High butanol/acetone ratio featured ABE production using mixture of glucose and waste Pichia pastoris medium-based butyrate fermentation supernatant

In this study, butanol (ABE) fermentations were implemented in a 7 L anaerobic fermentor, by directly using the mixture of glucose solution with the corn/waste Pichia pastoris medium-based butyrate fermentation supernatants (BFS II) as the co-substrate, followed by consecutively feeding of the BFS and concentrated glucose solution. When compared with the major index of ABE fermentation using 150 g/L corn-based medium, butanol concentration could be maintained at high level of 12.7–12.8 g/L, butanol/acetone (B/A) largely increased from ~ 2.0 to 4.4–5.0, butanol yield on total carbon sources increased from 0.32–0.34 to 0.39–0.41 (mol base) with a higher butyrate/glucose consumption ratio of 37%-53%. Efficient utilization of butyrate, SO42−, amino acids, oligosaccharides, etc. in BFS II and the intracellular NADH contributed to the ABE fermentation performance improvement. The proposed strategy could be considered as the second utilization of waste Pichia pastoris, which could save raw materials/operating costs, fully use the oligosaccharides/SO42− in BFS II to relieve the working loads in downstream waste water treatment process, and increase fermentation products diversity/flexibility to deal with the varied marketing prices and requirements.