Effect of Tween 80 on incubation period of Lactobacillus case assay of serum folate
نویسنده
چکیده
The Lactobacillus casei response to folate is normally estimated by measuring the culture turbidity after 16 to 20 hours' incubation. Streeter and O'Neill (1969) found that cultures containing serum grew more rapidly than similar cultures containing folic acid (PteGlu) unless grown into the stationary phase (44 hours). Others, however, have reported comparable results from 20and 44-hour assays (Slade et al., 1974; Tennant et al., 1974). Eichner and Dickson (1974) obtained similar results to Streeter and O'Neill (1969) when using BBL folic acid assay PGA broth but not with Difco's Bacto-folic acid casei medium. The overall pattern of results is similar to that expected if free fatty acids were present in the assay systems of some workers. Free fatty acids inhibit the growth of L. casei (Williams and Fieger, 1946) unless adsorbed by albumin (Williams and Fieger, 1949) or a suitable non-ionic detergent (Davis and Dubos, 1947; Williams et al., 1947).
منابع مشابه
Effect of Tween 80 on incubation period of Lactobacillus casei assay of serum folate.
Contamination of folic acid assay medium with oleate led to a lag phase when Lactobacillus casei cultures were grown on folic acid but not when whole serum provided the folate source. This led to high assay values when using 20-hour incubation periods but satisfactory results were obtained after 48 hours' incubation. The addition of Tween 80 to the medium eliminated the lag phase and the assay ...
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