The Diversity of Bacteriophages in Hot Springs

Bacteriophages are ubiquitous in all environments that support microbial life. This includes hot springs, which can range in temperatures between 40 and 98 °C and pH levels between 1 and 9. Bacteriophages that survive in the higher temperatures of hot springs are known as thermophages. Thermophages have developed distinct adaptations allowing for thermostability in these extreme environments, including increased G + C DNA percentages, reliance upon the pentose phosphate metabolic pathway to avoid oxidative stress, and a codon preference for those with a GNA sequence leading to increased hydrophobic interactions and disulfide bonds. In this review, we discuss the diversity of characterized thermophages in hot spring environments that span five viral families: Myoviridae, Siphoviridae, Tectiviridae, Sphaerolipoviridae, and Inoviridae. Potential industrial and medicinal applications of thermophages will also be addressed.