L. Margulis et al., COMPOSITE, LARGE SPIROCHETES FROM MICROBIAL MATS - SPIROCHETE STRUCTURE REVIEW, Proceedings of the National Academy of Sciences of the United Statesof America, 90(15), 1993, pp. 6966-6970
Phenomena previously unknown in free-living spirochetes are reported:
large-sized cells with variable diameter (length to 100 mum, width bet
ween 0.4 and 3.0 mum), composite structure (smaller spirochetes inside
larger ones), and positive phototropic behavior. These bacteria, Spir
osymplokos, are compared with all other spirochete genera. The large s
pirochete, grown in mixed culture, was studied live and by transmissio
n EM. The protoplasmic cylinder was replete with spherical granules 20
-32 nm in diameter, and three to six periplasmic 26-nm flagella were i
nserted subterminally. Comparably granulated and flagellated small spi
rochetes were located inside the protoplasmic cylinder and in the peri
plasm of the large ones. When exposed to air, movement became erratic,
protoplasmic cylinders retracted to lie folded inside the outer membr
ane, and refractile membranous structures formed. From one to four str
uctures per still-moving spirochete were seen. Spirosymplokos was enri
ched from laboratory samples exposed to oxygen-rich and desiccating, b
ut not dry, conditions for at least 4 mo after removal of microbial ma
t from the field.