Zheng Wei, Zheng Qin, Xue Yiyun, Hu Jiajun, Gao Min-Tian
Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
Shanghai Key Laboratory of Bio-energy Crops, School of Life Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China; Energy Research Institute of Shandong Academy of Sciences, Jinan 250014, China.
J Biosci Bioeng. 2017 Jun;123(6):731-738. doi: 10.1016/j.jbiosc.2017.01.009. Epub 2017 Feb 12.
In this study, we found that during cellulase production by Trichoderma reesei large amounts of polyphenols were released from rice straw when the latter was used as the carbon source. We identified and quantified the phenolic compounds in rice straw and investigated the effects of the phenolic compounds on cellulase production by T. reesei. The phenolic compounds of rice straw mainly consisted of phenolic acids and tannins. Coumaric acid (CA) and ferulic acid (FA) were the predominant phenolic acids, which inhibited cellulase production by T. reesei. When the concentrations of CA and FA in the broth increased to 0.06 g/L, cellulase activity decreased by 23% compared with that in the control culture. Even though the rice straw had a lower tannin than phenolic acid content, the tannins had a greater inhibitory effect than the phenolic acids on cellulase production by T. reesei. Tannin concentrations greater than 0.3 g/L completely inhibited cellulase production. Thus, phenolic compounds, especially tannins are the major inhibitors of cellulase production by T. reesei. Therefore, we studied the effects of pretreatments on the release of phenolic compounds. Ball milling played an important role in the release of FA and CA, and hot water extraction was highly efficient in removing tannins. By combining ball milling with extraction by water, the 2-fold higher cellulase activity than in the control culture was obtained.
在本研究中，我们发现，里氏木霉在以稻草为碳源生产纤维素酶的过程中，稻草会释放出大量多酚。我们对稻草中的酚类化合物进行了鉴定和定量，并研究了这些酚类化合物对里氏木霉纤维素酶生产的影响。稻草中的酚类化合物主要由酚酸和单宁组成。香豆酸（CA）和阿魏酸（FA）是主要的酚酸，它们抑制里氏木霉纤维素酶的生产。当发酵液中CA和FA的浓度增加到0.06 g/L时，纤维素酶活性与对照培养相比降低了23%。尽管稻草中单宁的含量低于酚酸，但单宁对里氏木霉纤维素酶生产的抑制作用比酚酸更强。单宁浓度大于0.3 g/L时完全抑制纤维素酶的生产。因此，酚类化合物，尤其是单宁是里氏木霉纤维素酶生产的主要抑制剂。因此，我们研究了预处理对酚类化合物释放的影响。球磨在FA和CA的释放中起重要作用，热水提取在去除单宁方面效率很高。通过将球磨与水提取相结合，获得了比对照培养高2倍的纤维素酶活性。
