生物膜

A biofilm is a microbial consortium embedded in a self-produced polysaccharide matrix attached to a surface. These complex communities develop multilayered structures containing water channels for nutrient and waste transport. The matrix protects microorganisms from environmental stresses, including antibiotics and immune responses, enabling the community to persist in hostile conditions.

Biofilm formation occurs through attachment, colonization, development, and dispersal. During attachment, planktonic cells adhere to a surface. In colonization, cells produce extracellular polysaccharides forming a sticky matrix. Maturation develops the multilayered structure, while dispersal allows cells to detach and colonize new surfaces, enabling biofilm expansion.

Biofilms resist antibiotics and immune responses through their multilayered polysaccharide matrix, which limits drug penetration and reduces metabolic activity within the structure. This protective architecture allows microorganisms to evade immune system attacks and persist in infections. The matrix essentially creates a barrier that shields cells from external threats.

Quorum sensing enables bacteria to coordinate behavior through secretion of signaling molecules, leading to cell aggregation during biofilm attachment. This cell-to-cell communication mechanism facilitates the transition from free-swimming planktonic cells to organized biofilm communities. Understanding quorum sensing is essential for developing interventions against biofilm formation.

Biofilms cause significant health problems including obstruction of airways in cystic fibrosis patients, typically caused by Pseudomonas aeruginosa. Dental plaques formed by Streptococcus mutans lead to tooth decay. On medical devices like catheters, biofilms trigger persistent infections due to their resilience against antibiotics and immune defenses.

Biofilms contribute to nutrient cycling by breaking down organic matter in the environment. They are instrumental in wastewater treatment through pollutant degradation, helping remove contaminants from water systems. These ecological roles demonstrate that biofilms have beneficial applications beyond their pathogenic effects in medical and industrial contexts.

Prevention strategies include using lactoferrin, which inhibits bacterial aggregation by binding iron and reducing cell adhesion. Antimicrobial surfaces are being designed to minimize biofilm attachment. Research continues to explore molecular mechanisms to develop more effective interventions, particularly by studying factors influencing microbial growth that may suppress biofilm development.