Abstract
Krum.hol.zi.bac.te.ri.o'ta. N.L. neut. n.
Krumholzibacterium
, type genus of the type class of the phylum; L. neut. pl. n. suff.
‐ota
, ending to denote a phylum; N.L. neut. pl. n.
Krumholzibacteriota
, the phylum of the class Krumholzibacteria.
The phylum
Candidatus
Krumholzibacteriota was proposed to accommodate genomic assemblies of yet‐uncultured microorganisms. The type species, of the genus,
Candidatus
Krumholzibacterium zodletonense Zgenome0171
T
was recovered from an anaerobic, sulfide‐ and sulfur‐rich spring in Southwestern Oklahoma, USA. The phylum comprises one described class, order, family, genus, and species. However, currently available genomes (
n
= 90) in GTDB (release 08‐RS214) are accommodated in 1 class, 6 orders, 8 families, 30 genera, and 58 species. Phylogenetically, the phylum is closely related to
Gemmatimonadota
and multiple phyla with no cultured representatives (
Ca
. Edwardsbacteria,
Ca
. Eisenbacteria,
Ca
. Latescibacterota,
Ca
. Zixibacteria, 4572‐55, ARS69, GCA‐2686955, JAAXHH01, JABDJQ01, JAGLTZ01, JAGLYR01, TA06, TA06_A, and VGIX01); all of which are part of the FCB (
Fibrobacteres
,
Chlorobia
,
Bacteroidetes
) superphylum in the Gracilicutes clade.
Candidatus
Krumholzibacteriota genomes have mainly been recovered from marine, freshwater, engineered, and host‐associated ecosystems. The prevailing
in‐situ
conditions in sampled habitats, gene content analysis, and the use of predictive machine learning‐based approaches suggest a phylum‐wide preference for anaerobic conditions, mesophilic temperatures, circumneutral pH, and low salinities. Metabolically, the type species of the type genus of the phylum is predicted to be a fermentative anaerobe with preference for amino acids over sugars as substrates. Later studies indicate that some members of the phylum harbor respiratory capacities (dissimilatory sulfate reduction, dissimilatory sulfite reduction, iron‐reduction, and high‐affinity oxygen respiration with a few members possessing the potential for low‐affinity oxygen respiration), while others possess the machinery for anaerobic degradation of aromatic hydrocarbons. Finally, although all members of
Candidatus
Krumholzibacteriota remain uncultured, a representative of the phylum was enriched in a methane‐ and iron‐fed bioreactor inoculated with Bothnian Sea sediments.
Type genus
:
Candidatus
Krumholzibacterium
Youssef et al. 2019, CL2.