Extraction of water-soluble xylan from wheat bran and utilization of enzymatically produced xylooligosaccharides by Lactobacillus, Bifidobacterium and Weissella spp.

- Microwave pretreatment of wheat bran can be used to efficiently extract xylan.
- Different pretreatment conditions affect the yield and structure of extracted xylan.
- Weissella spp. and lactic acid bacteria utilised xylanase produced oligosaccharides.
- Enzymatic hydrolysed xylan enhanced bacterial production of lactic- and acetic acid.

Xylan was extracted from wheat bran after heat pretreatment in water using either an autoclave or a microwave oven. Xylooligosaccharides (XOS) were produced from the xylan using the thermostable xylanase RmXyn10A and the potential prebiotic properties of XOS were studied in vitro with different human gut bacteria: Lactobacillus brevis (DSMZ 1269), Bifidobacterium adolescentis (ATCC 15703) and two strains of recently isolated lactic acid bacteria from the species pair Weissella cibaria/confusa. The highest yield of (arabino)xylan with the heat pretreatment was obtained at 185 °C for 10 min. Higher temperature led to fewer arabinose substitutions present on the backbone which in turn resulted in a slightly more efficient enzymatic hydrolysis by RmXyn10A.Using the produced XOS hydrolysate as carbon source, xylobiose uptake was confirmed for all bacterial species studied while xylotriose uptake could be confirmed for B. adolescentis and the Weissella strains. The negative control strain Escherichia coli (BL 21) did not use XOS as a carbon source. L. brevis, B. adolescentis and the Weissella spp. all showed growth on XOS, verified by increases in cell density, lactic acid and acetic acid production after 48 h incubation. Corresponding increases were not found using the non-hydrolysed xylan as carbon source.