Bakterienhülle

Bakterienhülle refers to the outer layers of a bacterial cell, which are crucial for its survival and interaction with the environment. These layers provide structural integrity, protect the bacterium from osmotic lysis, and play a role in adhesion and pathogenicity. The composition and complexity of the bakterienhülle vary significantly between different bacterial species, reflecting their diverse lifestyles and ecological niches.

The most fundamental component of the bakterienhülle is the cell membrane, a phospholipid bilayer that encloses the cytoplasm and regulates the passage of substances into and out of the cell. Surrounding the cell membrane in most bacteria is the cell wall. The bacterial cell wall is primarily composed of peptidoglycan, a unique polymer that provides rigidity and prevents the cell from bursting due to internal osmotic pressure. The thickness and structure of the peptidoglycan layer are key features used to classify bacteria into Gram-positive and Gram-negative types. Gram-positive bacteria have a thick peptidoglycan layer, while Gram-negative bacteria possess a thinner layer and an additional outer membrane.

The outer membrane, present in Gram-negative bacteria, is a lipid bilayer containing lipopolysaccharides (LPS) and porins. LPS is an endotoxin that can trigger immune responses in host organisms, contributing to the pathogenicity of many Gram-negative bacteria. Porins are channel proteins that allow the passage of small hydrophilic molecules across the outer membrane. Beyond these core structures, some bacteria may possess additional external layers such as capsules, slime layers, or S-layers. These glycocalyces or proteinaceous surfaces offer further protection, aid in adhesion to surfaces or host cells, and can contribute to biofilm formation. The bakterienhülle is therefore a complex and dynamic structure essential for bacterial life.