The FCB is a proposed superphylum of bacteria named after the main member phyla Fibrobacterota, Chlorobiota, and Bacteroidota. The members are considered to form a clade due to a number of conserved signature indels.

Cavalier-Smith calls the equivalent grouping a phylum by the name of Sphingobacteria. It contains the classes Chlorobiota, Fibrobacterota, Bacteroidota, and Flavobacteria. However, this megaclassification is not followed by the larger scientific community.

FCB group16S rRNA based LTP_12_2021120 marker proteins based GTDB 10-RS226
FCB "Hydrogenedentes" "Fermentibacteria" Gemmatimonadota "Latescibacteria" Fibrobacterota "Delphibacteria" "Cloacimonetes" "Zixibacteria" Calditrichota "Marinimicrobia" Bacteroidota–Chlorobiota Ignavibacteriota "Kryptonia" "Kapabacteria" Chlorobiota Rhodothermota BacteroidotaFibrobacterota Gemmatimonadota Calditrichota Ignavibacteriota Chlorobiota Rhodothermota Balneolota Bacteroidota"Tangaroaeota" (RBG-13-66-14, Coatesbacteria) "Edwardsiibacteriota" "Latescibacterota" ["Handelsmaniibacteriota"] "Zixiibacteriota" "Fermentibacterota" ["Aegiribacteria"] "Orphanbacterota" "Arandabacterota" "Joyebacterota" ["Effluvivivacota"] "Eiseniibacteriota" "Krumholzibacteriota" ["Delphinibacteriota"] "Blakebacterota" Gemmatimonadota ["Glassiibacteriota"] "Hydrothermota" ["Caldipriscota"; "Stahliibacteriota"] (WOR-3) "Cloacimonadota" Fibrobacterota ["Raymondiibacteriota"] "Marinisomatota" Calditrichota "Zhuqueibacterota" ["Cosmopoliota"] Chlorobiota (incl. Balneolota, Ignavibacteriota. "Kapaibacteriota", "Kryptoniota", Rhodothermota) "Electryoneota" (AABM5-125-24) "Delongiibacteriota" [UBA4055] (RIF26) Bacteroidota
FCB"Hydrogenedentes" "Fermentibacteria" Gemmatimonadota "Latescibacteria" Fibrobacterota "Delphibacteria" "Cloacimonetes" "Zixibacteria" Calditrichota "Marinimicrobia" Bacteroidota–Chlorobiota Ignavibacteriota "Kryptonia" "Kapabacteria" Chlorobiota Rhodothermota Bacteroidota
"Hydrogenedentes"
"Fermentibacteria" Gemmatimonadota "Latescibacteria" Fibrobacterota "Delphibacteria" "Cloacimonetes" "Zixibacteria" Calditrichota "Marinimicrobia" Bacteroidota–Chlorobiota Ignavibacteriota "Kryptonia" "Kapabacteria" Chlorobiota Rhodothermota Bacteroidota
"Fermentibacteria" Gemmatimonadota "Latescibacteria"
"Fermentibacteria"
Gemmatimonadota "Latescibacteria"
Gemmatimonadota
"Latescibacteria"
Fibrobacterota "Delphibacteria" "Cloacimonetes" "Zixibacteria" Calditrichota "Marinimicrobia" Bacteroidota–Chlorobiota Ignavibacteriota "Kryptonia" "Kapabacteria" Chlorobiota Rhodothermota Bacteroidota
Fibrobacterota
"Delphibacteria" "Cloacimonetes" "Zixibacteria" Calditrichota "Marinimicrobia" Bacteroidota–Chlorobiota Ignavibacteriota "Kryptonia" "Kapabacteria" Chlorobiota Rhodothermota Bacteroidota
"Delphibacteria"
"Cloacimonetes" "Zixibacteria" Calditrichota "Marinimicrobia" Bacteroidota–Chlorobiota Ignavibacteriota "Kryptonia" "Kapabacteria" Chlorobiota Rhodothermota Bacteroidota
"Cloacimonetes" "Zixibacteria"
"Cloacimonetes"
"Zixibacteria"
