Gossypol detoxification and lysine enrichment in Cottonseed cake by solid state fermentation

This study investigated the effect of mixed microbial cultures on gossypol and lysine levels in cottonseed cake (CSK) during solid state fermentation (SSF). The fermented CSK showed 71.4 % and 76.2 % free gossypol (FG) reduction and 77.0 % and 67.3 % bound gossypol (BG) reduction in Pleurotus sajor-caju + Saccharomyces cerevisiae and Candida tropicalis + S. cerevisiae treated samples respectively. The gossypol (FG and BG) reduction and lysine improvement in CSK was maximum after 36 h of incubation during SSF. The addition of crude enzyme extract containing protease activity of 500 and 400 U/g in CSK resulted in decrease of BG level. The High Performance Liquid Chromatography (HPLC) analysis of fermented CSK showed that lysine content was increased significantly from 0.92 to 1.36 in P sajor-caju + S. cerevisiae and 1.54 in C. tropicalis + S. cerevisiae. The fungal count (cfu/g) was increased to 100 fold in fermented CSK. To our knowledge, this is the first report on SSF process for BG reduction and lysine enrichment in CSK. Keywords: Bound Gossypol; Cottonseed cake; Free Gossypol; Lysine; Protease activity; Solid State Fermentation.