Study on the effect of thiamine on the metabolism of yeast by intrinsic fluorescence.

Thiamine in living human bodies exists mainly as diphosphate, which works as a co-enzyme of the sugar metabolism system (active vitamin B1). Thiamine deficiency brings many clinically significant problems, such as dysphoria, quadriplegia and dyspepsia. Intrinsic fluorescence has an advantage over the extrinsic fluorescence of an unperturbed environment during investigation, especially in complex systems such as biological cells and tissues. Cellular fluorescence provides a sensitive index of the functional state of a living cell (1). Different amounts of thiamine were added to culture medium and the fluorescence of tryptophan and NADH from yeast was determined. When the thiamine concentration was greater than 0-0.16 microg/mL, the intensity of tryptophan fluorescence increased linearly, whereas the NADH fluorescence decreased. When the thiamine concentration was above 0.24 microg/mL, the fluorescence of tryptophan and NADH was almost unchanged. We concluded that low thiamine concentration in culture medium had a large effect on the growth of Saccharomyces cerevisiae and possible reasons are discussed.