Adaptive discrimination between non-tuberculous mycobacteria by Caenorhabditis elegans.

Caenorhabditis elegans modifies its behaviour in response to bacterial cues, but its ability to distinguish between closely related environmental bacteria remains unclear. Here, we examine responses to non-tuberculous mycobacteria, the opportunistic pathogen Mycobacterium abscessus and the non-pathogenic Mycobacterium smegmatis . While Escherichia coli OP50 was the preferred choice when available, worms showed distinct, time-dependent responses to the mycobacterial species. Notably, prior exposure to M. smegmatis drove faster and stronger avoidance of M. abscessus than exposure to the pathogen itself. These findings thus show that C. elegans can rapidly and adaptively discriminate between closely related mycobacteria, highlighting how prior experience shapes behavioural decisions.