This work aims to utilize wastes from the potato starch industry to produce single-cell protein
(SCP) with high lysine content as animal feed. In this work, S-(2-aminoethyl)-L-cysteine
hydrochloride-resistant Bacillus pumilus E1 was used to produce SCP with high lysine content,
whereas Aspergillus niger was used to degrade cellulose biomass and Candida utilis was used to
improve the smell and palatability of the feed. An orthogonal design was used to optimize the
process of fermentation for maximal lysine content. The optimum fermentation conditions
were as follows: temperature of 40°C, substrate concentration of 3%, and natural pH of about
7.0. For unsterilized potato starch wastes, the microbial communities in the fermentation
process were determined by terminal restriction fragment length polymorphism analysis of
bacterial 16S rRNA genes. Results showed that the dominant population was Bacillus sp. The
protein quality as well as the amino acid profile of the final product was found to be
significantly higher compared with the untreated waste product at day 0. Additionally, acute
toxicity test showed that the SCP product was non-toxic, indicating that it can be used for
commercial processing.

Keywords: lysine, optimization, microbial communities, single cell protein