Cellular damage and response mechanisms of Candida tropicalis SHC-03 induced by toxic byproducts in corn stover hydrolysate

Abstract

This study advances the understanding of cellular damage and response mechanisms in Candida tropicalis (SHC-03) when exposed to toxic byproducts in corn stover hydrolysate, which is used for optimizing the industrial production of bioethanol and bio-based products. We found that the hydrolysate's toxic byproducts led to 84.61% accumulation of reactive oxygen species and considerable mitochondrial damage, thus inhibiting SHC-03 cell growth by 40%. The yeast combated these effects by enhancing the glutathione and thioredoxin systems, and increased their activity by 60% and 70%, respectively, to maintain intracellular redox balance. The ubiquitin–proteasome pathway was involved and endoplasmic reticulum stress was alleviated, which increased membrane thickness through ergosterol biosynthesis and improved inhibitor tolerance via upregulated expression of transporters and aldehyde reductases. These adaptations, along with the overexpression of genes related to the biosynthesis of impaired proteins and fatty acid degradation, promote SHC-03's resilience to hydrolysate toxic byproducts. Our findings could be useful for genetic modifications to increase the tolerance of fermentation strains, which could accelerate the industrial production of bioethanol and bio-based products.