Transcriptional analysis of Amorphotheca resinae ZN1 on biological degradation of furfural and 5-hydroxymethylfurfural derived from lignocellulose pretreatment.
Transcriptional analysis of Amorphotheca resinae ZN1 on biological degradation of furfural and 5-hydroxymethylfurfural derived from lignocellulose pretreatment.
复制标题
木薯 ZN1 对木质纤维素预处理所得糠醛和 5-羟甲基糠醛生物降解的转录分析
DOI：
10.1186/s13068-015-0323-y
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发表时间：
2015
影响因子：
6.3
通讯作者：
Bao J
中科院分区：
文献类型：
--
作者：
Wang X;Gao Q;Bao J
背景：糠醛和5-羟甲基糠醛（HMF）是木质纤维素预处理产生的两种主要抑制剂化合物，尤其适用于稀酸、蒸汽爆炸、中性热水预处理等方法。这两种抑制剂在随后的生物转化步骤中严重抑制发酵菌的细胞生长和代谢。生物解毒菌株Amorphotheca resinae ZN1显示出其快速和完全降解糠醛和HMF为相应的醇和酸形式的非凡能力。在分子水平上阐明A. resinae ZN1的降解代谢，将有利于预处理木质纤维素生物质的解毒，为开发更强大的解毒菌株提供代谢途径信息。结果：Amorphotheca resinae ZN1能够以糠醛或HMF作为细胞生长的唯一碳源。在解毒过程中，A. resinae ZN1先将糠醛或HMF还原为糠醇或HMF醇，再以低浓度呋喃醛为中间体氧化为呋喃酸或HMF酸。细胞质量测定结果表明，糠醛对A. resinae ZN1的毒性大于HMF。为了确定A. resinae ZN1的降解机制，采用实时荧光定量PCR （qRT-PCR）方法，研究了A. resinae ZN1在糠醛和HMF胁迫下及其次生代谢产物糠醇和HMF醇胁迫下137个可能参与糠醛和HMF降解的基因的转录水平。发现2个zn依赖性醇脱氢酶基因和5个AKR/ARI基因负责糠醛和HMF转化为相应的醇。对于两种呋喃醇转化为相应的酸，在好氧条件下鉴定了3个偏好丙醇的醇脱氢酶基因、1个依赖NAD(P)（+）的醛脱氢酶基因或2个以游离氧为底物的氧化酶基因。结论：通过对A. resinae ZN1中糠醛和HMF降解为相应醇类和酸类的基因组注释、基因转录数据和抑制剂转化结果的分析，确定了与糠醛和HMF降解相关的基因。这些遗传资源为了解糠醛和羟甲基糠醛的降解机制以及用于生物炼制的高耐受性菌株的修饰提供了重要信息。
Background:Furfural and 5-hydroxymethylfurfural (HMF) are the two major inhibitor compounds generated from lignocellulose pretreatment, especially for dilute acid, steam explosion, neutral hot water pretreatment methods. The two inhibitors severely inhibit the cell growth and metabolism of fermenting strains in the consequent bioconversion step. The biodetoxification strain Amorphotheca resinae ZN1 has demonstrated its extraordinary capacity of fast and complete degradation of furfural and HMF into corresponding alcohol and acid forms. The elucidation of degradation metabolism of A. resinae ZN1 at molecular level will facilitate the detoxification of the pretreated lignocellulose biomass and provide the metabolic pathway information for more powerful biodetoxification strain development.Results:Amorphotheca resinae ZN1 was able to use furfural or HMF as the sole carbon source for cell growth. During the detoxification process, A. resinae ZN1 firstly reduced furfural or HMF into furfuryl alcohol or HMF alcohol, and then oxidized into furoic acid or HMF acid through furan aldehyde as the intermediate at low concentration level. The cell mass measurement suggested that furfural was more toxic to A. resinae ZN1 than HMF. In order to identify the degradation mechanism of A. resinae ZN1, transcription levels of 137 putative genes involved in the degradation of furfural and HMF in A. resinae ZN1 were investigated using the real-time quantitative PCR (qRT-PCR) method under the stress of furfural and HMF, as well as the stress of their secondary metabolites, furfuryl alcohol and HMF alcohol. Two Zn-dependent alcohol dehydrogenase genes and five AKR/ARI genes were found to be responsible for the furfural and HMF conversion to their corresponding alcohols. For the conversion of the two furan alcohols to the corresponding acids, three propanol-preferring alcohol dehydrogenase genes, one NAD(P)(+)-depending aldehyde dehydrogenase gene, or two oxidase genes with free oxygen as the substrate were identified under aerobic condition.Conclusions:The genes responsible for the furfural and HMF degradation to the corresponding alcohols and acids in A. resinae ZN1 were identified based on the analysis of the genome annotation, the gene transcription data and the inhibitor conversion results. These genetic resources provided the important information for understanding the mechanism of furfural and HMF degradation and modification of high tolerant strains used for biorefinery processing.