# Ecological Prevalence and Non-Enzymatic Formation of Imidazolium Alkaloids on Moon Snail Egg Collars

## TL;DR

This study explores how moon snail egg collars contain imidazolium alkaloids formed without enzymes, which inhibit bacterial growth.

## Contribution

The study reveals the non-enzymatic formation of imidazolium alkaloids in moon snail egg collars and their ecological prevalence.

## Key findings

- Eight bacterial pairings showed growth-inhibitory activity in moon snail egg collars.
- Bacillimidazoles A and E were isolated and shown to form spontaneously from specific precursors.
- Bacillimidazole A was detected in 62% of moon snail egg collars via mass spectrometry.

## Abstract

Microorganisms wage constant chemical battles against one another as they compete for space and scarce nutrients, particularly within animal-associated habitats. Here, binary assays were used to investigate chemical interactions among Flavobacteriaceae within Neverita delessertiana egg collars, a moon snail common to the Gulf Coast. Analysis of 140 distinct pairings revealed eight that exhibited growth-inhibitory activity. Chemical evaluation of the crude extract from Cellulophaga omnivescoria EM610, which inhibited the growth of three other Flavobacteriaceae, resulted in the isolation of bacillimidazoles A (1) and E (2), two previously characterized metabolites, isolated from a marine Bacillus species. Further work demonstrated that these compounds are readily formed spontaneously by condensation of 2,3-butanedione with phenethylamine and/or tryptamine. Tandem mass spectrometry analysis of the chemical extracts of individual moon snail egg collars revealed the presence of bacillimidazole A in 62% of the egg collars.