Sl. Walker et al., ADENYLATES AND ADENYLATE-ENERGY CHARGE IN SUBMERGED AND PLANKTONIC CULTURES OF SALMONELLA-ENTERITIDIS AND SALMONELLA-TYPHIMURIUM, International journal of food microbiology, 44(1-2), 1998, pp. 107-113
Adenine nucleotide values and adenylate energy charge (AEC) were measu
red during the growth of Salmonella enteritidis and Salmonella typhimu
rium as submerged colonies in agarose gel and gelatin gel, and as plan
ktonic cells in broth. Growth in all three systems showed similar tren
ds with a ten-fold decrease in total adenylate pool during exponential
growth, before attaining a fairly stable value throughout stationary
phase. AEC values were generally low, (approximate to 0.66), but did r
ise slightly during stationary phase. The large proportion of dead cel
ls during early exponential phase may have contributed to the adenosin
e diphosphate and adenosine monophosphate pools, through cell lysis or
excretion, and it. is suggested that this was likely to account for t
he low values of AEC. In agarose and gelatin gelled cultures the perce
ntage of adenosine triphosphate (ATP) in relation to the total adenyla
tes showed random fluctuations. This was contrary to the broth culture
where percentage ATP was highest after 12 h and the data formed a smo
oth curve. These data demonstrated that considerable physiological het
erogeneity exists within a colony of bacteria growing in a gel matrix
and by analogy a food material also, and that AEC is a poor indicator
of cell viability in such systems. (C) 1998 Elsevier Science B.V. All
rights reserved.