Kiritimatiellota emend

Abstract

Abstract Ki.ri.ti.ma.ti.el.lo'ta. N.L. fem. dim. n. Kiritimatiella , type genus of the phylum; N.L. neut. pl. n. suff. ‐ ota , ending to denote a phylum; N.L. neut. pl. n. Kiritimatiellota , the Kiritimatiella phylum. Analysis of environmental 16S rRNA gene sequences suggests that members of this phylum prefer animal intestines and anoxic aquatic niches ranging in salinity from hypersaline to freshwater. These data further indicate that most members of the Kiritimatiellota are mesophilic and neutrophilic, being adapted to moderate habitats. Cells of cultivated strains divide by binary fission, do not form intracellular membranes, are spherical, nonmotile, and non‐spore‐forming. They have a cell wall of the Gram‐negative type that contains peptidoglycan and an outer membrane. Strains available in pure culture produce transparent exopolymers during growth. Based on the habitat preference, it can be concluded that most representatives are anaerobic bacteria with a fermentative and saccharolytic type of metabolism. In sequenced genomes of some representatives, extraordinarily high numbers of genes encoding putative glycoside hydrolases and sulfatases were detected, which may be necessary for the degradation of complex sulfated polysaccharides typically occurring in the animal intestine or marine environments (Spring et al., 2016; van Vliet et al., 2020). Cellular fatty acid patterns of axenic cultures were dominated by straight‐chain (C 18:0 ) and iso ‐branched fatty acids ( iso ‐C 12:0 , iso ‐C 14:0 ). The major polar lipids were identified as phosphatidylglycerol and diphosphatidylglycerol (cardiolipin). In some strains, respiratory lipoquinones (menaquinones MK‐6 – MK‐9) were detected. The genome sizes among described representatives of this phylum range from 2.9 to 8.6 Mb. DNA G + C content (mol%) : 53–63 (genome analyses). Type genus : Kiritimatiella Spring et al. 2016, VL174.