also see Salmonella
Gram-negative rods widely distributed in lizards and snakes, and implicated in enteric, bone, and
joint infections in man.
Zentralbl Bakteriol Orig B. 1978 Jan;166(1):95-104.
[Arizona bacteria (salmonella subgenus III), a rarely identified cause of food infections (author's
[Article in German]
Toeller W, Wuthe HH, Rohde R.
A report is given of the infection, described under the clinical picture of enteritis, of a one-year
old Turkish child with Salmonella arizonae 61:k:1,5,7 (Arizona 26:29-30) which is largely adapted
to sheep. It appears that, outside of the USA reports have not been published on infections with
this species of Salmonella. Considering that reports on human infections with Salmonellae of the
subgenus III (Arizona bacteria) have rarely been published, it was decided to deal with these
Salmonellae in general, especially with their reservoirs, the clinical pathological pictures and the
problems associated with the bacteriological diagnosis which is made on the basis of the ready
splitting of lactose of numerous species of the Arizona group.
APPLIED AND ENVIRONMENTAL MICROBIOLOGY, May 1982, p. 1016-1019 Vol. 43, No. 5
Effect of Growth Conditions on Heat Resistance of Arizona
Bacteria Grown in a Chemostat
Western Regional Research Center, Science and Education Administration, U.S. Department of
Berkeley, California 94710
Received 21 September 1981/Accepted 26 January 1982
The effects of various growth conditions on the heat resistance of Arizona
bacteria grown in a continuous-culture device (chemostat) were studied. Using
either glucose, NH4CI, NaH2PO4, or MgCl2 as the rate-limiting nutrient, it was
found that the heat resistance, in all cases, depended on the dilution rate and,
hence, growth rate of the culture. Cells grown at high dilution rates were less heat
resistant than those grown at low dilution rates. If, however, the dilution rate was
maintained at a constant rate, the higher the growth temperature, the more heat
resistant were the cells. Also at any given dilution rate, the cells were most heat
resistant when grown at a near neutral pH. Most survival curves were biphasic in
shape, indicating the presence in the population of two fractions of cells, one
fraction being more resistant than the other. The size of the more heat-resistant
fraction varied from almost 100% in very slow-growing cultures to practically 0%
in cultures grown at a dilution rate of 0.67 h-1.
The heat resistance of bacterial cells is affected
by cultural conditions such as temperature,
pH, medium composition, and rate and phase of
growth (2, 6, 7, 9). During the growth of a batch
culture, some of these factors, such as pH and
growth rate, continually change; furthermore,
some factors cannot be varied without affecting
others. For example, studying the effect of
growth temperature on heat resistance would be
complicated by the fact that temperature could
not be altered without simultaneously affecting
the rate of growth. However, by the use of a
continuous-culture device known as a chemostat
(3, 8), growth rates can be maintained constant
by simply controlling the rate of addition of a
growth-limiting nutrient while environmental
factors such as temperature or pH can be varied.
The purpose of the present study, therefore,
was to determine how heat resistance ofArizona
bacteria grown in a chemostat is affected by the
following variables: (i) dilution rate (D); (ii) the
kind of substrate serving as the growth-limiting
nutrient; (iii) the pH of the culture; and (iv) the
temperature of growth.