Production and partial characterization of a Vibrio fluvialis cytotoxin

Conditions are described for the production of an extracellular cytotoxin or CHO cell-killing factor by Vibrio fluvialis, a recently recognized enteric pathogen. The cell-killing factor was ammonium sulfate precipitable, heat labile, and inactivated by proteases, and had an isoelectric point (estimated by sucrose density gradient electrofocusing) and an apparent molecular weight (estimated by gel filtration) of ca. 4.8 and 12,200, respectively. The culture supernatant fluids also possessed hemolytic and phospholipase A2 activities; however, they were separable from cell-killing factor activity by gel filtration. The substance(s) possessing the hemolytic and phospholipase activities coeluted when fractionated by gel filtration with Sephacryl S-200 (apparent molecular weight of ca. 34,500) and had isoelectric points of ca. 4.4 and 4.5, respectively.