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Signalling helps connects different organisms in the biosphere into one integrated community by facilitating flows of metabolites, nutrients, energy, and genetic information between organisms. In particular, interactions between microbes and higher organisms are of special interest given accumulating evidence of microbial consortia’s roles in mediating various host physiological and metabolic processes in health and disease. Specifically, various studies have highlighted important ecophysiological roles of interkingdom signalling between bacteria and insects; for example, bacteria secrete odourous compounds to attract and enlist the help of blow flies for dispersal to new ecological niches. This abstract-only preprint describes the odour mediated attraction of flies to stationary phase aerobic liquid cultures of Bacillus subtilis NRS-762 (ATCC 8473) maintained on an open orbital shaker at 25 oC and 250 rpm. Specifically, odour emanation from late stationary phase culture coincided with the attraction of flies to the shake-flasks’ cotton plugs in a concentration-dependent manner. Further, observation of the flies’ more intense attempts at entering the cotton plugs’ matrix with greater odour intensity suggested possible behaviour modifying effects of the secreted compounds. Additionally, decline in optical density with increase in odour pungency suggested volatile compound(s) secretion was a nutritional stress response mediated by a feedback loop linking population size and cell survival response. Similar odour also emanated from B. subtilis cultivated at 30 and 37 oC, but the closed incubators prevented fly entry. Flies were not attracted to odourous stationary phase cultures of Escherichia coli DH5α, Pseudomonas aeruginosa PRD-10, and Pseudomonas protegens Pf-5, cultivated under identical conditions; thereby, pointing to the signalling molecules’ species-specificity. Altogether, the secreted volatile compound(s) might serve as interkingdom messengers for enlisting flies to disperse B. subtilis to habitats with more favourable nutritional and environmental conditions, while the bacteria provided the flies with physiological and metabolic functions in return. Further, interkingdom signalling might be one arm of a two-prong strategy helping to ensure bacteria population survival. Specifically, species dispersal via interkingdom signalling is a useful hedge against possible irreversible decline in a microcosm’s habitability, while other mechanisms (such as cannibalism) operate in parallel to help B. subtilis ride out short-term environmental fluctuations. Collectively, the observations highlighted possible ecophysiological roles of bacteria secreted volatile compounds in mediating interkingdom communication with flies – and opens up interesting lines of research in ecology, cell-cell signalling, stress response, and gut microbiota-host interactions
This is an abstract-only preprint. The manuscript will be submitted to a journal for review.