Ammonia pretreatment greatly improves enzymatic hydrolysis of grass biomass, but is reported to be ineffective for hardwood biomass. Here, we examined the effectiveness of ammonia pretreatment of biomass from six hardwood species with different contents of xylan and lignin. Ammonia pretreatment greatly improved enzymatic hydrolysis of polysaccharides in birch and willow, but was less effective for acacia, eucalyptus, and poplar. The effectiveness of ammonia pretreatment increased with xylan content but decreased with lignin content of the hardwood species. By adding a recombinant xylanase to the commercial enzyme digestion cocktail, the yield of enzymatic hydrolysis of ammonia-pretreated birch biomass was improved to a similar level to that obtained with grass biomass. Our results indicate that enzymatic hydrolysis of biomass from hardwood species having a relatively high xylan/lignin ratio can be achieved with a xylanase-enriched enzyme cocktail after ammonia pretreatment.

氨预处理可大大改善草木生物量的酶促水解，但据报道对硬木生物量无效。在这里，我们检查了来自不同木聚糖和木质素含量的6种硬木树种生物量氨气预处理的有效性。氨预处理大大改善了桦树和柳树中多糖的酶促水解作用，但对阿拉伯树胶，桉树和杨树的效果较差。氨预处理的有效性随木聚糖含量的增加而增加，但随硬木树种的木质素含量的下降而降低。通过向商业酶消化混合物中添加重组木聚糖酶，氨预处理的桦木生物质的酶水解产率提高到了与草类生物质相似的水平。