L. Margulis et al., THE ARTHROMITUS STAGE OF BACILLUS-CEREUS - INTESTINAL SYMBIONTS OF ANIMALS, Proceedings of the National Academy of Sciences of the United Statesof America, 95(3), 1998, pp. 1236-1241
In the guts of more than 25 species of arthropods we observed filament
s containing refractile inclusions previously discovered and named ''A
rthromitus'' in 1849 by Joseph Leidy [Leidy, J, (1849) Proc, Acad, Nar
, Sci. Philadelphia 4, 225-233]. We cultivated these microbes from boi
led intestines of 10 different species of surface-cleaned soil insects
and isopod crustaceans, Literature review and these observations lead
us to conclude that Arthromitus are spore-forming, variably motile, c
ultivable bacilli, As long rod-shaped bacteria, they lose their flagel
la, attach by fibers or fuzz to the intestinal epithelium, grow filame
ntously, and sporulate from their distal ends, When these organisms ar
e incubated in culture, their life history stages are accelerated by l
ight and inhibited by anoxia, Characterization of new Arthromitus isol
ates from digestive tracts of common sow bugs (Porcellio scaber), roac
hes (Gromphodorhina portentosa, Blaberus giganteus) and termites (Cryp
totermes brevis, Kalotermes flavicollis) identifies these flagellated,
spore-forming symbionts as a Bacillus sp, Complete sequencing of the
16S rRNA gene from four isolates (two sow bug, one hissing roach, one
death's head roach) confirms these as the low-G+C Gram-positive eubact
erium Bacillus cereus, We suggest that B. cereus and its close relativ
es, easily isolated from soil and grown on nutrient agar, enjoy filame
ntous growth in moist nutrient-rich intestines of healthy arthropods a
nd similar habitats.