T. Yasui et K. Yoda, THE GROUP E-ANTIGEN IS MASKED BY THE PARACRYSTALLINE SURFACE-LAYER INLACTOBACILLUS-BREVIS, Journal of fermentation and bioengineering, 84(1), 1997, pp. 35-40
The Lactobacillus group E antigen is a cell wall glycerol teichoic aci
d. The cellular locations of the group E antigen were determined in a
total of 37 L. brevis strains, of which 34 strains possess S-layer pro
teins and three strains are S-layer protein-deficient. The group E ant
ibody was readily and reproducibly produced only by S-layer protein-de
ficient Lactobacillus brevis JCM 1170 (ATCC 367). All 37 strains teste
d were shown to possess the group E antigen by precipitation reactions
in which,whole cell extracts and group E antiserum were used. Althoug
h the three S-layer protein-deficient strains had an agglutination tit
er of 2048 or 4096, the 34 S-layer protein-carrying strains had low ag
glutination titers, ranging from 1 to 128, as determined in agglutinat
ion reactions in which intact cells and the group E antibody were used
. Treatment of L. brevis strains with sodium hydroxide solutions of be
tween 0.005 and 0.1 M resulted in removal of the S-layer protein. Afte
r removal of the S-layer proteins of the 34 S-layer protein-carrying s
trains by treatment of the cells with a 0.1 ha sodium hydroxide soluti
on, the S-layer protein-stripped cells showed an agglutination titer o
f 2048 or 4096. These results indicate that the group E antigen is exp
osed on the cell surface in S-layer protein-deficient strains, but tha
t it is masked by the S-layer proteins in strains which possess them.
The group E antigen of Lactobacillus buchneri strains classified as se
rological group E was also shown to be located beneath S-layer protein
s. The group E antibody showed marked cross reactivity with a group D
lactobacillus, L. plantarum, in precipitation reactions. The extent of
this cross reactivity was effectively reduced in an immunoassay with
a dilute alkali-treated cells and dilute group E antiserum.