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Bacillus subtilis isolated from the human gastrointestinal tract
Huynh A Hong1, Reena Khaneja, Nguyen M K Tam
1School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey, UK.
Research in Microbiology
|December 11, 2008
Summary
Bacillus subtilis, a common soil bacterium, has been found to thrive in the human gastrointestinal tract (GIT). This study identifies Bacillus subtilis as a potential gut commensal, challenging its traditional classification.
Area of Science:
- Microbiology
- Human Gut Microbiome Research
Background:
- Bacillus species are traditionally considered soil microorganisms.
- The true habitat and role of Bacillus species in the human body remain under investigation.
Purpose of the Study:
- To investigate the presence and characteristics of Bacillus subtilis within the human gastrointestinal tract (GIT).
- To determine if Bacillus subtilis has adapted to a life within the GIT.
Main Methods:
- Isolation of Bacillus subtilis from human ileum biopsies and fecal samples.
- Biotype definition and characterization of isolates.
- 16S rRNA gene sequencing for phylogenetic analysis.
- Random Amplified Polymorphic DNA (RAPD)-PCR for genetic diversity assessment.
Main Results:
- Bacillus subtilis was successfully isolated from the human GIT.
- 16S rRNA analysis showed conserved B. subtilis strains, while RAPD-PCR revealed significant genetic diversity (23 types).
- Most isolates exhibited advantageous survival traits for the GIT, including biofilm formation, anaerobic sporulation, and antimicrobial secretion.
- A novel finding was the presence of an exosporium on B. subtilis spores from one isolate.
Conclusions:
- Bacillus subtilis is present and adapted to the human gastrointestinal tract.
- The findings support the view of B. subtilis as a gut commensal, not exclusively a soil organism.
- Further research into Bacillus species' adaptation to the GIT is warranted.
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