CRISPRi-induced transcriptional regulation of IAH1 gene and its influence on volatile compounds profile in Kluyveromyces marxianus DU3.

Mezcal is a traditional Mexican distilled beverage, known for its marked organoleptic profile, which is influenced by several factors, such as the fermentation process, where a wide variety of microorganisms are present. Kluyveromyces marxianus is one of the main yeasts isolated from mezcal fermentations and has been associated with ester synthesis, contributing to the flavors and aromas of the beverage. In this study, we employed CRISPR interference (CRISPRi) technology, using dCas9 fused to the Mxi1 repressor factor domain, to down-regulate the expression of the IAH1 gene, encoding for an isoamyl acetate-hydrolyzing esterase, in K. marxianus strain DU3. The constructed CRISPRi plasmid successfully targeted the IAH1 gene, allowing for specific gene expression modulation. Through gene expression analysis, we assessed the impact of IAH1 down-regulation on the metabolic profile of volatile compounds. We also measured the expression of other genes involved in volatile compound biosynthesis, including ATF1, EAT1, ADH1, and ZWF1 by RT-qPCR. Results demonstrated successful down-regulation of IAH1 expression in K. marxianus strain DU3 using the CRISPRi system. The modulation of IAH1 gene expression resulted in alterations in the production of volatile compounds, specifically ethyl acetate, which are important contributors to the beverage's aroma. Changes in the expression levels of other genes involved in ester biosynthesis, suggesting that the knockdown of IAH1 may generate intracellular alterations in the balance of these metabolites, triggering a regulatory response. The application of CRISPRi technology in K. marxianus opens the possibility of targeted modulation of gene expression, metabolic engineering strategies, and synthetic biology in this yeast strain.