Selection of Protein-Rich Saccharomyces cerevisiae from Sugarcane Mills in Thailand for Feed and Food Applications

Alternative protein sources from yeast have already been established. Yeasts which can confer high amounts of essential amino acids, and they also provided beneficial properties as prebiotics and probiotics. This study is aimed at selecting new yeast strains which can yiled high protein contents. A total of 72 microbes were isolated from sugar factories and other sources throughout Thailand. When cultured in a YPD broth medium at 30 °C at 250 rpm, the protein content of the 20 yeast isolates was found to be 38.48–44.73% cell dry weight (DW) which was higher than commercial Saccharomyces cerevisiae Angel. Interestingly, the S. cerevisiae GKS1-1, GKS1-2, GKS3-3 and SKS3-2 strains which were isolated from filter cake in sugarcane mill showed high protein contents and were rich in the essential amino acid lysine when cultivated in a 5-L bioreactor at 30 °C at 300 rpm with 1 vvm aeration. GKS1-1, GKS1-2 and GKS3-3 were also investigated for culturing in molasses medium (~ 20 g/L total sugars) at 30 °C, 250 rpm. The protein content of GKS1-1, GKS1-2 and GKS3-3 was recorded 36.83 ± 1.50, 35.90 ± 0.29 and 36.69 ± 0.55% DW, respectively, greater than that of Angel (34.69 ± 1.31% DW). Overall, these strains might be promising candidates for the production of protein for the feed and food industry.