Ml. Stecchini et al., INFLUENCE OF STRUCTURAL-PROPERTIES AND KINETIC CONSTRAINTS ON BACILLUS-CEREUS GROWTH, Applied and environmental microbiology, 64(3), 1998, pp. 1075-1078
The influence of structural properties and kinetic constraints on the
behavior of Bacillus cereus was investigated on agar media, Dimensiona
l criteria were used to study the growth in bacterial colonies, The ar
chitecture of the agar gel as modified by the agar content was found t
o influence the colony size, and smaller colonies were observed on med
ia containing 50 to 70 g of agar liter(-1). Except at low nutrient lev
els, colonies responded to nutrient gradients by decreasing in size th
e farther away they were from the nutrient source, and the decrease in
colony size was influenced by the agar content. The diffusivities of
glucose and a protein (insulin like growth factor) were not affected b
y the gel architecture, suggesting that other factors, such as mechani
cal factors, could influence microbial growth in the agar systems used
. Increasing the viscosity of the liquid phase of the agar media by ad
ding polyvinylpyrrolidone resulted in a reduction in colony size. When
the agar concentration was increased, the colony areas were not influ
enced by the viscosity of the system.