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Updated: Jul 30, 2026

Monitoring Intraspecies Competition in a Bacterial Cell Population by Cocultivation of Fluorescently Labelled Strains
Published on: January 18, 2014
Interactions between gramicidin S and its producer, Bacillus brevis
1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Abstract:
Gramicidin S (GS) inhibition of germination outgrowth of Bacillus brevis spores was reversed completely by a short pretreatment with sodium dodecyl sulfate, moderately by ethanol or by incubation at pH 10 but not by incubation at pH 4. Of five metal ions tested (Na+, Mg2+, Fe2+, Cu2+, Ca2+), only Ca2+ reversed GS inhibition. When Ca2+ (but not the other four metal ions) was added to the growth medium, there was a considerable portion of the biosynthesized GS found in the extracellular fluid. These findings are interpreted in terms of the binding of GS to the external layers of the B. brevis spore.
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