Understanding the Nonproductive Enzyme Adsorption and Physicochemical Properties of Residual Lignins in Moso Bamboo Pretreated with Sulfuric Acid and Kraft Pulping
Understanding the Nonproductive Enzyme Adsorption and Physicochemical Properties of Residual Lignins in Moso Bamboo Pretreated with Sulfuric Acid and Kraft Pulping
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DOI：
10.1007/s12010-016-2183-8
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发表时间：
2016-12-01
影响因子：
3
通讯作者：
Yong, Qiang
中科院分区：
文献类型：
--
作者：
Huang, Caoxing;He, Juan;Yong, Qiang
为了阐明酸预处理竹材的酶消化率明显低于碱预处理竹材的原因，本文对酸预处理竹材和硫酸盐法制浆竹材中的残余木质素进行了分离和吸附等温线分析，以评价其非生产性酶吸附程度。同时，对分离得到的木质素进行了理化性质分析，并与非生产性吸附建立了关系。结果表明，纤维素酶对酸处理竹木质素（MWLa）的吸附亲和力和结合强度显著高于对竹浆残余木质素（MWLp）的吸附亲和力和结合强度。MWLp对纤维素酶的最大吸附量为129.49 mg/g木质素，低于MWLa的160.25 mg/g木质素。当将分离的木质素添加到Avicel水解液中时，发现MWLa对酶解效率的抑制作用显著强于MWLp。纤维素酶在分离木质素上的吸附与疏水性、酚羟基和缩合度呈正相关，而与表面电荷和脂肪羟基呈负相关。这些结果表明，较高的非生产性纤维素酶的吸附和残余木质素的物理化学性质的酸预处理竹可能是负责其令人惊讶的低酶消化率。
In this work, to elucidate why the acid-pretreated bamboo shows disappointingly low enzymatic digestibility comparing to the alkali-pretreated bamboo, residual lignins in acid-pretreated and kraft pulped bamboo were isolated and analyzed by adsorption isotherm to evaluate their extents of nonproductive enzyme adsorption. Meanwhile, physicochemical properties of the isolated lignins were analyzed and a relationship was established with non-productive adsorption. Results showed that the adsorption affinity and binding strength of cellulase on acid-pretreated bamboo lignin (MWLa) was significantly higher than that on residual lignin in pulped bamboo (MWLp). The maximum adsorption capacity of cellulase on MWLp was 129.49 mg/g lignin, which was lower than that on MWLa (160.25 mg/g lignin). When isolated lignins were added into the Avicel hydrolysis solution, the inhibitory effect on enzymatic hydrolysis efficiency of MWLa was found to be considerably stronger than that with MWLp. The cellulase adsorption on isolated lignins was correlated positively with hydrophobicity, phenolic hydroxyl group, and degree of condensation but negatively with surface charges and aliphatic hydroxyl group. These results suggest that the higher nonproductive cellulase adsorption and physicochemical properties of residual lignin in acid-pretreated bamboo may be responsible for its disappointingly low enzymatic digestibility.