Phycisphaerales

Phycisphaerales is an order of bacteria belonging to the phylum Gracilibacteria. This phylum, formerly known as the "candidate phylum WWE3-4," is characterized by its members' phylogenetic distinctness and their often-found association with marine environments. Phycisphaerales specifically encompasses bacteria that have been identified through metagenomic studies, meaning their presence has been inferred from genetic material found in environmental samples rather than through cultivation in a laboratory.

The phylum Gracilibacteria, and thus Phycisphaerales, is notable for its metabolic capabilities, which are still being actively investigated. Members of this order are thought to play roles in various biogeochemical cycles, although their specific functions are not yet fully elucidated. Their phylogenetic position suggests they represent an ancient lineage of bacteria. Research into Phycisphaerales and Gracilibacteria is ongoing, with new discoveries continually refining our understanding of their diversity, ecology, and evolutionary history. The order's classification is based on ribosomal RNA gene sequences and comparative genomics. Due to the challenges in culturing these organisms, much of our knowledge comes from environmental DNA sequencing.