Jintana Wongwigkarn, Khanittha Saemi, Wilasinee Seeweera, Kitsana Konunta, Wachiraporn Fakthong, Kannipa Tasanapak, Siriwat Kucharoenphaibul and Boonruang Khamsri
Abstract
Homemade fermented rice rinse water is a nutrient-rich due to certain yeasts produced during the process of fermentation. Nutrient-rich liquid from yeasts such as Galactomyces, isolated from Japanese sake wine, have gained commercial interest, and the ferment filtrate of Galactomyces is already used in some commercial cosmetic products. Unlike such familiar ferment filtrates, the particular yeast species present in homemade fermented rice water (FRW) and their possible benefits are yet to be identified. As an initial step to find out potential uses of yeasts in FRW, this study uses a combination of phenotypic and molecular methods to identify the yeast species present in homemade fermented rice water. FRWs were made from twenty samples of organic rice purchased from commercial shops. 42 samples were selected out of the total unidentified yeast isolates from FRW in order to investigate their biochemical characteristics using API ID 32C. PCR was then performed to amplify both the D1/D2 domain of the large subunit rDNA gene as well as the ITS1/ ITS2 regions from the yeast genomic DNA. A total of nine yeast species belonging to seven genera were identified in the fermented rice water, including Candida intermedia, C. parapsilosis, C. metapsilosis, Trichosporonasahii, Papiliotrema aspenensis, Meyerozyma caribbica, Hyphopichia burtonii, Cystobasidium calyptogenae and Rhodotorula toruloides. This study is believed to be the first to identify the yeast species in homemade FRW. The findings expand knowledge of yeasts occurred in FRW and hold potential for developing useful applications from homemade FRW.