Swarming motility in undomesticated Bacillus subtilis.

Area of Science:

• Microbiology
• Bacterial Motility

Background:

• Swarming motility is a complex, coordinated surface movement exhibited by many bacteria.
• Bacillus subtilis is a well-studied bacterium, but its swarming capabilities in undomesticated strains are less understood.
• Laboratory strains of Bacillus subtilis are often used in research but may have lost certain wild-type behaviors.

Purpose of the Study:

• To identify and characterize swarming motility in an undomesticated Bacillus subtilis strain.
• To investigate the requirements for swarming motility, including cell density, flagella, and surfactant production.
• To compare the swarming ability of undomesticated strains with standard laboratory strains.

Main Methods:

• Observation and characterization of surface migration in Bacillus subtilis.
• Analysis of cell density-dependent lag periods and inoculum effects.
• Microscopic examination of multicellular rafts at the swarm edge.
• Genetic and biochemical assays for flagellum biosynthesis and surfactant production.
• Extracellular complementation experiments.

Main Results:

• Swarming motility was observed in an undomesticated Bacillus subtilis strain, preceded by a cell density-dependent lag phase.
• The leading edge of swarms consisted of multicellular rafts with highly flagellated cells.
• Flagellum biosynthesis and surfactant production were essential for swarming.
• Standard laboratory strains of Bacillus subtilis did not exhibit swarming motility.
• Laboratory strains, unable to produce surfactant, did not regain swarming ability even with external surfactant.

Conclusions:

• Robust swarming motility is a characteristic of undomesticated Bacillus subtilis.
• Laboratory strains have lost or attenuated swarming behavior due to accumulated genetic defects.
• Surfactant production is a critical factor for swarming in Bacillus subtilis, and its loss impacts laboratory strains significantly.