SUMMARY: An improved growth medium for lactobacilli is described. It supports good growth of lactobacilli generally and also is particularly useful for a number of fastidious strains which grow only poorly in other general media. In addition, tomato juice, a highly variable material, is not required. In a slightly modified form, it can also be used as a basal medium for fermentation tests.

No abstract

absorb toxic materials that may inhibit germination. One aliquot was plated unheated, another was heated at 95 C for 10 minutes, the third was inoculated into a 10-6 dilution of furfural for 30 minutes, and the fourth was treated with furfural but also subsequently received the heat treatment. The facultative thermophiles were incubated at 37 C and 55 C and the obligate thermophiles at 55 C for 48 hours. Counts made at 24 hours, however, did not materially increase in 48 hours. Table 1 gives the results of these experiments. It will be noted that in all cases treatment with furfural has given viable spore counts comparable to those obtained following heat treatment, whereas a combination of the two gave little additional increase. Incubation at 37 C resulted in lower total counts in the same time interval but gave analogous results with incubation at 55 C. Table 2 shows the effect of incorporation of the furfural into the plating medium. At high concentrations an inhibition of both germination and growth occurs, but at low concentrations a marked increase in viable count is noted. The mode of action of furfural is unknown, but it may act as a reducing agent. However, when thioglycolate is used at 0.1 per cent or at a 10-6 dilution, the activation is not noted. Furfural has no effect on the growth of vegetative cells except at high concentrations (table 2, strain no. 1503) demonstrating that the action is probably solely upon germination. The possibility that furfural acts in removing toxic materials from the medium is under investigation.