Prebiotics marmooligosaccharides(MOS) is an important bifidus factor which can be used as functional food or drug.The use of β-mannanase from microbe to modify the beer yeast cell wall is an important way to the preparation of MOS.By functional plates and marnanase activity,10 strains which can produce β-mannanase were isolated from the soil.These strains are Bacillus spp.