Calditrichota "Marinimicrobia" Bacteroidota–Chlorobiota Ignavibacteriota "Kryptonia" "Kapabacteria" Chlorobiota Rhodothermota Bacteroidota
Calditrichota "Marinimicrobia"
Calditrichota
"Marinimicrobia"
Bacteroidota–ChlorobiotaIgnavibacteriota "Kryptonia" "Kapabacteria" Chlorobiota Rhodothermota Bacteroidota
Ignavibacteriota "Kryptonia"
Ignavibacteriota
"Kryptonia"
"Kapabacteria" Chlorobiota Rhodothermota Bacteroidota
"Kapabacteria"
Chlorobiota Rhodothermota Bacteroidota
Chlorobiota
Rhodothermota Bacteroidota
Rhodothermota
Bacteroidota
Fibrobacterota Gemmatimonadota Calditrichota Ignavibacteriota Chlorobiota Rhodothermota Balneolota Bacteroidota
Fibrobacterota Gemmatimonadota
Fibrobacterota
Gemmatimonadota
Calditrichota Ignavibacteriota Chlorobiota Rhodothermota Balneolota Bacteroidota
Calditrichota
Ignavibacteriota Chlorobiota Rhodothermota Balneolota Bacteroidota
Ignavibacteriota Chlorobiota
Ignavibacteriota
Chlorobiota
Rhodothermota Balneolota Bacteroidota
Rhodothermota
Balneolota Bacteroidota
Balneolota
Bacteroidota
"Tangaroaeota" (RBG-13-66-14, Coatesbacteria) "Edwardsiibacteriota" "Latescibacterota" ["Handelsmaniibacteriota"] "Zixiibacteriota" "Fermentibacterota" ["Aegiribacteria"] "Orphanbacterota" "Arandabacterota" "Joyebacterota" ["Effluvivivacota"] "Eiseniibacteriota" "Krumholzibacteriota" ["Delphinibacteriota"] "Blakebacterota" Gemmatimonadota ["Glassiibacteriota"] "Hydrothermota" ["Caldipriscota"; "Stahliibacteriota"] (WOR-3) "Cloacimonadota" Fibrobacterota ["Raymondiibacteriota"] "Marinisomatota" Calditrichota "Zhuqueibacterota" ["Cosmopoliota"] Chlorobiota (incl. Balneolota, Ignavibacteriota. "Kapaibacteriota", "Kryptoniota", Rhodothermota) "Electryoneota" (AABM5-125-24) "Delongiibacteriota" [UBA4055] (RIF26) Bacteroidota
"Tangaroaeota" (RBG-13-66-14, Coatesbacteria)
"Edwardsiibacteriota" "Latescibacterota" ["Handelsmaniibacteriota"] "Zixiibacteriota" "Fermentibacterota" ["Aegiribacteria"] "Orphanbacterota" "Arandabacterota" "Joyebacterota" ["Effluvivivacota"] "Eiseniibacteriota" "Krumholzibacteriota" ["Delphinibacteriota"] "Blakebacterota" Gemmatimonadota ["Glassiibacteriota"] "Hydrothermota" ["Caldipriscota"; "Stahliibacteriota"] (WOR-3) "Cloacimonadota" Fibrobacterota ["Raymondiibacteriota"] "Marinisomatota" Calditrichota "Zhuqueibacterota" ["Cosmopoliota"] Chlorobiota (incl. Balneolota, Ignavibacteriota. "Kapaibacteriota", "Kryptoniota", Rhodothermota) "Electryoneota" (AABM5-125-24) "Delongiibacteriota" [UBA4055] (RIF26) Bacteroidota
"Edwardsiibacteriota" "Latescibacterota" ["Handelsmaniibacteriota"] "Zixiibacteriota" "Fermentibacterota" ["Aegiribacteria"] "Orphanbacterota" "Arandabacterota" "Joyebacterota" ["Effluvivivacota"] "Eiseniibacteriota" "Krumholzibacteriota" ["Delphinibacteriota"] "Blakebacterota" Gemmatimonadota ["Glassiibacteriota"]
"Edwardsiibacteriota" "Latescibacterota" ["Handelsmaniibacteriota"] "Zixiibacteriota"
"Edwardsiibacteriota"
"Latescibacterota" ["Handelsmaniibacteriota"] "Zixiibacteriota"
"Latescibacterota" ["Handelsmaniibacteriota"]
"Zixiibacteriota"
