Microbial Protein Enrichment and Treatment of Winery Residue from Fungi and Yeast by Syntrophic Fermentation

Abstract

Yellow wine lees and rice wastewater are seasonally discharged with high amount of organics. The potential of cultivating Candida utilis and Geotrichum candidum to produce value- added single cell protein (SCP) and simultaneously bio-transform the wastes was investigated. A series of batch experiments were conducted under sterile condition. Co-culture matrix of Candida utilis and Geotrichum candidum resulted in the highest biomass and crude protein yield of 4.2g increased biomass/initial biomass and 68.4%, respectively. Response surface analysis was applied to optimize the fermentation process. The optimal conditions for SCP production with 66.3% of crude protein content were fermentation time of 4 days, solid-to-liquid ratio of 6% (w/v), inoculation proportion of 1:1 (ratio of co-cultures (v/v)), inoculum dose of 18% (v/v), and aeration rate of 1.4 volume of air/volume of reactor per minute. The soluble chemical oxygen demand (SCOD) and the total nitrogen removal efficiency were 78% and 55% respectively. Acetic acid was the main species contributing to the residual SCOD. Furthermore, the contents of essential amino acids closely matched commercial standard for fishmeal and soybean meal, providing high possibility of animal food application.