Sj. Assinder et al., AN IN-VITRO SYSTEM FOR THE ANALYSIS OF CHANGES IN-DEPTH DISTRIBUTION OF DIFFUSATES IN BACTERIAL FILMS, Caries research, 32(4), 1998, pp. 255-261
No suitable technique exists which allows simultaneous analysis of tim
e-and depth-dependent concentrations of all components of interest in
single samples of intercellular fluid from dental plaque biofilms. We
have developed an in vitro model which allows detailed study of these
interactions by analysis of intercellular fluid and pH measurement at
the film base. Compact, defined-depth films of Streptococcus mutans we
re formed in a micrometer-controlled, variable-depth well and bathed i
n synthetic saliva. Films exposed to synthetic saliva containing gluco
se for 2 min followed by clearance with glucose-free synthetic saliva
gave typical 'Stephan-type' pH profiles. Intercellular fluid isolated
from successive 200-mu m-thick sections of 600-mu m-deep films was ana
lysed by ion chromatography. A concentration gradient of lactate, fall
ing with depth, was measured. The experimental system described here,
the first of its type to be described, can easily be used to analyse p
H changes and the depth-dependent distribution of diffusates in a mode
l bacterial film. Although this bacterial film is far removed from a n
atural biofilm, the apparatus has potential for the study of grown bio
films and is an important advance towards position-dependence analysis
of diffusates in biofilms.