Ultrastructure of Pili and Annular Structures on the Cell Wall Surface of Neisseria meningitidis

Abstract

In a survey of negatively stained preparations of' the prototype strains of' Neisseria meningitidis, pili were detected on three strains. However, these pili were detected on fewer than 5%(of' cells in populations of' these three strains. Those individual cells with pili were seldom observed to contain more than two or three pili per cell. In contrast, nearly all cells of' the nonprototype group B strain ATCC 13090 had numerous pili on their surfaces. When viewed in frozen-etched replicas, a f'ew pili were observed lying on the cell surface of' this latter strain. An annular structure was also found in frozen-etched replicas. This structure usually consisted of a series of concentric rings that were always found on the flat side of these bean-shaped cells. It is concluded that such structures represent a differentiated portion of the cell wall, which is involved in cross-wall formation during synthesis of the cell septum in dividing cells.

Relationship between colonial variation and pili morphology in a strain of Neisseria meningitidis

“…Evidence for pill on meningococci was first presented by DeVoe and Gilchfist [7] on the same strain used in the present study. We now know that the pill then shown were the large-diameter type we have described in greater detail here.…”

“…There are two major conclusions that can be drawn from the work presented here and previous work from this laboratory [7,8]. The first is that the piliation of meningococci may correl~lte well with colony type in some strains, but the t,resence of pill alone does not determine colonial morphology.…”

“…2). Small colonies were found to consist of cells elaborating pill w:[th a smaller diameter (2.5 -+ 0.26 nm) than we had previously [7] observed (Fig. 3).…”

“…Routine examinations for strain purity ~e~¢ carried out in accordance with the procedure, outlined in Neisseria Repository Bulletin, NAMRU, School of Public Health, University of California, Berkeley. Cells were grown on either M-H agar plates or M-H broth by p.'~cedures described previously [7]. Colony morphology was determined at 24 h.…”

“…[6] first mentioned ~at fibrils similar to those on gonococci had been see in cultures of meningococci. DeVo¢ and Gilch~st [7] presented evidence that strain M2092 ofN. meningitidis possessed pili under a variety of laboratory conditions both in broth and on solid media, but that pill were found only on 1-5~ of other strains of meningococci, designated prototype strains by the Neisseria repository, at University of California.…”