DNA methylation confers epigenetic changes in cold-adapted microorganisms in response to cold stress.

DNA methylation modification regulates gene expression during temperature stress. The adaptation mechanisms of cold-adapted microorganisms to low temperatures have been explained at the gene and metabolic levels. However, considering the important epigenetic modification in cells, the role of genomic modification in cold-adapted microorganisms remains underexplored. This study aims to discuss the regulatory role of DNA methylation in the cold response of psychrotroph Exiguobacterium undae TRM 85608. Methylome analysis shows that the methylation level of most genes in the bacterium decreases under cold stress. Combined with transcriptome results, the expression of important cold-response genes such as ABC transporter permease and ATP-binding proteins increases, but their methylation levels decrease, which is associated with a reduction of DNA adenine methyltransferase. We believe that the reduction in genomic methylation modification caused by low temperature is a major factor in stabilizing the normal growth of the cell. The bacterium counteracts cold stress by reducing the expression of methylation modification enzymes and weakening the inhibition of cold-response gene modification. These findings provide new insights into how psychrophilic organisms adapt to low temperatures.