Permeabilizing action of polyethyleneimine on Salmonella typhimurium involves disruption of the outer membrane and interactions with lipopolysaccharide

Article Abstract:

The effect of polyethyleneimine (PEI), a polycationic polymer substance used as a flocculating agent and for immobilizing enzymes, on the ultrastructure of Salmonella typhimurium was studied. A great number of changes in the outer membrane of PEI-treated and thin-sectioned bacteria were seen by electron microscopy. Vesicular structures were observed on the surface of the outer membrane but there was no liberation of the membrane or its fragments. PEI was also observed to reduce the solubility of rough-type lipopolysaccharides (LPS) of the chemotypes Rb2 and Re but it had only a small effect on the abnormally cationic Rb2-type pmrA mutant LPS.

Gram-negative bacteria, Endotoxins, Bacterial cell walls, Salmonella typhimurium

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Bidirectional usage of ferulate by the acetogen Peptostreptococcus productus U-1: CO2 and aromatic acrylate groups as competing electron acceptors

Article Abstract:

The aromatic acrylate oxidoreductase system can be utilized by the acetogen Peptostreptococcus productus U-1 as a sole, energy-conserving and terminal electron-accepting process. However, the acetogen cannot prevent simultaneously using the acetyl-CoA pathway during O-methyl-dependent growth, despite its being bioenergetically less favorable. The use of acrylate group reduction for conserving O-methyl-derived energy is also affected by the availability of extracellular CO2.

Carbon dioxide, Electron donor-acceptor complexes, Acrylates

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Crystalline surface protein of Peptostreptococcus anaerobius

Article Abstract:

The surface of the pathogen Peptostreptococcus anaerobius contains a crystalline surface protein layer that is observable after freeze-etching treatment. These structures exhibit a periodic pattern when seen through negative staining. The surface protein is readily extractable by formic acid and exists as a band of 78 kDa protein. They are also evident when the cells are biotynilated and treated with extravidin. No such structures could be found on P. magnus and P. micros.

Streptococcus, Membrane proteins

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