Novel haloarchaeon Natrinema thermophila having the highest growth temperature among haloarchaea with a large genome size.

Environmental temperature is one of the most important factors for the growth and survival of microorganisms. Here we describe a novel extremely halophilic archaeon (haloarchaea) designated as strain CBA1119 ^T isolated from solar salt. Strain CBA1119 ^T had the highest maximum and optimal growth temperatures (66 °C and 55 °C, respectively) and one of the largest genome sizes among haloarchaea (5.1 Mb). It also had the largest number of strain-specific pan-genome orthologous groups and unique pathways among members of the genus Natrinema in the class Halobacteria. A dendrogram based on the presence/absence of genes and a phylogenetic tree constructed based on OrthoANI values highlighted the particularities of strain CBA1119 ^T as compared to other Natrinema species and other haloarchaea members. The large genome of strain CBA1119 ^T may provide information on genes that confer tolerance to extreme environmental conditions, which may lead to the discovery of other thermophilic strains with potential applications in industrial biotechnology.