Quorum sensing: the "switch" in the competitive relationship between Gram-positive bacteria based on transcriptomic...

Area of Science:

• Microbiology
• Bacterial Competition
• Quorum Sensing

Background:

• Bacterial competition is common, but mechanisms in Gram-positive bacteria, especially via quorum sensing (QS), are understudied.
• Understanding QS in inter-species competition is crucial for microbial ecology and biotechnology.

Purpose of the Study:

• To investigate the role of quorum sensing (QS) in the competitive interaction between two Gram-positive bacteria: Rhodococcus sp. HD1 and Microbacterium sp. HM-2.
• To elucidate the molecular mechanisms underlying QS-mediated competition.

Main Methods:

• Co-culturing of Rhodococcus sp. HD1 and Microbacterium sp. HM-2.
• Analysis of epiphysiological indicators and biomass.
• Transcriptomic analysis to identify differentially expressed genes.
• Gene engineering techniques, including gene knockout and complementation.
• Structural equation modeling to analyze gene regulatory networks.

Main Results:

• Microbacterium sp. HM-2 inhibited Rhodococcus sp. HD1 growth, altering HD1's morphology and increasing its surface-to-volume ratio.
• QS-related genes, particularly the virulence gene TM_0352, were upregulated in HM-2.
• ABC transporter genes in HD1 were upregulated, correlating with TM_0352 expression.
• TM_0352 was confirmed as a key player, promoting HM-2 biomass and inhibiting HD1 biomass.

Conclusions:

• Quorum sensing (QS) drives bacterial competition between Gram-positive bacteria through specific gene regulation.
• The TM_0352 virulence gene in Microbacterium sp. HM-2 plays a dominant role, inducing ABC transporters in Rhodococcus sp. HD1.
• These findings offer novel insights into QS-mediated competition and inhibition mechanisms between bacteria.