Zhao Lei, Cao Guang-Li, Wang Ai-Jie, Ren Hong-Yu, Zhang Kun, Ren Nan-Qi
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090 China.
State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090 China ; School of Life Science and Technology, Harbin Institute of Technology, Harbin, 150090 China.
Biotechnol Biofuels. 2014 Dec 24;7(1):178. doi: 10.1186/s13068-014-0178-7. eCollection 2014.
Biological hydrogen production from lignocellulosic biomass shows great potential as a promising alternative to conventional hydrogen production methods, such as electrolysis of water and coal gasification. Currently, most researches on biohydrogen production from lignocellulose concentrate on consolidated bioprocessing, which has the advantages of simpler operation and lower cost over processes featuring dedicated cellulase production. However, the recalcitrance of the lignin structure induces a low cellulase activity, making the carbohydrates in the hetero-matrix more unapproachable. Pretreatment of lignocellulosic biomass is consequently an extremely important step in the commercialization of biohydrogen, and for massive realization of lignocellulosic biomass as alternative fuel feedstock. Thus, development of a pretreatment method which is cost efficient, environmentally benign, and highly efficient for enhanced consolidated bioprocessing of lignocellulosic biomass to hydrogen is essential.
In this research, fungal pretreatment was adopted for enhanced hydrogen production by consolidated bioprocessing performance. To confirm the fungal pretreatment efficiency, two typical thermochemical pretreatments were also compared side by side. Results showed that the fungal pretreatment was superior to the other pretreatments in terms of high lignin reduction of up to 35.3% with least holocellulose loss (the value was only 9.5%). Microscopic structure observation combined with Fourier transform infrared spectroscopy (FTIR) analysis further demonstrated that the lignin and crystallinity of lignocellulose were decreased with better holocellulose reservation. Upon fungal pretreatment, the hydrogen yield and hydrogen production rate were 6.8 mmol H2 g(-1) pretreated substrate and 0.89 mmol L(-1) h(-1), respectively, which were 2.9 and 4 times higher than the values obtained for the untreated sample.
Results revealed that although all pretreatments could contribute to the enhancement of hydrogen production from cornstalk, fungal pretreatment proved to be the optimal method. It is apparent that besides high hydrogen production efficiency, fungal pretreatment also offered several advantages over other pretreatments such as being environmentally benign and energy efficient. This pretreatment method thus has great potential for application in consolidated bioprocessing performance of hydrogen production.
利用木质纤维素生物质生物制氢作为传统制氢方法（如水电解和煤气化）的一种有前景的替代方法，具有巨大潜力。目前，大多数关于木质纤维素生物制氢的研究集中在联合生物加工上，与专门生产纤维素酶的工艺相比，联合生物加工具有操作更简单、成本更低的优点。然而，木质素结构的顽固性导致纤维素酶活性较低，使得杂化基质中的碳水化合物更难被利用。因此，木质纤维素生物质的预处理是生物制氢商业化以及大规模将木质纤维素生物质用作替代燃料原料的极其重要的一步。因此，开发一种成本效益高、环境友好且高效的预处理方法，以增强木质纤维素生物质联合生物加工制氢的能力至关重要。
在本研究中，采用真菌预处理来提高联合生物加工性能以实现产氢量增加。为了确认真菌预处理的效率，还同时比较了两种典型的热化学预处理方法。结果表明，真菌预处理在降低木质素方面表现优异，木质素减少量高达35.3%，而全纤维素损失最少（该值仅为9.5%）。结合傅里叶变换红外光谱（FTIR）分析的微观结构观察进一步表明，木质纤维素的木质素和结晶度降低，同时全纤维素保留得更好。经过真菌预处理后，氢气产量和产氢速率分别为6.8 mmol H2 g(-1)预处理底物和0.89 mmol L(-1) h(-1)，分别是未处理样品所得值的2.9倍和4倍。
结果表明，虽然所有预处理都有助于提高玉米秸秆的产氢量，但真菌预处理被证明是最佳方法。显然，除了产氢效率高之外，真菌预处理还比其他预处理具有一些优势，如环境友好和能源高效。因此，这种预处理方法在联合生物加工产氢性能方面具有巨大的应用潜力。
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