COMPARATIVE ULTRASTRUCTURE OF BACTEROIDES-MELANINOGENICUS SUBSPECIES

A total of 10 strains of Bacteroides melaninogenicus subspecies were examined by transmission electron kicroscopy after conventional processing, and staining with uranyl acetate and lead citrate. All strains examined had a cell periphery with a basic ultrastructure typical of that reprted for other Gram‐negative bacteria. However, only s.s. asaccharolytucus strins exhibited a moderately electron‐dense covering layer, 16–19 nm thick, in contact with the outer membrane of the cell wall, and numerous intercellular membranous vesicles. S.s. melaninogenicus strains, in contrast to those of those of other subspecies, had no extramural structures, and exhibited a distinct, intercellular, fibrillar matrix. S.s. intermedius cells featured a 9–14 nm thick, electron‐dense extramural layer which was separated by an electron‐lucent layer of similar thickness from the outer membrane of the wall. these morphological differences may be useful in differentiating these subspecies from one another. phological differences may be useful in differentiating these subspecies from one another. Copyright © 1979, Wiley Blackwell. All rights reserved