S-2-Aminoethyl-L-cysteine hydrochloride

The present study aimed at reducing the pollution of the waste generated by the potato starch industry to the environment and transform the potato pulp and wastewater into single-cell protein (SCP) to be used as animal feed. The chemical oxygen demand of the wastewater was reduced from 26,700 to 9,100 mg/L by batch fermentation with mixed cultures in an aerated 10-L fermenter. The SCP products, with a crude protein content of 46.09 % (higher than soybean meal), were found palatable and safe for mice. During the treatment process, the microbial community was analyzed using the terminal restriction fragment length polymorphism for bacterial 16S rRNA genes. The results of the analysis suggested that Curacaobacter/Pseudoalteromonas and Paenibacillus/Bacillus were the main microorganisms in treating potato starch processing wastes. The 150-m(3)-scale fermentation demonstrated a potential for treatment in industrial applications. Fermentation of potato pulp and wastewater without adding an extra nitrogen source was a novel approach in treating the potato starch processing waste.

Yellow wine lees (YWL) are the main co-products in yellow wine industry with unbalanced amino acid (AA) profiles. Solid-state fermentation was employed in this study to upgrade the YWL for ruminant animals. A 3 × 3 orthogonal design was conducted to optimize the fermentation condition for optimal crude protein (CP) yield as follows: ratio of water to total solid medium at 50 : 100 (v/w), temperature of 30°C, and ratio of Candida utilis to Bacillus subtilis at 2 : 1. The contents of CP, peptides and AA of fermented products were 14·5, 40·9 and 26·1% higher than those of the unfermented respectively. In particular, the essential AA were highly improved, especially for lysine and methionine. The fermentation increased the in vitro microbial protein synthesis with higher CP digestibility and dramatically enhanced the ability of scavenging free radicals of the YWL. It is concluded that the microbial pretreatment can greatly improve the nutritional value of YWL, making these materials more suitable as feeds for animals, including ruminants. SIGNIFICANCE AND IMPACT OF THE STUDY: Yellow wine lees (YWL) are the main co-products in yellow wine industry with unbalanced amino acid (AA) profiles and are not well utilized. A strain combination of Candida utilis and Bacillus subtilis was employed to upgrade YWL. Contents of crude protein and peptides of YWL were greatly increased by microbial fermentation. Essential AAs of YWL were highly improved after the solid-state fermentation and no negative impact was observed in in vitro digestibility. Fermented YWL may be a good feed source for ruminants.

When cultivated aerobically, Aspergillus niger hyphae produced extracellular glucoamylase, which catalyzes the saccharification of unliquified potato starch into glucose, but not when grown under anaerobic conditions. The Km and Vmax of the extracellular glucoamylase were 652.3 mg starch l-1 and 253.3 mg glucose l-1 min-1, respectively. In mixed culture of A. niger and Saccharomyces cerevisiae, oxygen had a negative influence on the alcohol fermentation of yeast, but activated fungal growth. Therefore, oxygen is a critical factor for ethanol production in the mixed culture, and its generation through electrolysis of water in an electrochemical bioreactor needs to be optimized for ethanol production from starch by coculture of fungal hyphae and yeast cells. By applying pulsed electric fields (PEF) into the electrochemical bioreactor, ethanol production from starch improved significantly: Ethanol produced from 50 g potato starch l-1 by a mixed culture of A. niger and S. cerevisiae was about 5 g l-1 in a conventional bioreactor, but was 9 g l-1 in 5 volts of PEF and about 19 g l-1 in 4 volts of PEF for 5 days.