Microbiological assays thiamin status

Methylcobalamin, 516 5-Melhyl-cytosine, deaminatitm, 894 Methylglyoxal, 836 Methylmalonic acid (MMA), 434, 522 MethylmalcHiy. CoA, 434, 517, 518 Mevalonic acid, 327, 328 Mg-ATP complex, 795-796 Micelles, 25,27-29 MLcroaulophagy, 444 Microbiological assays, 508 biotin determination, 541 folate status by, 509 thiamin status, 607 Microcytic anemia, 5H Microsomal ethanol-oxidizing system, 247 Microvilli, 58 Milk... 

Thiamin status has been assessed by direct tests involving the measurement of thiamin levels in the blood or urine. The vitamin can be assayed by the thiochrome method or by microbiological assays. The disadvantage of these methods is that thiamin levels in normal individuals can vary greatly. The test organism used for microbiological assays may be Lactobacillus viridescens or Lactobacillus fermenti. 

Historically, assessment of thiamine status was by animal bioassay (the correction of bradycardia in thiamine-deficient rats) and later by microbiological assays using the fungus Phycomyces hlakesleeanus, yeast fermentation, or bacteria of the Staphylococcus, Streptococcus, or Lactobacillus species. Some bacterial microbiological assays are still in use in the food industry. Early chemical methods were often based upon the production of a fluorophore, thiochrome, when thiamine is oxidized with ferricyanide in alkaline solution, a property that is used in some modern chromatographic methods. 

Levels of excreted thiamine in urine have been measured using various techniques, including the trichrome method (based on the oxidation of thiamine) (Bessey et al. 1952), microbiological assay using Lactobacillus viridescens (Sauberlich et al. 1979), and high performance liquid chromatography (HPLC) (Roser et al. 1978). Urinary assessment of thiamine status presents several... 

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