Bacteria

About: Bacteria is a research topic. Over the lifetime, 23676 publications have been published within this topic receiving 715990 citations. The topic is also known as: eubacteria.

Marine diatom species harbour distinct bacterial communities

Abstract: Summary We examined bacterial dynamics in batch cultures of two axenic marine diatoms ( Thalassiosira rotula and Skeletonema costatum ). The axenic diatoms were inoculated with natural bacterial assemblages and monitored by 4,6-diamidino-2-phenolindole (DAPI) counts, denaturing gradient gel electrophoresis (DGGE) with subsequent analysis of excised, sequenced 16S rRNA gene fragments, and fluorescence in situ hybridization (FISH) with group-specific 16S rRNA oligonucleotide probes. Our results show that algal growth exhibited pronounced differences in axenic treatments and when bacteria were present. Bacterial abundance and community structure greatly depended on species, growth and physiological status of even closely related algae. Free-living and phytoplankton-associated bacteria were very different from each other and were dominated by distinct phylogenetic groups. The diatom-associated bacteria mainly belonged to the Flavobacteria ‐ Sphingobacteria group of the Bacteroidetes phylum whereas freeliving bacteria, which were rather similar in both cultures, comprised mainly of members of the Roseobacter group of a - Proteobacteria . Presence and disappearance of specific bacteria during algal growth indicated pronounced differences in environmental conditions over time and selection of bacteria highly adapted to the changing conditions. Tight interactions between marine bacteria and diatoms appear to be important for the decomposition of organic matter and nutrient cycling in the sea.

Production of soluble recombinant proteins in bacteria

Abstract: Production of recombinant proteins in bacteria is limited by the formation of cytoplasmic aggregates (inclusion bodies or “IBs”). This review summarizes what is known about why IBs form and ways of increasing the production of soluble protein in bacterial systems. The easiest way to lower IB formation is to reduce the growth temperature of the bacteria. IB formation is not directly correlatable with the production rate, nor with the size of the produced protein. The primary sequences of a few proteins that do not form IBs at higher production temperatures contain either a low content of proline residues or stretches of acidic amino acids. Metal ion binding may also lower the tendency to form IBs at growth temperatures above 30°C. Three aspects of protein synthesis in mammalian cells, compartmentation, interprotein interactions (sortases, foldases, unfoldases, and chaperonins), and post-translational modifications, have significant effects on the solubility of the proteins produced. Possibilities for mimicking these mechanisms in bacteria via secretion, cloning of mammalian foldases, and mutation of the post-translational modification systems of the host bacteria are discussed.

Tunicamycin, a new antibiotic. i

Abstract: Tunicamycin is a new antiviral antibiotic produced by Streptomyces lysosuperificus, nov. sp. The active substance in culture broth is purified by solvent extraction followed by chromatography on silicic acid. It has a mole- cular weight of about 870. The antibiotic is active against animal and plant viruses, Gram-positive bacteria, yeast and fungi. Tunicamycin is similar in some properties to a few known antibiotics but differs from them in certain special characteristics.