) confirmed the assignment of the strains to the genus Ectothiorhodospira and in particular the close relationship to Ect. haloalkaliphila. The novel species Ect. variabilis is found in soda lakes separated by great geographical distances and is an alkaliphilic and halophilic bacterium that tolerates salt concentrations up to 150–200 g NaCl l”1

Phylogenetic Diversity and Antimicrobial Activities of Culturable Endophytic Actinobacteria Isolated from Different Egyptian Marine Sponges and Soft Corals

A cultivation-based approach was employed to isolate and compare the endophytic culturable actinobacterial diversity associated with different Egyptian marine sponges and soft corals. A total of 13 culturable actinobacteria isolates were obtained, five of which isolated from different sponges, two (AE27 and AE32) and three (AE29, AE41 and AE46) were isolated from Haliclona sp. and Callyspongia sp. collected from Sharm El-Sheikh and Hurghada, Egypt, respectively. Eight were isolated from different five soft corals, out of them two (AE2 and AE19), two (AE3 and AE15), two (AE20 and AE23), one (AE35) and one (AE13) were isolated from Rhytisma sp., Xenia sp., Lobularia sp., and Dendronephthya sinaiensis (collected from Sharm El-Sheikh, Egypt) and the Dendronephthya hemprichi (collected from Hurghada, Egypt), respectively. The 16S rRNA genes of the 13 actinobacteria isolates were amplified and sequenced (GenBank Accession numbers JF292923 – JF292930 and JF319146 – JF319150). A BLAST analysis revealed that the 13 actinobacteria isolates belonged to three known families and genera. Six strains isolated from all sponges and soft corals belonged to the genus Streptomyces (AE15, AE19, AE20 and AE35, isolated from soft corals; Xenia sp., Rhytisma sp., Lobularia sp., and Dendronephthya sinaiensis as well as AE29 and AE41, isolated from sponges; Callyspongia sp., respectively). Six strains (AE2, AE3 and AE23, isolated from soft corals; Rhytisma sp., Xenia sp. and Lobularia sp. as well as AE27, AE32 and AE46, isolated from sponges; Haliclona sp. and Callyspongia sp., respectively) belonged to the genus Nocardiopsis. Only one isolate (AE13) derived from Dendronephthya hemprichi was belonged to the genus Pseudonocardia. The phylogenetic analysis revealed that four culturable actinobacteria strains (AE2, AE27, AE32 and AE46) were more distantly related to other previously published Nocardiopsis dassonvillei. Screening for antimicrobial activity revealed that out of the 13 culturable actinobacteria isolates, only five (AE15, AE19, AE20, AE29 and AE41) belonged to the genus Streptomyces have anticandida or anti-positive Gram bacteria activity