Abstract
Betaine structural analogs are compounds characterized by the presence of positive and negative charges in a single molecule and have been reported to have physiological properties, such as anti-inflammatory activities. In this study, we performed a metabolomic analysis of metabolite composition changes during the fermentation of Neopyropia yezoensis, an edible red alga, with Aspergillus oryzae for 72 h. The results indicated that three specific betaine structural analogs (betaine, stachydrine, and carnitine) exhibited significant changes in production by the end of the 72 h fermentation period. Time-course analysis suggested that betaine was generated from the precursor choline at 12-24 h during the late stage of fungal growth, while stachydrine was generated from the precursor-related compound glutamic acid at 48-72 h during the sporulation stage. However, the contribution of the precursor lysine to the increased production of carnitine during the 12-72 h period was unclear. This study provides useful information on the efficient production of betaine structural analogs by the fungal fermentation of seaweed as well as various other food materials.