Abstract: A method for preparing, and increasing the flavor molecules in, a yeast extract and a use of the yeast extract are provided. The method includes culturing a yeast strain of the Kluyveromyces marxianus species in a yeast culture medium under predetermined conditions in order to increase the diversity and amounts of the sweetness peptides in the yeast culture, thereby providing the yeast extract with strong sweetness and/or umami so that the yeast extract can be used as a food seasoning.

Abstract: The present invention provides a method for increasing the metabolic rate of recombinant microorganism growth under an anaerobic environment, wherein a recombinant strain is placed under an anaerobic environment and cultured under a culture condition, wherein the culture condition includes a potential difference and a nitrogen source, but not includes an organic carbon source. According to the method disclosed by the present invention, the recombinant strain can perform anaerobic respiration and metabolic reaction in an anaerobic environment, and can grow stably and rapidly.