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 [CRISPR screen]

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. Overall design: 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.