Ultrastructure and adhesion properties of Ruminococcus albus

Area of Science:

• Microbiology
• Cell Biology
• Rumen Microbiology

Background:

• Rumen bacteria play a crucial role in digesting plant material.
• Ruminococcus albus is a key anaerobic bacterium found in the rumen.
• Understanding bacterial cell structures is vital for comprehending their ecological functions.

Purpose of the Study:

• To investigate the morphological characteristics of Ruminococcus albus.
• To identify and characterize the extracellular polysaccharide coat of R. albus.
• To elucidate the role of the polysaccharide coat in cell adhesion and protection.

Main Methods:

• Morphological studies using electron microscopy.
• Ruthenium red staining to visualize the polysaccharide coat.
• Freeze-etching techniques to examine surface structures.
• Observation of bacterial adhesion to cellulose fibers in vitro.

Main Results:

• R. albus cells contain electron-translucent reserve carbohydrate granules.
• A distinct polysaccharide coat surrounds the gram-negative cell wall.
• This coat forms a fibrous mat and projects radial fibers up to 0.6 µm.
• Radial fibers are visualized by freeze-etching and extend into intercellular spaces.
• The coat mediates the adhesion of R. albus to cellulose fibers.

Conclusions:

• The polysaccharide coat of R. albus is a significant structural component.
• This coat plays a dual role in mediating cellulose adhesion and providing cell protection.
• These findings enhance our understanding of R. albus ecology and function in the rumen.