Biofilms, Conjugation, and Microbial Community Interactions

Vocabulary flashcards covering key concepts from the notes on biofilms, conjugation, and microbial community interactions.

Pilus (sex pilus)

A filamentous appendage used by bacteria to attach to another cell and transfer DNA during conjugation (bacterial sex).

Conjugation

Horizontal gene transfer between bacteria via a donor and recipient connected by a sex pilus.

Fimbriae

Thin, hair-like projections on the bacterial surface that mediate initial attachment to surfaces or other cells.

Biofilm

A structured community of microorganisms attached to a surface and embedded in a self-produced extracellular polymeric substance (EPS).

Initial attachment

The reversible early step of biofilm formation where cells attach to a surface through surface structures such as flagella or fimbriae.

Exopolysaccharide (EPS)

The extracellular polymeric matrix produced by biofilm cells that cements cells to the surface and to each other, enabling irreversible attachment.

Irreversible attachment

The phase in which cells become permanently anchored in the biofilm due to EPS production.

Biofilm channels

Networks of water-filled channels within a biofilm that distribute nutrients and remove waste, creating microenvironments.

Oxygen gradient in biofilms

Spatial variation in oxygen concentration, with higher oxygen near the exterior and lower oxygen inside, supporting aerobic metabolism outside and anaerobic metabolism inside.

Quorum sensing

A cell-density dependent communication system in microbial communities that uses signaling molecules to coordinate gene expression and behavior.

Autoinducer

A signaling molecule secreted by bacteria whose concentration reflects cell density and regulates gene expression in quorum sensing.

Aerobic metabolism

Metabolic processes requiring oxygen, typically occurring in the outer, oxygen-rich regions of a biofilm.

Anaerobic metabolism

Metabolic processes that do not require oxygen, occurring in the inner, oxygen-poor regions of a biofilm.

Biofilm on medical devices

Biofilm formation on artificial surfaces like implants or damaged valves, making infections difficult to treat and often requiring surgical removal or debridement.