On the fate of ingested Bacillus spores.
Spores of various Bacillus species, including B. subtilis, B. cereus and B. clausii, are used as probiotics, although they are generally absent from the normal microflora of man. We used two nonpathogenic Bacillus species, B. subtilis and B. clausii, to follow the fate of spores inoculated intragastrically in mice. We did not find detectable amounts of vegetative cells in intestinal samples, probably because of high toxicity of the conjugated bile salt taurodeoxycholic acid against Bacillus species. Both spores and cells were detected in the lymph nodes and spleen of one mouse. Our results indicate that Bacillus is present in the intestinal tract solely as spores and that nonpathogenic Bacillus spores may germinate in lymphoid organs, a finding reminiscent of B. anthracis germination in macrophages. These results indicate that any claimed probiotic effect of B. subtilis should be due to spores or, alternatively, to vegetative growth outside the intestine.
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Dipartimento di Biologia Molecolare, Università di Siena, Italy.
Braccini
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Ricca
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De Felice
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Morelli
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Pozzi
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D000284:Administration, Oral; D000818:Animals; D001407:Bacillus / Q000187:drug effects / Q000502:physiology*; D001412:Bacillus subtilis / Q000187:drug effects / Q000502:physiology; D001647:Bile Acids and Salts / Q000494:pharmacology; D003840:Deoxycholic Acid / Q000494:pharmacology; D005260:Female; D007422:Intestines / Q000382:microbiology*; D008198:Lymph Nodes / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D019936:Probiotics; D013171:Spores, Bacterial / Q000187:drug effects / Q000502:physiology*; D013657:Taurodeoxycholic Acid / Q000494:pharmacology
D001647:Bile Acids and Salts; D003840:Deoxycholic Acid; D013657:Taurodeoxycholic Acid