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Transcriptional analysis of Amorphotheca resinae ZN1 on biological degradation of furfural and 5-hydroxymethylfurfural derived from lignocellulose pretreatment.

Wang X, Gao Q, Bao J - Biotechnol Biofuels (2015)

Bottom Line: 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.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.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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China.

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus

Comparison of transcription levels for selected relevant genes in A. resinae ZN1 in response to 1 g/L of furfural or HMF. Quantitative expression level for each gene is log2 transformed from raw fold changes against that at 0 h. Red indicates up-regulated expression and blue for down-regulated expression as indicated by a color bar at the figure right. The different relevant genes are listed on the figure left and the color from top to bottom indicates different categories of genes: purpleADH genes, blueAKR/ARI genes
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Fig4: Comparison of transcription levels for selected relevant genes in A. resinae ZN1 in response to 1 g/L of furfural or HMF. Quantitative expression level for each gene is log2 transformed from raw fold changes against that at 0 h. Red indicates up-regulated expression and blue for down-regulated expression as indicated by a color bar at the figure right. The different relevant genes are listed on the figure left and the color from top to bottom indicates different categories of genes: purpleADH genes, blueAKR/ARI genes

Mentions: The primary step for inhibitor detoxification in A. resinae ZN1 is the fast degradation of furfural or HMF into the corresponding furfuryl alcohol or HMF alcohol to lessen the toxicity on its growth and metabolism [25, 26]. The transcription performance of the 101 genes in A. resinae ZN1 on the reduction of furfural or HMF to furfuryl alcohol or HMF alcohol, including 80 ADH genes and 21 AKR/ARI genes, were quantified using qRT-PCR as shown in Fig. 4. Under the stress of furfural, 38 ADH genes and 12 AKR/ARI genes among the total 101 genes were up-regulated by more than twofold, and 1 ADH gene was down-regulated. Under the stress of HMF, 12 ADH genes and 10 AKR/ARI genes were up-regulated, 3 ADH genes were down-regulated. All the 22 up-regulated genes in response to HMF stress were included in the 50 up-regulated genes in response to furfural, indicating that the 22 genes with the significant enhanced transcription levels were shared for both furfural and HMF reduction (Table 2).Fig. 4


Transcriptional analysis of Amorphotheca resinae ZN1 on biological degradation of furfural and 5-hydroxymethylfurfural derived from lignocellulose pretreatment.

Wang X, Gao Q, Bao J - Biotechnol Biofuels (2015)

Comparison of transcription levels for selected relevant genes in A. resinae ZN1 in response to 1 g/L of furfural or HMF. Quantitative expression level for each gene is log2 transformed from raw fold changes against that at 0 h. Red indicates up-regulated expression and blue for down-regulated expression as indicated by a color bar at the figure right. The different relevant genes are listed on the figure left and the color from top to bottom indicates different categories of genes: purpleADH genes, blueAKR/ARI genes
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4559888&req=5

Fig4: Comparison of transcription levels for selected relevant genes in A. resinae ZN1 in response to 1 g/L of furfural or HMF. Quantitative expression level for each gene is log2 transformed from raw fold changes against that at 0 h. Red indicates up-regulated expression and blue for down-regulated expression as indicated by a color bar at the figure right. The different relevant genes are listed on the figure left and the color from top to bottom indicates different categories of genes: purpleADH genes, blueAKR/ARI genes
Mentions: The primary step for inhibitor detoxification in A. resinae ZN1 is the fast degradation of furfural or HMF into the corresponding furfuryl alcohol or HMF alcohol to lessen the toxicity on its growth and metabolism [25, 26]. The transcription performance of the 101 genes in A. resinae ZN1 on the reduction of furfural or HMF to furfuryl alcohol or HMF alcohol, including 80 ADH genes and 21 AKR/ARI genes, were quantified using qRT-PCR as shown in Fig. 4. Under the stress of furfural, 38 ADH genes and 12 AKR/ARI genes among the total 101 genes were up-regulated by more than twofold, and 1 ADH gene was down-regulated. Under the stress of HMF, 12 ADH genes and 10 AKR/ARI genes were up-regulated, 3 ADH genes were down-regulated. All the 22 up-regulated genes in response to HMF stress were included in the 50 up-regulated genes in response to furfural, indicating that the 22 genes with the significant enhanced transcription levels were shared for both furfural and HMF reduction (Table 2).Fig. 4

Bottom Line: 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.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.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.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237 China.

ABSTRACT

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.

No MeSH data available.


Related in: MedlinePlus