Biochemical characterization and cloning of an endo-1,4-β-mannanase from Bacillus subtilis YH12 with unusually broad substrate profile

Abstract

β-Mannanases can efficiently hydrolyze both the polysaccharide mannan and manno-oligosaccharides. In order to characterize a novel mannanase for potential industrial application, an endo-1,4-β-mannanase from Bacillus subtilis YH12 was purified to homogeneity and its biochemical characterization was performed. The optimal conditions for the purified enzyme were pH 6.5 and 55°C, and it remained stable at temperature up to 60°C and pH of 4.5–7.5. The enzyme had specific activity on complex structure polysaccharide. And it showed high activity on locust bean gum, konjac powder, guar and fenugreek gums. Furthermore, it efficiently hydrolyzed xanthan, and carrageenan gums, and it exhibited no activity on starch, and xylan. The mannanase exhibited higher activity on galactomannan branched with (1→6)-linked α-d-galactose than glucomannan. The predominant products resulting from mannanase hydrolysis were 1–7 units of manno-oligosaccharides from locust bean gum, 2–7 units of manno-oligosaccharides from konjac powder, and 1–2 units of manno-oligosaccharides from xanthan gum. The B. subtilis YH12 mannanase encoding gene was successfully cloned. This study provided a novel mannanase that demonstrates potential application in food and animal feeds technology.