Effect of reduced water activity on vegetative growth of cells and on germination of endospores of Sporolactobacillus.
Growth of vegetative cells and germination of endospores of Sporolactobacillus at reduced water activity (aw) values were studied with NaCl and glycerol as humectants, and compared with Bacillus cereus and Clostridium sporogenes. With NaCl the highest aw for complete inhibition of both growth of vegetative cells and germinated spores of Sporolactobacillus was 0.955. With glycerol, growth of vegetative cells was completely inhibited at 0.905 as compared to 0.880 for vegetative growth resulting from germinated endospores. The mechanism of this phenomenon cannot be explained yet. NaCl appeared to have a toxic effect, in addition to inhibition by reduced aw per se.
Combined effect of water activity, pH and temperature on the growth of Clostridium botulinum from spore and vegetative cell inocula.
SUMMARY 
The initiation of vegetative growth by spores in Reinforced Clostridial Medium (RCM) adjusted to different water activities (aw) by the addition of NaCl or glycerol does not depend solely on the aw of the medium; minimum aw at which spores of Cl. botulinum types A, B and E could initiate growth were higher in the media containing NaCl. The minimum aw at which vegetative cell inocula could grow were similar to those at which spore inocula could initiate growth. The combined effect of lowering the pH and aw of the medium was to increase the minimum at which spores of types A and E could germinate and also increase the minimum at which spore and vegetative cell inocula of Cl. botulinum types A, B and E could initiate growth.
Lactobacilli in milk used for commercial cheesemaking
Summary The numbers of lactobacilli, including pediococci and some leuconostocs, in raw and heat treated milks at twenty-six cheese factories in different parts of the country were determined over a period of 12 months, by plating on acetate agar. Counts in the raw milks varied from < 1 to > 100000/ml, but were usually within the range 100 to 10000/ml. Widely different times and temperatures of heat treatment were in use at the different creameries, some of which destroyed most of the lactobacilli present, whilst others had less effect. Post heat treatment re-infection of the milk in the vat with lactobacilli usually occurred.