From The American Society for Microbiology:

Exposure to specific bacteria in the environment, already believed to have antidepressant qualities, could increase learning behavior according to research presented today at the 110th General Meeting of the American Society for Microbiology in San Diego.

“Mycobacterium vaccae is a natural soil bacterium which people likely ingest or breath in when they spend time in nature,” says Dorothy Matthews of The Sage Colleges in Troy, New York, who conducted the research with her colleague Susan Jenks. …

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HT: Israel Wayne