摘要：AbstractThis study deals with the biogeography of Antarctic microflora (Antarctica acts as best model to study microbial biogeography) such as cyanobacteria and selected halophiles with special emphasis onHalomonas variabilisandBacillus licheniformis. Halophiles are known to be resistant not only to salt stress, but also to extreme temperature, pressure, and aridity and they are capable of surviving in harsh environments such as polar regions, deep-sea habitats, and deserts. Many microbes are known to be resistant to hostile environmental conditions, and are capable of surviving in harsh environments. Our group has isolated 444 strains belonging to 28 genera of halophiles from various environments around the world. The 16S rRNA gene sequences revealed that many of the isolated strains from geographically distant habitats having different environmental conditions, were closely related to each other, with some strains possessing 100% identical sequences. Organisms possessing survival mechanism such as spore formation are usually ubiquitous. The genusHalomonasis represented by potentially endemic strains and the ubiquitousH. variabilis, while spore-formingB. licheniformisshowed cosmopolitan distribution. One potentially endemic (moderate endemicity that is regional and/or continental distribution) strain was reported from Syowa station, East Antarctica, and Mario Zucchelli station, West Antarctica, which are geographically separated by 3000 km. Moreover, 15 strains having 100% similarity withB. licheniformiswere considered cosmopolitans. The results of this work provide support for the middle-ground model that some microbes have moderate endemicity and others have cosmopolitan distribution. These results will contribute to a greater understanding of microbial biogeography with special emphasis on Antarctica.Graphical abstractDisplay OmittedHighlights► This study enlisted both cosmopolitan and geographically restricted microbes in Antarctica. ► The genusHalomonasis characterized by both endemic and cosmopolitan species. ►Bacillus licheniformiswas found cosmopolitan due to its ability to survive under extreme conditions.