"Fermentibacterota" ["Aegiribacteria"] "Orphanbacterota" "Arandabacterota" "Joyebacterota" ["Effluvivivacota"] "Eiseniibacteriota" "Krumholzibacteriota" ["Delphinibacteriota"] "Blakebacterota" Gemmatimonadota ["Glassiibacteriota"]
"Fermentibacterota" ["Aegiribacteria"]
"Orphanbacterota" "Arandabacterota" "Joyebacterota" ["Effluvivivacota"] "Eiseniibacteriota" "Krumholzibacteriota" ["Delphinibacteriota"] "Blakebacterota" Gemmatimonadota ["Glassiibacteriota"]
"Orphanbacterota" "Arandabacterota" "Joyebacterota" ["Effluvivivacota"] "Eiseniibacteriota" "Krumholzibacteriota" ["Delphinibacteriota"]
"Orphanbacterota" "Arandabacterota" "Joyebacterota" ["Effluvivivacota"]
"Orphanbacterota"
"Arandabacterota" "Joyebacterota" ["Effluvivivacota"]
"Arandabacterota"
"Joyebacterota" ["Effluvivivacota"]
"Eiseniibacteriota" "Krumholzibacteriota" ["Delphinibacteriota"]
"Eiseniibacteriota"
"Krumholzibacteriota" ["Delphinibacteriota"]
"Blakebacterota" Gemmatimonadota ["Glassiibacteriota"]
"Blakebacterota"
Gemmatimonadota ["Glassiibacteriota"]
"Hydrothermota" ["Caldipriscota"; "Stahliibacteriota"] (WOR-3) "Cloacimonadota" Fibrobacterota ["Raymondiibacteriota"] "Marinisomatota" Calditrichota "Zhuqueibacterota" ["Cosmopoliota"] Chlorobiota (incl. Balneolota, Ignavibacteriota. "Kapaibacteriota", "Kryptoniota", Rhodothermota) "Electryoneota" (AABM5-125-24) "Delongiibacteriota" [UBA4055] (RIF26) Bacteroidota
"Hydrothermota" ["Caldipriscota"; "Stahliibacteriota"] (WOR-3) "Cloacimonadota"
"Hydrothermota" ["Caldipriscota"; "Stahliibacteriota"] (WOR-3)
"Cloacimonadota"
Fibrobacterota ["Raymondiibacteriota"] "Marinisomatota" Calditrichota "Zhuqueibacterota" ["Cosmopoliota"] Chlorobiota (incl. Balneolota, Ignavibacteriota. "Kapaibacteriota", "Kryptoniota", Rhodothermota) "Electryoneota" (AABM5-125-24) "Delongiibacteriota" [UBA4055] (RIF26) Bacteroidota
Fibrobacterota ["Raymondiibacteriota"]
"Marinisomatota" Calditrichota "Zhuqueibacterota" ["Cosmopoliota"] Chlorobiota (incl. Balneolota, Ignavibacteriota. "Kapaibacteriota", "Kryptoniota", Rhodothermota) "Electryoneota" (AABM5-125-24) "Delongiibacteriota" [UBA4055] (RIF26) Bacteroidota
"Marinisomatota" Calditrichota "Zhuqueibacterota" ["Cosmopoliota"] Chlorobiota (incl. Balneolota, Ignavibacteriota. "Kapaibacteriota", "Kryptoniota", Rhodothermota)
"Marinisomatota"
Calditrichota "Zhuqueibacterota" ["Cosmopoliota"] Chlorobiota (incl. Balneolota, Ignavibacteriota. "Kapaibacteriota", "Kryptoniota", Rhodothermota)
Calditrichota "Zhuqueibacterota" ["Cosmopoliota"]
Calditrichota
"Zhuqueibacterota" ["Cosmopoliota"]
Chlorobiota (incl. Balneolota, Ignavibacteriota. "Kapaibacteriota", "Kryptoniota", Rhodothermota)
"Electryoneota" (AABM5-125-24) "Delongiibacteriota" [UBA4055] (RIF26) Bacteroidota
"Electryoneota" (AABM5-125-24)
"Delongiibacteriota" [UBA4055] (RIF26) Bacteroidota
"Delongiibacteriota" [UBA4055] (RIF26)
Bacteroidota

An analogous situation is seen with the PVC group/Planctobacteria.

The Bacteroidota–Chlorobiota group in brown is visible on this 2016 tree of life using ribosomal protein sequences

See also