Enzymatic conversion of guar gum to prebiotic mannooligosaccharide by efficient β-mannanase FsMan26 and unveiling its hydrolytic properties

A novel GH26 β-mannanase ( Fs Man26) from Fibrobacter succinogenes was expressed in Bacillus subtilis. • Fs Man26 specifically hydrolyzed galactomannan and glucomannan through an endo-acting mechanism, yielding a heterogeneous mixture of mannooligosaccharides (MOS) with diverse chain lengths and structures. • Fs Man26 efficiently converted high-concentration (20-30%) food-grade guar gum into MOS. • Guar gum hydrolysate (F-GGH) prepared by Fs Man26 contained 85.5% MOS (predominantly DP2-7), with a total MOS yield of 77.3%. • F-GGH exhibited dual functional properties by selectively stimulating probiotic growth and effectively adsorbing mycotoxins. Mannan-rich polysaccharides such as guar gum represent important renewable substrates to produce functional mannooligosaccharides (MOS) with prebiotic potential. In this study, an efficient β-1,4-mannanase Fs Man26, from Fibrobacter succinogenes S85 was identified and expressed in Bacillus subtilis . Fs Man26 demonstrated high specificity toward galactomannans and glucomannans and cleaved various mannans into MOS with varying degree of polymerization (DP). Under optimized conditions, Fs Man26 efficiently hydrolyzed high-concentration (20-30%) food-grade guar gum, achieving over 85% degradation within 8 h. Guar gum hydrolysate (F-GGH) prepared by Fs Man26 contained 85.5% MOS, and the proportion of DP2-7 oligosaccharides in MOS was 83.0%. In vitro evaluation revealed that F-GGH promotes the growth of probiotic strains such as Lactobacillus plantarum and Bacillus subtilis , but inhibits the growth of pathogenic bacteria. Moreover, F-GGH exhibited higher adsorption capacity for deoxynivalenol compared to commercial prebiotics. These findings highlight Fs Man26 as a promising biocatalyst for industrial-scale production of prebiotic MOS that suitable for food and feed applications.