“…Rational design requires adding exogenous DNA with a known function, such as the tardigrade Dsup DNA repair gene which enhances survival by 2 orders of magnitude when transferred to E. coli grown in harsh conditions ( Puig et al, 2021 ). Knowledge of specific extremophilic genes like tardigrade Dsup , as well as genome-scale models such as flux balance analysis ( Noirungsee et al, 2024 ; Saldivar et al, 2024 ), can both be invaluable for engineering ( Swayambhu et al, 2020 ). If there are no known genes with the needed function, metagenomic libraries sourced from extreme environments can search for genes that confer protection without foreknowledge of the sequence-function relationships ( Biver et al, 2014 ; Culligan et al, 2014 ; Forsberg et al, 2016 ; Ausec et al, 2017 ).…”