CRISPR-Cas-mediated adaptation of Thermus thermophilus HB8 to environmental stress conditions

Abstract

Bacteria experience a continual array of environmental stresses, necessitating adaptive mechanisms crucial for their survival. Thermophilic bacteria, such as Thermus thermophilus, face constant environmental challenges, particularly high temperatures, which requires robust adaptive mechanisms for survival. Studying these extremophiles provides valuable insights into the intricate molecular and physiological processes used by extremophiles to adapt and survive in harsh environments. Through meta-analysis of microarray data, we revealed the key genes in T. thermophilus HB8 that respond to various environmental stresses. The analysis revealed 20 differentially expressed genes (DEGs), including 13 upregulated and seven downregulated genes, with a threshold of|log fold change| > 1 and an adjusted p-value < 0.05. Several genes identified as up-regulated in our analysis belonged to the CRISPR-associated protein (Cas) family. To validate these findings, we further evaluated the relative expression levels of TTHB188 (cas1/casA), TTHB189 (cas2/casB), TTHB190 (cas7/casC), TTHB191 (cas5/casD), TTHB192 (cas6/casE), and TTHB193 (cas1e) using RT-qPCR under H₂O₂ and salt stress conditions. The RT-qPCR analysis revealed significant up-regulation of transcripts, casA, casB, casC, casD, casE, and cas1e under salt stress. However, under H₂O₂ stress, only, casA, casB, and casC exhibited substantial increases in expression. Our findings may indicate that the CRISPR-associated proteins significantly impact the adaptive response of T. thermophilus HB8 to various environmental stresses, particularly salt stress, highlighting its significance in extremophile survival and adaptation. This research offers an important understanding of the complex strategies used by extremophiles to survive in challenging conditions.

Keywords: Thermus thermophilus HB8; CRISPR-Associated proteins; Environmental stress; Gene expression; Meta-analysis; RT-qPCR.