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Straightforward Assay for Quantification of Social Avoidance in Drosophila melanogaster
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Enantiomer sensing enables social avoidance by bacterial spores
Colin J Comerci1, Todd Kwang-Tao Chou1, Ramina Amino1
1Department of Molecular Biology, School of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
Iscience
|April 17, 2026
Summary
Bacillus subtilis spores use amino acid stereochemistry as a social avoidance mechanism. They avoid germination when sensing D-alanine, a molecule produced by other bacteria, protecting them from potentially harmful interactions.
Area of Science:
- Microbiology
- Biochemistry
- Ecology
Background:
- Molecular chirality's role in inter-organismal interactions is largely unknown.
- Amino acid stereochemistry, specifically L- and D-alanine, influences Bacillus subtilis spore germination.
Purpose of the Study:
- To investigate the role of amino acid stereochemistry in bacterial social interactions.
- To determine the biological significance of Bacillus subtilis spore enantiomer sensing.
Main Methods:
- Quantified L- and D-alanine concentrations secreted by over 20 bacterial species.
- Assessed Bacillus subtilis spore germination response to varying L-/D-alanine ratios.
- Utilized pairwise co-cultures to observe germination under species interaction conditions.
Main Results:
- Bacterial species secrete L-/D-alanine ratios that inhibit Bacillus subtilis spore germination.
- Bacillus subtilis spores avoid germination when exposed to enantiomer ratios from other species.
- Co-culture experiments demonstrated that germination is often detrimental in the presence of other bacterial species.
Conclusions:
- Bacillus subtilis spores utilize the L-/D-alanine ratio as a social avoidance mechanism.
- Enantiomer sensing provides a survival benefit for spores by preventing harmful inter-species interactions.
- Amino acid chirality plays a significant role in microbial ecosystems and inter-organismal communication.
Keywords:
Microbiology
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