A Selective Medium for the Isolation and Enumeration of Oral and Fecal Lactobacilli

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.

Epidemiology of root surface caries in patients treated for periodontal diseases

“…Saliva samples were homogenized by ultrasonic dispersion for 20 s at 0°C using a Kontes sonifier K-881440 provided with a microtip. The suspensions were serially diluted 10fold and plated onto TYCSB agar (16) and Rogosa SI agar (17). TYCSB served to enumerate S, mutans.…”

Analysis of treatment effects on the microbial ecology of the human intestine

“…Bifidobacteria were enumerated using BIM-25 (Muñoa & Pares, 1988;Lapierre et al, 1992;Rada et al, 1999), which is a reinforced clostridial agar base containing polymixin B, tetrazolium red, iodoacetate, kanamycin, and naladixic acid (Sigma-Aldrich, St Louis, MO). Lactobacilli were enumerated using LBS Agar (Difco) plus 200 mL L À1 tomato juice from concentrate (Campbell Soup, Camden, NJ) (Rogosa et al, 1951;Sabine & Vaselekos, 1965). Organisms in the Bacteroides fragilis group were enumerated with Bacteroides Bile Esculin Agar (BBE; Difco).…”

Chararacteristics of Vagococcus salmoninarum isolated from diseased salmonid fish

“…Growth was determined in the presence of: 3.0, 4.0 and 6.5% w/v NaCl (Phillips and Nash 1985), &O.l% NaCI, post-autoclaving (concentration determined by ferricyanide method, Clesceri et al 1989); pH 9.6 by Clarke's method (Cowan 1974); crystal violet at 0.002 and 0.004 g I-' in BAB; bile salts in crystal violet-free MacConkey agar (Oxoid, CM7) and thiosulphate citrate bile salts sucrose (TCBS) medium (Oxoid, CM333); and on acetate agar (Oxoid, CM627) as described by Rogosa et al (1951).…”