Mining novel gene targets for improving tolerance to furfural and acetic acid in Yarrowia lipolytica using whole-genome clustered regularly interspaced short palindromic repeats interference library [RNA-seq]
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ABSTRACT: Lignocellulosic biomass is an abundant renewable resource with tremendous potential to alleviate climate crisis. Yarrowia lipolytica is an attractive biochemical production host, while the presence of inhibitors furfural and acetic acid in lignocellulosic hydrolysate restricts the efficient utilization of this resource. Given a deficient understanding of the inherent interactions between these inhibitors and cellular metabolism, sufficiently mining relevant genes is necessary. Herein, 14 novel gene targets were discovered using CRISPR interference library in Y. lipolytica, achieving tolerance to 0.35% (v/v) acetic acid (the highest concentration reported in Y. lipolytica), 4.8 mM furfural, or a combination of 2.4 mM furfural and 0.15% (v/v) acetic acid. The tolerance mechanism might involve improvements of signal transduction, PP pathway, and TCA cycle. Transcriptional repression of effective gene targets still enabled tolerance when xylose was a carbon source. This work forms a robust foundation for significantly improving microbial tolerance to inhibitors in lignocellulosic hydrolysate and profoundly revealing underlying mechanism.
Project description:Lignocellulosic biomass is an abundant renewable resource with tremendous potential to alleviate climate crisis. Yarrowia lipolytica is an attractive biochemical production host, while the presence of inhibitors furfural and acetic acid in lignocellulosic hydrolysate restricts the efficient utilization of this resource. Given a deficient understanding of the inherent interactions between these inhibitors and cellular metabolism, sufficiently mining relevant genes is necessary. Herein, 14 novel gene targets were discovered using CRISPR interference library in Y. lipolytica, achieving tolerance to 0.35% (v/v) acetic acid (the highest concentration reported in Y. lipolytica), 4.8 mM furfural, or a combination of 2.4 mM furfural and 0.15% (v/v) acetic acid. The tolerance mechanism might involve improvements of signal transduction, PP pathway, and TCA cycle. Transcriptional repression of effective gene targets still enabled tolerance when xylose was a carbon source. This work forms a robust foundation for significantly improving microbial tolerance to inhibitors in lignocellulosic hydrolysate and profoundly revealing underlying mechanism.
Project description:Genomic mutations allow bacteria to adapt rapidly to adverse stress environments. The three-dimensional conformation of the genome also may plays an important role in transcriptional regulation and environmental adaptation. Here, using chromosome conformation capture, we investigate the high-order architecture of the Zymomonas mobilis chromosome in response to genomic mutant and ambient stimuli (acetic acid and furfural, derived from lignocellulosic hydrolysate). We find that genomic mutation only influences the local chromosome contacts, whereas stress of acetic acid and furfural restrict the long-range contacts and change the chromosome organization at domain scales significantly. Further deciphering the domain feature unveils the important transcription factors, Ferric uptake regulation (Fur) proteins, which act as nucleoid-associated proteins to promote long-range (> 200 kb) chromosomal communications and regulate the expression of genes involved in stress response. Our work suggests that ubiquitous transcription factors in prokaryotes mediate chromosome organization and regulate stress-resistance genes in bacterial adaptation. RNA-seq analysis to reveal the regulation process of Fur proteins.
Project description:Genomic mutations allow bacteria to adapt rapidly to adverse stress environments. The three-dimensional conformation of the genome also may plays an important role in transcriptional regulation and environmental adaptation. Here, using chromosome conformation capture, we investigate the high-order architecture of the Zymomonas mobilis chromosome in response to genomic mutant and ambient stimuli (acetic acid and furfural, derived from lignocellulosic hydrolysate). We find that genomic mutation only influences the local chromosome contacts, whereas stress of acetic acid and furfural restrict the long-range contacts and change the chromosome organization at domain scales significantly. Further deciphering the domain feature unveils the important transcription factors, Ferric uptake regulation (Fur) proteins, which act as nucleoid-associated proteins to promote long-range (> 200 kb) chromosomal communications and regulate the expression of genes involved in stress response. Our work suggests that ubiquitous transcription factors in prokaryotes mediate chromosome organization and regulate stress-resistance genes in bacterial adaptation. Hi-C analysis revealed the three-dimensional conformation of Zymomonas mobilis.
Project description:Genomic mutations allow bacteria to adapt rapidly to adverse stress environments. The three-dimensional conformation of the genome also may play an important role in transcriptional regulation and environmental adaptation. Here, using chromosome conformation capture, we investigate the high-order architecture of the Zymomonas mobilis chromosome in response to genomic mutant and ambient stimuli (acetic acid and furfural, derived from lignocellulosic hydrolysate). We find that genomic mutation only influences the local chromosome contacts, whereas stress of acetic acid and furfural restrict the long-range contacts and change the chromosome organization at domain scales significantly. Further deciphering the domain feature unveils the important transcription factors, Ferric uptake regulation (Fur) proteins, which act as nucleoid-associated proteins to promote long-range (> 200 kb) chromosomal communications and regulate the expression of genes involved in stress response. Our work suggests that ubiquitous transcription factors in prokaryotes mediate chromosome organization and regulate stress-resistance genes in bacterial adaptation. ChIP-seq analysis of Fur proteins binding in the genome of ZM532.
