Abstract: This article studied on the wild yeasts which were purified from the broth and rice wine, their colony morphology and cell morphology were observed, four kinds of wild yeasts were isolated, which were named YS1#, YS2#, YS3#, and YS4#. One of the wild yeast was selected, its limit fermentation and thermal performance were tested, The results showed that the limit fermentation of the wild yeast YS1# is lower than that of IB163, and thermal performance is higher than IB163. The fermentation experiments ,which used the YS1#, YS1#+IB163 and IB163, were carried out, the physical and chemical indicators were tested at the different stages. The ethanol production rate was IB163>IB163+YS1#>YS1#, and the speed of fermentation was IB163>IB163+YS1#>YS1#. The conclusions showed that the wild yeast YS1# had a little influence in the fermentation, and at a later stage, the fermentation broth which was polluted by wild yeast will continue to ferment. From generation and reduction of the diacetyl, it also showed that IB163 was restrainted by the wild yeast
Keywords: Wild yeast; Isolation; Fermentation; physical and chemical indicators; Diacetyl
