Effects of Cultural Conditions on the Synthesis of Salmonella Toxin

Abstract

The influence of culture age, pH, aeration, and temperature on Salmonella toxin production was investigated using fermentor cultures containing casamino acids‐yeast extract as a growth medium. About 75% or more of total Salmonella toxin was synthesized and released when the cultures were harvested during stationary phase of growth. Increased production and release of the toxin was also observed when the cultures were regulated at pH 6.0, 7. 0, or under alkaline control. The optimal temperature for the synthesis of Salmonella toxin was at 37°C; increased aeration of the cultures (500 rpm) appeared to enhance Samonella toxin production.

Enterotoxin and cytotoxin production by Salmonella enteritidis strains isolated from gastroenteritis outbreaks

“…In addition to the discoi-er!-of the enterotoxin, another heat-stable toxic substance produced by S~iliii, enteritidis and Salni. [yphzrnuviuin has been reported (Koupal and Deibel 1973 ;Koo and Peterson 1982 ;Reitmeyer et 01. 1986 ;Ashkenazi et 01.…”

“…[yphzrnuviuin has been reported (Koupal and Deibel 1973 ;Koo and Peterson 1982 ;Reitmeyer et 01. 1986 ;Ashkenazi et 01.…”

“…Culturcs \\ere grov 11 in 13 ml of Casamino acid-yeast extract (CAYE) medium (Koo and Peterson 1982) at 37°C with shaking (200 rev min-I) for 20 h. The culture was then centrifuged at 10000 rev min-' for 8 min at 4°C. The cell pellet was washed once with 5 ml of PBS (8 g 1-' NaCl, 0.2 g 1-' KCl, 1.44 g 1 ' Na2HPOJ, 0.24 g 1-' KH,P04, pH 7.4), centrifuged and resuspended in 3 ml of PBS.…”

“…A protein synthesis assay based on [3H]-leucine incorporation was performed according to Koo and Peterson (1982) with some modifications. Monolayers of CHO cells were established by dispensing lo5 cells ml-' to each of a 24-well microtitre dish and allowing incubation for 18 h in a CO, incubator.…”