English immunologists Christopher Lowry and Graham Rook claim that a widely spread and harmless soil bacterium Mycobacterium vaccae contains some substance rising mood. They injected killed and ground by ultrasonic bacteria into mice’s trachea. As a result the mice’s brains increased producing serotonin –  biologically active substance rising mood. Medicines against depression are aimed either at enhancing serotonin synthesis or at moderating its decomposition. Mice who got the portion of serotonin were more active and lively.

The researchers say that one can breathe in a dose of bacteria when walking through a forest, garden or field which will raise his spirits. They point out that it’s hard to predict yet whether the curing substance can be elicited from bacteria or physicians will simply be prescribing ingestion of bacteria.