Functional analysis of the invariant residue G791 of Escherichia coli 16S rRNA.

The nucleotide at position 791(G791) of E. coli 16S rRNA was previously identified as an invariant residue for ribosomal function. In order to characterize the functional role of G791, base substitutions were introduced at this position, and mutant ribosomes were analyzed with regard to their protein synthesis ability, via the use of a specialized ribosome system.

Heterogeneous rRNAs are differentially expressed during the morphological development of Streptomyces coelicolor.

It is generally assumed that all mature rRNA molecules assembled into ribosomes within a single cell are identical. However, sequence analysis of Streptomyces coelicolor genome revealed that it harbors six copies of divergent rRNA operons that may express and constitute three and five different kinds of small subunit (SSU) and large subunit (LSU) rRNA molecules, respectively, in a single cell. Phylogenetic analyses of the LSU rRNA genes and the internal transcribed spacer between SSU and LSU genes indicated that the LSU gene of rrnA and rrnE operons might be the result of interspecies recombination between rRNA genes in closely related streptomycetes.

Removal of antibiotics by coagulation and granular activated carbon filtration.

Treatment of seven tetracycline classes of antibiotic (TAs) from raw waters (synthetic and river) was evaluated using coagulation and granular activated carbon (GAC) filtration in this study. Both coagulation and GAC filtration were effective for removal of TAs, and the removal efficiency depended on the type of TAs. GAC filtration was relatively more effective for removal of tetracycline (TC), doxycycline-hyclate (DXC), and chlortetracycline-HCl (CTC), which were difficult to remove by coagulation.

Determination of antibiotic compounds in water by on-line SPE-LC/MSD.

This study attempts to provide an improved approach for the analysis of antibiotics, which normally exist at low concentration in complex matrices such as receiving streams of wastewater treatment plant discharge. The analytical method developed in this study combines an existing pretreatment technique of solid-phase extraction (SPE) with liquid chromatography mass spectrometry (LC/MSD) through on-line connection. The on-line connection suppressed the target loss by keeping the cartridge from drying, which resulted in improvement of the recovery and saving of the analytical time.

Photobacterium ganghwense sp. nov., a halophilic bacterium isolated from sea water.

A marine bacterial strain, designated FR1311T, was isolated from a sea-water sample from Ganghwa Island, South Korea. Cells were Gram-negative, facultatively anaerobic, catalase- and oxidase-positive, motile, oval or rod-shaped and halophilic (optimum sea-salt concentration for growth of 5-6 %). Phylogenetic analysis of its 16S rRNA gene sequence revealed that it represented a distinct line of descent within the genus Photobacterium.

Clostridium ganghwense sp. nov., isolated from tidal flat sediment.

A Gram-negative, strictly anaerobic, halophilic, motile, sporulating and rod-shaped bacterium, designated strain HY-42-06T, was isolated from tidal flat sediment from Ganghwa Island in South Korea. The isolate produced glycerol, ethanol and CO2 as fermentation end-products from glucose. Strain HY-42-06T grew optimally at 35 degrees C, pH 7.

Enterobactin: an archetype for microbial iron transport.

Bacteria have aggressive acquisition processes for iron, an essential nutrient. Siderophores are small iron chelators that facilitate cellular iron transport. The siderophore enterobactin is a triscatechol derivative of a cyclic triserine lactone.

Corynebactin and a serine trilactone based analogue: chirality and molecular modeling of ferric complexes.

Because the hydrolysis of ferric ion makes it very insoluble in aerobic, near neutral pH environments, most species of bacteria produce siderophores to acquire iron, an essential nutrient. The chirality of the ferric siderophore complex plays an important role in cell recognition, uptake, and utilization. Corynebactin, isolated from Gram-positive bacteria, is structurally similar to enterobactin, a well-known siderophore first isolated from Gram-negative bacteria, but contains L-threonine instead of L-serine in the trilactone backbone.

Corynebactin and enterobactin: related siderophores of opposite chirality.

Most species of bacteria employ siderophores to acquire iron. The chirality of the ferric siderophore complex plays an important role in cell recognition, uptake, and utilization. Corynebactin, isolated from Gram-positive bacteria, is structurally similar to enterobactin, a well known siderophore isolated from Gram-negative bacteria, but contains L-theronine instead of L-serine in the trilactone backbone.

Enhanced anaerobic biotransformation of carbon tetrachloride in the presence of reduced iron oxides.

Rates of anaerobic transformation of carbon tetrachloride (CT) by the facultative anaerobe Shewanella putrefaciens 200 were increased by the presence of Fe(III)-containing minerals. In batch reactors with amorphous, Fe(III)-hydroxide and S. putrefaciens, CT transformation rates could be modeled by a first-order expression in which the pseudo-first-order rate constant was linearly proportional to the initial concentration of Fe(III)-oxide.