Whole Genome Sequencing of Kodamaea ohmeri SSK and Its Characterization for Degradation of Inhibitors from Lignocellulosic Biomass.

Lignocellulosic biomass is widely recognized as a renewable resource for bioconversion. However, the presence of inhibitors such as furfural, 5-HMF, and acetic acid can inhibit cell growth, thereby affecting the overall efficiency of the bioconversion process. The studies on the degradation of lignocellulosic hydrolysate inhibitors by Saccharomyces cerevisiae have been limited. In this research, a yeast strain Kodamaea ohmeri can degrade inhibitors furfural, 5-HMF, and acetic acid, and the genome sequence of the strain was analyzed. Furthermore, the molecular detoxification mechanism of K. ohmeri SSK against lignocellulosic hydrolysate inhibitors was predicted using whole genome sequencing. Annotation based on the COG/KEGG databases identified 57 key detoxification genes, including the alcohol dehydrogenase (ADH) gene, aldo-keto/aldehyde reductase (AKR/ARI) gene, and aldehyde dehydrogenase (ALDH) gene. Stress tolerance experiments revealed that the maximum tolerance concentration for the strain was 5.2 g/L of furfural, 2.5 g/L of 5-HMF, and 5.9 g/L of acetic acid, respectively. A NAD(P)(+)-dependent bifunctional enzyme with possible ADH and ARI activities was found by conserved domain analysis. Phylogenetic analysis indicated that this enzyme shared 99% homology with the detoxification enzyme from S. cerevisiae S288C (GenBank: Q04894.1). This study represents the first comprehensive analysis of the inhibitor detoxification network in K. ohmeri SSK from a genome perspective, providing theoretical targets and design strategies for developing highly efficient biorefinery strains.