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Appl. Environ. Microbiol., Jan 1995, 130-137, Vol 61, No. 1
JS Brooke, SF Koval and TJ Beveridge
A green Chlorobium sp. with spinae, strain JSB1, was isolated from an
enrichment culture previously obtained from Fayetteville Green Lake, N.Y.
(J. S. Brooke, J. B. Thompson, T. J. Beveridge, and S. F. Koval, Arch.
Microbiol. 157:319-322, 1992). Cells were gram-negative, nonmotile rods
which contained bacteriochlorophyll c and chlorosomes. Spinae were best
seen by transmission electron microscopy in thin sections of cells fixed in
the presence of tannic acid. High-resolution scanning electron microscopy
showed the spinae randomly distributed at the cell surface and at the
junctions between cells. Spinae were physically sheared from cells and
isolated from the culture supernatant by ultrafiltration. As observed by
electron microscopy, spinae demonstrated unusual structural stability when
exposed for 1 h at 37 deg C to chemical treatments such as hydrogen
bond-breaking agents, detergents, metal-chelating agents, proteases, and
organic solvents. They were stable for 1 h at 37 deg C over the pH range
2.3 to 9.9 and in 1 M HCl and 1 M NaOH. The structural integrity of the
spinae was also maintained when spinae were subjected to harsher treatments
of autoclaving in 2% (wt/vol) sodium dodecyl sulfate and exposure to
dithiothreitol at pH 9 for 1 h at 100 deg C. Partially dissociated spinae
were obtained after 5 h at 100 deg C in 1 M HCl and 1 M NaOH. In acid, the
tubular spinae became amorphous structures, with no helical striations
visible. In alkali, the spinae had dissociated into irregular aggregates of
disks. Since both high temperature and extremes of pH were required to
achieve partial dissociation of the spinae, the strength of the structure
presumably comes from covalent bonding.
Copyright © 1995, American Society for Microbiology
Unusually Stable Spinae from a Freshwater Chlorobium sp
Department of Microbiology and Immunology, University of Western Ontario, London, Ontario N6A 5C1, and Department of Microbiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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