Green and chemical-free process of enzymatic xylooligosaccharide production from corncob: Enhancement of the yields using a strategy of lignocellulosic destructuration by ultra-high pressure pretreatment

In this study, the pressures at 50-500MPa were evaluated at different time to pretreat and further enzyme hydrolysis. The ultra-high pressure (UHP) pretreatment at 100MPa for 10min led to improved accessibility of enzyme for conversion of xylan to xylooligosaccharide (XOS). The maximum XOS yield of 35.6mg/g substrate was achieved and firstly reported at 10% (w/v) of substrate, 100U of endo-xylanase/g corncobs and incubation time of 18h. The enzymatic hydrolysis efficiency was increased by 180.3% and released a high amount of xylobiose. The UHP pretreatment relatively did not affect to the composition of corncob, but decreased 34.3% of lignin. Interestingly, antioxidant activities of XOS using UHP pretreatment were higher than untreated corncob. The UHP pretreatment improved lignocellulosic destructuration and XOS yields in a shorter time without the need of chemicals, implying that UHP could be an effective pretreatment of biomass with a chemical-free process.

The effects of dietary xylooligosaccharide on mucosal parameters, intestinal microbiota and morphology and growth performance of Caspian white fish (Rutilus frisii kutum) fry

The present study investigates the effects of different levels of dietary xylooligosaccharide (XOS) on skin mucus bactericidal activity and protein content, intestinal microbiota and morphology as well as growth performance of Caspian white fish (Rutilus frisii kutum) fry. The specimens (1.54 ± 0.03 g) were fed experimental diets supplemented with different levels of XOS [0% (control), 1%, 2% and 3%] for 8 weeks. The results revealed that feeding on XOS significantly increased skin mucus antibacterial activity and protein levels (P < 0.05) and the highest levels were observed in 3% XOS treatment. The total autochthonous intestinal heterotrophic bacteria significantly increased following XOS administration in diet (P < 0.05). Administration of 2 or 3% XOS in fry diet significantly elevated the autochthonous lactic acid bacteria (P < 0.05). However, dietary XOS had no significant effect on intestinal morphology, growth performance and diet utilisation of Caspian white fish fry (P > 0.05). These results demonstrate beneficial effects of dietary XOS on different parameters of mucosal immunity (both skin mucus and intestinal microbiota) and encourage further studies regards various aspect of XOS administration in early life stages of fish.