Transcriptomic analysis of cobalt stress in the marine yeastDebaryomyces hansenii

Abstract

The yeast Debaryomyces hansenii overproduces riboflavin upon exposure to subtoxic levels of cobalt (Co(+2)). However, mechanisms for survival have yet to be studied and have been hindered by D. hansenii's high genetic heterogeneity among strains. In this study, we used transcriptomic analyses and RNA-seq in order to identify differentially expressed genes in D. hansenii in response to cobalt exposure. Highly upregulated genes under this condition were identified to primarily comprise DNA damage and repair genes, oxidative stress response genes, and genes for cell wall integrity and growth. The main response of D. hansenii to heavy metal stress is the activation of non-enzymatic oxidative stress response mechanisms and control of biological production of reactive oxygen species. Our results indicate that D. hansenii does not seem to be pre-adapted to survive high concentrations of heavy metals. These organisms appear to possess genetic survival and detoxification mechanisms that enable the cells to recover from heavy metal stress.

Draft Genome Sequence of the Heavy-Metal-Tolerant Marine Yeast Debaryomyces hansenii J6

“…Gene prediction and annotation were performed by the MAKER pipeline ( 12 ), which resulted in a total of 5,717 genes. Comparing these results to the transcriptome analysis under cobalt stress for J6 ( 13 ) demonstrated that only 998 genes were not expressed under those conditions.…”

Non-Pigmented Antarctic Yeasts and Their Resistance to Toxic Metals

“…Metals substitution was performed by cobalt and nickel capable of entering the cell via the NiCoT (nickel/cobalt transporter) system of bacteria, archaebacteria, and fungi (Rodionov et al, 2006;Degen & Eitinger, 2002). Toxic Co 2+ also inhibited the growth of D. hansenii J6 cells isolated from the Swedish estuary by 60% (Gumá-Cintrón et al, 2015). Th e indicated concentration was two times lower than the inhibitory concentration of Co 2+ for the studied yeast strain D. hansenii S12.…”

“…Th ough cobalt and nickel are essential trace elements necessary for the correct biological functioning of metabolic pathways of microorganisms, they are toxic in the excessive concentration (Gumá-Cintrón et al, 2015;Forzani et al, 2001). Metals substitution was performed by cobalt and nickel capable of entering the cell via the NiCoT (nickel/cobalt transporter) system of bacteria, archaebacteria, and fungi (Rodionov et al, 2006;Degen & Eitinger, 2002).…”