Characteristics of bacterium GB-2, a presumptive Cytophaga species with novel immunoregulatory properties

William R. Usinger, George C. Clark, Ellen Gottschalk, Stanley Holt, Robert I. Mishell

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


A Gram-negative, psychrophilic bacterium, designated GB-2, was isolated from fetal calf serum and analyzed for its morphological, physiological, and biochemical characteristics. Gliding motility, sensitivity to actinomycin D, the presence of the pigment flexirubin and cytochrome c, growth on a variety of carbohydrates, the production of acid fermentation products, and a 34.9 mol% guanine+cytosine (G+C) content of bacterial DNA indicate GB-2 to be a member either of the genera Cytophaga or Flexibacter. Growth of GB-2 was optimized in a simple defined medium to facilitate isolation and characterization of bacterial products. Liquid growth of GB-2 resulted in the release of significant quantities of a macromolecule free of both endotoxin and protein into the growth supernatant, which activated the proliferation of murine lymphocytes. The relationship between this bacterium and its end-products to other species of the Cytophaga/Flexibacter group is discussed.

Original languageEnglish (US)
Pages (from-to)203-207
Number of pages5
JournalCurrent Microbiology
Issue number4
StatePublished - Jul 1985

ASJC Scopus subject areas

  • Microbiology
  • Applied Microbiology and Biotechnology


Dive into the research topics of 'Characteristics of bacterium GB-2, a presumptive Cytophaga species with novel immunoregulatory properties'. Together they form a unique fingerprint.

Cite this