R. Guerrero et al., SPIROSYMPLOKOS-DELTAEIBERI NOV GEN, NOV-SP - VARIABLE-DIAMETER COMPOSITE SPIROCHETE FROM MICROBIAL MATS, Archives of microbiology, 160(6), 1993, pp. 461-470
Large (up to 100 mum long), loosely coiled, free-living spirochetes wi
th variable diameters (from 0.4 to 3 mum in the same cell) were seen a
t least 40 times between August 1990 and January 1993. These spirochet
es were observed in mud water and enrichment media from highly specifi
c habitats in intertidal evaporite flats at three disjunct localities,
one in Spain and two in Mexico. All three are sites of commercial sal
tworks. Associated with Microcoleus chthonoplastes, the large spiroche
tes from Spain display phototaxis and a composite organization. Shorte
r and smaller-diameter spirochetes are seen inside both healthy and sp
ent periplasm of larger ones. Small spirochetes attached to large ones
have been observed live. From two to twelve spirochete protoplasmic c
ylinders were seen inside a single common outer membrane. A distinctiv
e granulated cytoplasm in which the granules are of similar diameter (
20-32 nm) to that of the flagella (26 nm) was present. Granule diamete
rs were measured in thin section and in negatively-stained whole-mount
preparations. Based on their ultrastructure, large size, variable dia
meter, number of flagella (3 to 6), and phototactic behavior these uni
que spirochetes are formally named Spirosymplokos deltaeiberi. Under a
noxic (or low oxygen) conditions they formed blooms in mixed culture i
n media selective for spirochetes. Cellobiose was the major carbon sou
rce in 80% seawater, the antibiotic rifampicin was added, mat from the
original field site was present and tubes were incubated in the light
at from 18-31-degrees-C. Within 1-2 weeks populations of the large sp
irochete developed at 25-degrees-C but they could not be transferred t
o fresh medium.