Abstract: Beta-mannanase, as a kind of hemicellulose enzyme, has great economic value and social significance. With the aim of providing experimental evidence for its industrial production by fed-batch fermentation, Bacillus licheniformics HDYM-04 was cultured in a 5 L fermentor and fermentation conditions, feeding strategy and the amount of konjac powder addition were optimized. The optimal initial konjac addition, initial pH and inoculum size were determined as 60 g/L, 8.0 and 6.7%, respectively. The optimal fermentation conditions were temperature of 37 ℃, 300 r/min of agitation speed, and 3 L/min of aeration rate. Initial konjac powder addition at a level of 30 g followed by 90 g during the late logarithmic growth phase was identified as the optimal feeding strategy. As a result, the β-mannanase activity in fermentation broth was up to 3913 U/mL, which was 89% higher than before the optimizations (2070 U/mL).

Key words: Bacillus licheniformics, β-mannanase, conditions optimization, fed-batch, feeding strategy