Genes involved in hydrogen and sulfur metabolism in phototrophic sulfur bacteria

The dsr genes and the hydSL operon are present as separate entities in phototrophic sulfur oxidizers of the genera Allochromatium, Marichromatium, Thiocapsa and Thiocystis and are organized similarly as in Allochromatium vinosum and Thiocapsa roseopersicina, respectively. The dsrA gene, encoding the alpha subunit of 'reverse' siroheme sulfite reductase, is also present in two species of green sulfur bacteria pointing to an important and universal role of this enzyme and probably other proteins encoded in the dsr locus in the oxidation of stored sulfur by phototrophic bacteria. The hupSL genes are uniformly present in the members of the Chromatiaceae family tested. The two genes between hydS and hydL encode a membrane-bound b-type cytochrome and a soluble iron-sulfur protein, respectively, resembling subunits of heterodisulfide reductase from methanogenic archaea. These genes are similar but not identical to dsrM and dsrK, indicating that the derived proteins have distinct functions, the former in hydrogen metabolism and the latter in oxidative sulfur metabolism.     

Photo-autotrophic growth of Thiocapsa roseopersicina on dimethyl sulfide

Abstract: The purple sulfur bacterium Thiocapsa roseopersicina was examined for photo-autotrophic growth on dimethyl sulfide (DMS). The maximum specific growth rate μ _max (0.068 h⁻¹), saturation constant K _s (38 μm l⁻¹), and yield (5.24 mg protein mmol⁻¹ DMS) were determined in chemostat experiments. Dimethyl sulfoxide was the only product of DMS oxidation. Batch experiments revealed the simultaneous oxidation of DMS and hydrogen sulfide.     

Community Structure of Macrobenthic Invertebrates in Sandy Beaches of the Jordan Gulf of Aqaba,Red Sea

Six sandy beach stations along the Jordan Gulf of Aqaba were selected for macrofaunal examination during November 1980. Fifteen core samples (0.01 m² to a depth of 10–15 cm) were taken at each station; five at the high tide line, five at the low tide line, and five midway. Twenty-two taxa were encountered from all stations. Polychaetes were the most diverse group with seven taxa, followed by molluscs and crustaceans with six and five taxa respectively. Animal diversity, using the Shannon-Wiener Index, was generally low. Based on the biological index value of McCLOSKEY (1970), seven taxa were considered the community dominants. These are: the polychaetes, Glycera tesselata, Pisione remota, Saccocirrus sp., and Perinereis nuntia; the isopod Eurydice arabica; a nemertean and an oligochaete.