Flagellum-mediated motility in Pelotomaculum thermopropionicum SI

Area of Science:

• Microbiology
• Bacterial Physiology
• Molecular Biology

Background:

• The flagellum's role in motility and chemotaxis for Pelotomaculum thermopropionicum, a propionate-oxidizing bacterium, remains uncharacterized.
• Comparison with Syntrophobacter fumaroxidans, an aflagellar propionate-oxidizing bacterium, is utilized to investigate P. thermopropionicum motility.

Purpose of the Study:

• To elucidate the mechanism of motility in Pelotomaculum thermopropionicum.
• To determine if the flagellum of P. thermopropionicum is responsible for its observed motility.

Main Methods:

• Comparative motility assays in soft agar medium between P. thermopropionicum and S. fumaroxidans.
• Inhibition studies using a proton uncoupler (carbonyl cyanide m-chlorophenyl hydrazone) and an Na+ channel blocker (5-N-ethyl-N-isopropyl amiloride).
• Genetic complementation of Escherichia coli ∆motAB mutant using P. thermopropionicum motAB genes.

Main Results:

• P. thermopropionicum exhibited flagellum-dependent motility, evidenced by cell spreading in soft agar, contrasting with S. fumaroxidans.
• Motility was inhibited by a proton uncoupler, suggesting a proton-driven mechanism, and unaffected by an Na+ channel blocker.
• The P. thermopropionicum motAB genes successfully restored swimming ability to E. coli ∆motAB, confirming their functional role.

Conclusions:

• The motility of Pelotomaculum thermopropionicum is flagellum-dependent.
• The flagellar motor of P. thermopropionicum operates via a proton-driven mechanism, similar to proton-type stators.