Release of glucose repression on xylose utilization in Kluyveromyces marxianus to enhance glucose-xylose co-utilization and xylitol production from corncob hydrolysate
Release of glucose repression on xylose utilization in Kluyveromyces marxianus to enhance glucose-xylose co-utilization and xylitol production from corncob hydrolysate
复制标题
释放马克斯克鲁维酵母中木糖利用的葡萄糖抑制，以增强葡萄糖-木糖的共同利用和玉米芯水解产物中木糖醇的生产
DOI：
10.1186/s12934-019-1068-2
复制
发表时间：
2019-02-01
影响因子：
6.4
通讯作者：
Hong, Jiong
中科院分区：
文献类型：
--
作者：
Hua, Yan;Wang, Jichao;Hong, Jiong
背景：木质纤维素生物质是生物化工生产中最丰富的原料之一。然而，由于微生物中的葡萄糖抑制，来自木质纤维素生物质的葡萄糖和木糖的有效共利用是一个挑战。马克斯克鲁维酵母是一种耐热性好、木糖利用效率高的酵母菌。为实现葡萄糖和木糖的共利用，分析了葡萄糖对木糖利用的抑制作用。马克思主义是必要的。结果：通过基因敲除，证实己糖激酶1（KmHXK 1）和蔗糖非发酵1（KmSNF 1）参与了木糖利用的葡萄糖阻遏，而环腺苷酸蛋白激酶A（cAMP-PKA）信号通路下游基因或蔗糖非发酵3（SNF 3）葡萄糖敏感通路下游基因的敲除并不能缓解葡萄糖阻遏。此外，破坏GAL基因表达的多拷贝抑制剂基因（KmMIG 1）减轻了葡萄糖对一些非葡萄糖（半乳糖，蔗糖和棉子糖）的抑制，但仍然保持葡萄糖对木糖利用的抑制。对木糖利用相关基因转录的实时荧光定量PCR分析证实了上述结果，并进一步证实木糖醇脱氢酶基因（KmXYL 2）是木糖利用的关键基因，受葡萄糖阻遏作用的严格调控。与SNF 1相互作用的候选靶点的许多其他基因也通过破坏进行了评估，但没有一个被证明是葡萄糖抑制木糖利用途径中的关键调节因子。因此，可能存在葡萄糖抑制木糖消耗的其他信号传导途径。基于这些结果，耐热木糖-葡萄糖共消耗平台菌株K。马克思主义是建立起来的。然后，将外源木糖还原酶和木糖特异性转运蛋白基因在平台菌株中过表达以获得YHY 013。YHY 013菌株能有效地利用玉米芯水解液或木糖母液中的葡萄糖和木糖，在廉价的有机氮源条件下生产木糖醇（> 100 g/L）。marxianus为葡萄糖木糖共利用平台菌株的构建奠定了基础。木糖醇高产菌株的获得进一步验证了平台菌株在木质纤维素生物质开发中的潜力。
Background:Lignocellulosic biomass is one of the most abundant materials for biochemicals production. However, efficient co-utilization of glucose and xylose from the lignocellulosic biomass is a challenge due to the glucose repression in microorganisms. Kluyveromyces marxianus is a thermotolerant and efficient xylose-utilizing yeast. To realize the glucose-xylose co-utilization, analyzing the glucose repression of xylose utilization in K. marxianus is necessary. In addition, a glucose-xylose co-utilization platform strain will facilitate the construction of lignocellulosic biomass-utilizing strains.Results:Through gene disruption, hexokinase 1 (KmHXK1) and sucrose non-fermenting 1 (KmSNF1) were proved to be involved in the glucose repression of xylose utilization while disruption of the downstream genes of cyclic AMP-protein kinase A (cAMP-PKA) signaling pathway or sucrose non-fermenting 3 (SNF3) glucose-sensing pathway did not alleviate the repression. Furthermore, disruption of the gene of multicopy inhibitor of GAL gene expression (KmMIG1) alleviated the glucose repression on some nonglucose sugars (galactose, sucrose, and raffinose) but still kept glucose repression of xylose utilization. Real-time PCR analysis of the xylose utilization related genes transcription confirmed these results, and besides, revealed that xylitol dehydrogenase gene (KmXYL2) was the critical gene for xylose utilization and stringently regulated by glucose repression. Many other genes of candidate targets interacting with SNF1 were also evaluated by disruption, but none proved to be the key regulator in the pathway of the glucose repression on xylose utilization. Therefore, there may exist other signaling pathway(s) for glucose repression on xylose consumption. Based on these results, a thermotolerant xylose-glucose co-consumption platform strain of K. marxianus was constructed. Then, exogenous xylose reductase and xylose-specific transporter genes were overexpressed in the platform strain to obtain YHY013. The YHY013 could efficiently co-utilized the glucose and xylose from corncob hydrolysate or xylose mother liquor for xylitol production (> 100 g/L) even with inexpensive organic nitrogen sources.Conclusions:The analysis of the glucose repression in K. marxianus laid the foundation for construction of the glucose-xylose co-utilizing platform strain. The efficient xylitol production strain further verified the potential of the platform strain in exploitation of lignocellulosic biomass.