Abstract
Fukuyama pot vinegar is known as traditional Japanese rice vinegar. In the fermentation process of Fukuyama pot vinegar, fungi, yeast, lactic acid bacteria and acetic acid bacteria are involved. During this process, three types of fermentation, namely saccharification, anaerobic alcohol fermentation and aerobic acetic acid fermentation proceed autonomously, sequentially and partly in parallel. This is one of the most primitive fermentation process developed in East Asia and is analogous to carbohydrate metabolism occurred in nature. In order to elucidate inter-species interactions of microbes in this process, we isolated microbes from the brewing samples of the Fukuyama pot vinegar process and investigated the biofilm formation of lactic acid bacteria and yeasts or lactic acid and acetic acid bacteria under co-culture conditions. In the result, we found a unique mixed-species biofilm formation by lactic acid bacteria and yeasts on solid-liquid interface in a bottom of culturing vessel and also found a significant increase of acetic acid bacteria biofilm (pellicle) on liquid surface of culture broth in the co-existence of lactic acid bacteria. In further studies, we realized that the co-existent system of these three microbes is an ingenious symbiotic system to cope with risks such as nutritional deficiency, oxidation stress, and invasion of other bacteria and so on. In this review, we outline properties of symbiotic system of these fermentation microbes from our recent studies and discuss about aspects on evolution of these fermentation microbes.
