Genomic and metabolic network properties in thermophiles and psychrophiles compared to mesophiles.

Thermophiles and psychrophiles, adapted to extreme temperatures, thrive in hot and cold environments, respectively. Despite their importance to biotechnology and environmental research, their adaptation mechanisms remain unclear. We have performed a comparative analysis of the genomes and metabolic networks of these species. Psychrophiles were found to have larger genomes, more genes, bigger metabolic networks, fewer metabolite exchanges, and higher growth rates compared to thermophiles. These species show amino acid and codon preferences: thermophiles favor GC-rich codons, while psychrophiles prefer AT-rich ones. This aligns with their genomic G + C content, which is higher in thermophiles and linked to their growth. Compared to mesophiles, species which are living in normal conditions, extremophiles show significantly reduced metabolite exchange, with psychrophiles importing fewer nutrients and thermophiles exporting fewer metabolites. Both groups exhibit distinct active metabolic reactions enriched with unique and important processes. In summary, both thermophiles and psychrophiles exhibit unique genomic profiles and metabolic network properties that likely support their adaptation to extreme temperatures.