Project description:In our previous study, we successfully constructed an engineered Zymomonas mobilis ZM532 strain tolerant these double inhibitors by genome shuffling, but the molecular mechanisms of tolerance to these inhibitors are still unknown. The goal of this study investigated the responses of ZM532 and wild-type ZM4 to acetic acid and furfural using Transcriptome
Project description:Background: Lignocellulosic biomass is a promising renewable feedstock for the microbial production of fuels. To release the major fermentable sugars such as glucose and xylose, pretreatment, hydrolysis, and subsequent conditioning of biomass feedstock are needed. During this process, many toxic compounds are produced or introduced which subsequently inhibit microbial growth and in many cases the production titer and rate. An understanding of the toxic effects of compounds found in hydrolysate on the fermentation microorganism is critical to improving biofuel yields in the process. One of the inhibitory compounds is furfural, liberated from hemicelluloses, which strongly inhibits the cell growth and ethanol production especially from xylose. Zymomonas mobilis is a capable ethanologenic bacterium with high ethanol productivity and high levels of ethanol tolerance. The development of robust biocatalyst to tolerate the lignocellulosic pretreatment inhibitors is one of the key elements for economic biofuel production. Results: In this study, the molecular responses of Z. mobilis to furfural, one major pretreatment inhibitor, were investigated using transcriptomic approaches of chip-based microarray. Furfural shock time course experiment with 3 g/L furfural supplemented when cells reach exponential phase and stress response experiment in the presence of 2 g/L furfural from the beginning of fermentation were carried out to study the short and long-term effect of furfural on 8b physiological and transcriptional profiles. The presence and supplementation of furfural negatively affect 8b growth in terms of final biomass and the fermentation time. Transcriptomic studies indicated that the response of 8b to furfural is dynamic, complex and differences exist between short-term shock response and long-term stress response. However, the gene function categories are similar with most downregulated genes related to translation and biosynthesis, while the furfural-upregulated genes were mostly related to cellular processes of general stress response and energy metabolism. Conclusions: Similar to previous report that acetate inhibited the growth of Z. mobilis 8b in RM using glucose or xylose as carbon source, the existence or supplementation of another major hydrolysate inhibitor furfural also inhibited 8b growth with slowing the substrate utilization and ethanol production. The difference between carbon sources is more dramatic than that of the major hydrolysate inhibitors of both NH4OAc (GSE57553) and furfural (this study). Several gene targets have been selected for genetic studies with promising preliminary results.
Project description:Furfural, phenol and acetic acid, generated during cellulosic material pretreatment, are the representative inhibitors to yeast used for ethanol production. The responses to these inhibitors in industrial yeast and the corresponding adapted strains were analyzed. Experiment Overall Design: We analyzed the transient response to inhibitors and the different transcriptions in industrial yeast and furfural-, phenol-, and acetic acid-adapted strains. Industrial yeast and the adapted strains were collected at 20 minutes after inhibitor addition. The reference samples for industrial yeast and adapted strains were collected at the same time without inhibitor addition. 2 replicates for each strain/treatment were analyzed.
Project description:This study investigated the responses of ZM532 and wild-type ZM4 to acetic acid and furfural using genomics, transcriptomics and label free quantitative proteome. By Sanger sequencing technology we re-verified of previously identified 19 mutations in ZM532, but we found a total of 23 single nucleotide polymorphisms (SNPs) in the coding sequence (CDS; 4) and intergenic region (19) in ZM532. Six SNPs were however novel in this study. We also identified a total of 1865 and 14 novel differentially expressed genes (DEGs) in ZM532 and wild-type ZM4. Further we identified 1,532 proteins by label free proteome. These proteins and genes are involved in amino acid biosynthesis, macromolecules repair, glycolysis, flagella assembly, ABC transporter, fermentation, and ATP synthesis pathways and stress response. The exclusively found genes and proteins in ZM532 confirmed and help to unravel the acetic acid and furfural tolerance mechanism between ZM532 and wild-type ZM4. May be these proteins and genes play key roles in ZM532 regulation with strong expressions under acids stress conditions. Furthermore, we knocked-out and overexpressed two differentially expressed genes (DEGs), ZMO_RS02740 up-regulated and ZMO_RS06525 down-regulated to investigate their roles in acetic acid and furfural tolerance. Our knockout and complementary experiments revealed that up-regulated expression gene ZMO RS02740 and the down-regulated expression gene ZMO-RS06525 play important roles in dealing with Furfural and acetic acid stress. ZM532 can be used to substitute ZM4 as a biocatalyst for bioethanol under acetic acid and furfural condition, with a shorter fermentation time and higher productivity.
Project description:In this study, a whole-genome CRISPRi library was developed in Y. lipolytica and applied for enforcing the tolerance to furfural and acetic acid. Several novel gene targets were discovered through NGS before and after screening. And to analyze the tolerance mechanism caused by transcriptional repression of the most prominent gene targets, the transcriptome and proteomics were performed.
Project description:Furfural, phenol and acetic acid, generated during cellulosic material pretreatment, are the representative inhibitors to yeast used for ethanol production. The responses to these inhibitors in industrial yeast and the corresponding adapted strains were analyzed.