Year: 2025
Type: article
Abstract: Passive sliding motility allows Mycobacterium smegmatis to spread over soft agar surfaces. Usually, bacterial growth and reduced surface adhesion push individual bacteria outwards, resulting in circular colonies; however, more complex, dendritic colonies have also been reported. Although we could readily reproduce the circular morphotype, our non-circular colonies (hereafter digitate colonies) differed from dendritic colonies. Digitate colonies were characterised by centimetre-long, linear protrusions consisting of surface pellicle and inner biofilm components surrounding a central channel that was filled with a free-flowing suspension of M. smegmatis and aggregates. Time-lapse microscopy showed that the expansion of the fluid-filled channel resulted in lengthwise extension of the protrusions without any perceptible bacterial growth. These observations reveal a novel type of sliding motility (named hydraulic sliding) associated with a distinct colony structure and the apparent generation of force by expansion of a liquid core. The presence of a pellicle (a floating biofilm) generated without an initial liquid-air interface suggests that a previously unknown mycobacterial behaviour that could be important for colonisation and virulence has been discovered.
Institution: University of Sheffield
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,300
OpenAlex ID: W4415645064