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Rapid microbiochemical identification of Corynebacterium diphtheriae and other medically important corynebacteria.

A rapid biochemical method based on the fermentation of carbohydrates, the hydrolysis of urea, and the reduction of nitrate was used to identify Corynebacterium diphtheriae, C. ulcerans, C. pseudodiphtheriticum, C. haemolyticum, C. pseudotuberculosis, C. pyogenes, C. ovis, the Centers for Disease Control JK group, and Rhodococcus (Corynebacterium) equi. With this procedure identification was confirmed for 133 stock cultures and clinical isolates of corynebacteria. Most were identified within 1 h and all were identified within 4 h after inoculation into the test substrates.

Bacteriological Techniques↗

Surviving the acid test: responses of gram-positive bacteria to low pH.

Gram-positive bacteria possess a myriad of acid resistance systems that can help them to overcome the challenge posed by different acidic environments. In this review the most common mechanisms are described: i.e., the use of proton pumps, the protection or repair of macromolecules, cell membrane changes, production of alkali, induction of pathways by transcriptional regulators, alteration of metabolism, and the role of cell density and cell signaling. We also discuss the responses of Listeria monocytogenes, Rhodococcus, Mycobacterium, Clostridium perfringens, Staphylococcus aureus, Bacillus cereus, oral streptococci, and lactic acid bacteria to acidic environments and outline ways in which this knowledge has been or may be used to either aid or prevent bacterial survival in low-pH environments.

Bacillus cereus↗

Purification and characterization of CeqI restriction endonuclease.

CeqI, a type II restriction endonuclease, an isoschizomer of EcoRV was purified to apparent homogeneity by a combination of salt precipitation, ion exchange, dye affinity and hydrophobic interaction chromatographies. The crude enzyme was present in the form of large aggregates that could be pelleted by high speed centrifugation. The enzyme was not associated with cellular membranes, though non-ionic detergents lowered the apparent size of the aggregates. The purified enzyme also showed a tendency to form large molecular mass (66-600 kDa) complexes under physiological conditions, in the absence of cleavable DNA. The enzyme formed smaller complexes in the presence of DNA and non-ionic detergents and dissociated into subunits (and undergoes reversible loss of activity) in the presence of high concentrations of salts. According to SDS gel electrophoresis and sedimentation analysis the molecular mass of the monomer 32 +/- 2 kDa. The enzyme had a rather broad PH optimum, extending into the alkaline range and lost specificity and activity in buffers below pH 6.

Base Sequence↗

Corynebacterium pseudotuberculosis exotoxin: fatal hemolytic anemia induced in gnotobiotic neonatal small ruminants by parenteral administration of preparations containing exotoxin.

Inoculation of live Corynebacterium pseudotuberculosis, culture supernatant, ammonium sulfate-fractionated crude exotoxin, or chromatographically purified exotoxin preparations into gnotobiotic small ruminants (n = 13) caused death of the ruminants within 48 hours. Characteristic changes observed in animals living greater than or equal to 2 hours after inoculation included hemorrhage and edema at the site of injection, severe hemolytic anemia and hemoglobinuria, dark red fluid in body cavities, lung edema, and icterus. The crude exotoxin preparation caused a syndrome of acute shock in 2 lambs that died within 15 minutes after inoculation. Clinical and pathologic responses of animals inoculated with culture supernatant and purified toxin were similar. Histopathologic evidence indicated that the exotoxin caused necrotic changes in the proximal convoluted tubules of the kidneys. Inoculation with live organisms caused multiple foci of suppurative inflammation in skeletal muscle and adjacent adipose tissue, whereas such changes were not observed in animals administered exotoxin preparations. Although C pseudotuberculosis exotoxin induced a hemolytic anemia in the experimental animals, it did not lead to in vitro lysis of ovine, caprine, or bovine erythrocytes, unless they had been sensitized with Rhodococcus (Corynebacterium) equi filtrate. The toxic sphingomyelin-specific phospholipase D from C pseudotuberculosis had a molecular weight of 31,000 daltons and an isoelectric point of approximately 9.6. The elution profile of exotoxin on a carboxymethyl Sephadex column was studied and the majority of the enzymatic activity was eluted by a NaCl gradient (0.25M to 0.7M) with a maximum at 0.35M NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia, Hemolytic↗