| Staining |
Gram negative |
| Morphology |
Helical cells 0.5-3.0 um
in diameter and 30-180 um in length, generally displaying
2-10 complete helical turns. Ends of cells are blunt,
rounded or tapered; in fixed and stained preparations a
filament or spicule may emanate from one or both ends.
Stained preparations reveal a series of ovoid inclusions
of unknown composition which impart a chambered
appearance to the protoplasmic cylinder. Electron
microscopy of thin sections r eveals multiple cytoplasmic
vesicles bounded by a double membrane |
| Motility |
Motility is parallel to
the cell's long axis and individual cells move forward or
backward with no anterior-posterior polarity.
Translocation may include rotation about the cell's long
axis or may take the form of an irrotational travelling
helical wave. Flexing movements are common |
| Specialized structures |
Cell division is by
transverse fission.A bundle of 100 or more periplasmic
flagella (which also have been termed axial fibrils,
endoflagella or periplasmic fibrils) is intertwined with
the protoplasmic cylinder and may distend the outer
sheath to form a ridge or crest (the so-called
"crista") on the protoplasmic cylinder. The
crista is not always obvious on live cells but may be
conspicuous when the cells stop moving. It is frequently
seen by light microscopy of stained cells. Cristae may
become markedly distended, multiple swellings may appear
on the cell body, and cells may lyse or form spherical
bodies. When removed from its habitat,degenerative
changes readily occur and accompany the loss of motility |