The Journal of Medical Microbiology, Vol 38, Issue 3 227-234, Copyright © 1993 by Society for General Microbiology
Isolation and purification of Aeromonas sobria cytotonic enterotoxin and beta-haemolysin
P. J. Gosling, P. C. Turnbull, N. F. Lightfoot, J. V. Pether and R. J. Lewis
Public Health Laboratory, Musgrove Park Hospital, Taunton, Somerset.
Aeromonas sp., grown in tryptone soya broth supplemented with yeast
extract, 0.6%, pH 7.5, and incubated with agitation at 100 oscillations/min
for 15 h at 37 degrees C produced optimal amounts of beta-haemolysin and
cytotonic enterotoxin. More prolonged incubation resulted in the loss of
enterotoxic activity and anion exchange chromatographic analysis indicated
the presence of a moiety capable of breaking down the toxin. Anion exchange
fast protein liquid chromatography resulted in a single peak of haemolytic
activity and two peaks with enterotoxic activity. The cytotonic enterotoxin
was purified from the fraction most active in the infant mouse assay; the
second peak, which did not cross-react immunologically, may represent a
second cytotonic enterotoxin. Neither peak was observed in the
chromatographic fractions of filtrates from strains devoid of activity in
the infant mouse assay. Purified enterotoxin, estimated to have a mol. wt
of 15 kDa by SDS-PAGE, caused fluid accumulation in the infant mouse assay,
was non-haemolytic to rabbit erythrocytes, caused an increase in cAMP
activity in tissue culture cells and did not cross-react immunologically
with components of cholera toxin or the whole toxin. Purified
beta-haemolysin had an estimated mol. wt of 55 kDa, lysed rabbit
erythrocytes and did not cause fluid accumulation in the infant mouse test.
