A solid state fungal fermentation-based strategy for the hydrolysis of wheat straw.
Bottom Line: The addition of yeast extract (0.5% w/v) and minerals significantly improved the cellulase production, to 24.0 ± 1.76 U/g.The hydrolysis of the fermented wheat straw using the fungal culture filtrate or commercial cellulase Ctec2 was performed, resulting in 4.34 and 3.13 g/L glucose respectively.It indicated that the fungal filtrate harvested from the fungal fermentation of wheat straw contained a more suitable enzyme mixture than the commercial cellulase.
Affiliation: School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, Leicestershire LE12 5RD, United Kingdom.Show MeSH
Mentions: As shown in Table 2, the dilute acid and acid soaking modified wheat straw resulted in high enzyme activity at day 1. This may be due to the dilute acid and acid soaking removing the hemicellulose (Ibbett et al., 2011) exposing cellulose to A. niger. The induction of cellulase by wheat straw was a fast process in liquid culture, taking around 6 h (Delmas et al., 2012). Although the fermentation condition was different to liquid culture, the induction of cellulase in solid state fermentation could be fast as well. Therefore, by the first day, A. niger excreted higher amount of cellulase than fermentations using autoclave modified wheat straw and non-treated wheat straw. However, both dilute acid and acid soaking modified wheat straw led to low cellulase at day 5. In the dilute acid experiment, the enzyme activity dropped to 4.43 U/g at day 5, which was only 43% of the peak cellulase activity at day 3. The reduction in cellulose content and nutrient supplement may be the cause of the decrease of the cellulase activity (Singh et al., 2011). Surprisingly, A. niger was able to produce a significant amount of cellulase (5.83 U/g) using crude wheat straw (Table 2). This indicated that a cost effective biorefining process could be developed based on only crude wheat straw For the dilute acid-modified wheat straw, the highest cellulase activity was 10.2 U/g at day 3 (Table 2, Fig. 4). It showed that cellulase produced from the dilute acid-modified wheat straw is significantly different from the non-treated and acid soaking-modified wheat straw. However, there was no significant difference between the dilute acid-modified wheat straw and autoclaved wheat straw. Therefore, here we used the autoclaved wheat straw as the substrate due to its relatively simple operation.
Affiliation: School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, Leicestershire LE12 5RD, United Kingdom.