These are all Streptococcus species, most Leuconostoc, Weissella, and Oenococcus species, and some Lactococcus species. PsB are also found among several species of other genera (in particular, Enterococcus faecalis). All PsB have peptidoglycan (basis of their cell membrane) containing interpeptide bridges of type (L-Ala)-(L-Ala) and/or (L-Ser)-(L-Ala).
This peptidoglycan is similar to peptidoglycan of pathogenic bacterium Streptococcus pyogenes.
Within YN-model of psoriasis pathogenesis, it is assumed that antigen that causes inadequate response of skin immune system originates from fragments of interpeptide bridges of this particular peptidoglycan. And this antigen enters skin inside blood neutrophils, which, firstly, endocytose bacterial products in blood, secondly, are attracted to inflamed skin and, thirdly, can undergo NETosis (self-destruction) in inflamed skin ( Peslyak & Korotky 2020 ).
Formation of these bridges in peptidoglycan is due to presence of enzymes such as murM and murN.
The murM is enzyme that provides addition of serine/alanine (first amino acid starting from Lys) during formation of interpeptide bridge in peptidoglycan. In absence of this enzyme, there will be almost no bridges. What exactly is added (serine or alanine) depends on allele of murM gene.
The murN is enzyme that provides addition of alanine (second amino acid starting from Lys) during formation of interpeptide bridge in peptidoglycan. In absence of this enzyme, bridge will be one amino acid long.
In different bacteria, formation of interpeptide bridges is provided by different murMN genes (Peslyak & Korotky 2020).
KEGG database identifies all bacterial species (among those included in this database) that have genes that ensure secretion of both enzymes, i.e. both murM and murN types.
PsB – presumable psoriagenic bacteria are all species of Streptococcus,
as well as (in alphabetical order) other bacteria:
Arthrobacter sp.PGP41
Enterococcus faecalis,
Enterococcus silesiacus,
Eubacterium sulci,
Furfurilactobacillus rossiae L1,
Lactococcus carnosus,
Lactococcus formosensis,
Lactococcus garvieae,
Lactococcus petauri,
Lactococcus piscium,
Lactococcus raffinolactis
Leuconostoc carnosum,
Leuconostoc citreum,
Leuconostoc garlicum,
Leuconostoc gasicomitatum,
Leuconostoc gelidum,
Leuconostoc kimchii,
Leuconostoc koreense,
Leuconostoc lactis,
Leuconostoc mesenteroides,
Leuconostoc pseudomesenteroides,
Leuconostoc sp.C2
Melissococcus plutonius
Oenococcus oeni,
Oenococcus sicerae,
Oenococcus sp.UCMA16435
Pseudarthrobacter psychrotolerans,
Pseudarthrobacter sulfonivorans
Weissella ceti,
Weissella cibaria,
Weissella coleopterorum,
Weissella diestrammenae,
Weissella hellenica,
Weissella jogaejeotgali,
Weissella koreensis,
Weissella paramesenteroides,
Weissella soli,
Weissella tructae,
Weissella viridescens
This list was compiled as of April 3, 2025. It is updated as KEGG database is replenished and refined.