Search results for: Tryptose Phosphate Broth in Powder _ kg
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Caffeine and Theobromine.
Two components of cocoa powder, caffeine (1,3,7-trimethylxanthine) and theobromine (3,7-dimethylxanthine), were evaluated for their effect on growth of L. monocytogenes strain V7. Caffeine (0.5%) and theobromine (2.5%) were added singly or in combination to skim milk or a modified tryptose phosphate broth (MTPB), which were sterilized, inoculated to contain ca. 1 × 10 CFU L. monocytogenes /ml, and incubated at 30°C. Both compounds allowed some growth of the pathogen; however, longer lag phases occurred in samples with (6 to 9 h) rather than without (<3 h) caffeine. Generation times at 30°C ranged from 1.10 h (2.5% theobromine in broth) to 2.28 h (2.5% theobromine plus 0.5% caffeine in milk). Generation times were significantly (p<0.05) lengthened in the presence (2.17 h) rather than in the absence (1.2 h) of caffeine. Populations in samples without caffeine were more than ten times greater (8.57 log CFU/ml) than in samples with caffeine (7.21 log CFU/ml). Theobromine concentration (0 or 2.5%) and substrate (MTPB or skim milk) had only limited effects on growth of the pathogen. The change in pH of the medium was a function of the extent of growth of L. monocytogenes and the buffering capacity of the substrate. A smaller pH change (0.09 unit) occurred in the milk medium than in broth (0.48 unit) because of the minimal buffering capacity of the 0.2% tryptose solution. Samples with caffeine had a small decrease in pH (0.07 unit) because growth of L. monocytogenes was inhibited and thus acid production was minimal.Laura J Pearson, Elmer H Marth
2852 related Products with: Caffeine and Theobromine.
500 mg25 mg2.5 mg10 mg100ug25 mg 5 G50 ug 5 G100ul1 g96 wells (1 kit)
Related Pathways
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Stability of the F strain of Mycoplasma gallisepticum in various diluents at 4, 22, and 37 C.
The stability of the F strain of Mycoplasma gallisepticum was determined in reconstituted powdered skim milk, phosphate-buffered saline, tryptose phosphate broth, and distilled water at 4, 22, and 37 C. The culture was stable for up to 24 hr in all diluents at 4 and 22 C. At 37 C, the culture was stable up to 24 hr in phosphate-buffered saline, but there was a slight reduction of viability in tryptose phosphate broth at 8 and 24 hr, and the titer was reduced in skim milk at 24 hr. In distilled water, the culture was stable up to 4 hr at 37 C. A reduced titer was observed after 8 hr, and at 24 hr the culture was no longer viable.S H Kleven