Biofilm-Associated Infections

Antibiotic Resistance and Novel Therapeutic Strategies

Fengjun Sun; Feng Qu; Yan Ling; Panyong Mao; Peiyuan Xia; Huipeng Chen; Dongsheng Zhou


Future Microbiol. 2013;8(7):877-886. 

In This Article

Architecture & Physiology of Biofilms

A biofilm is an aggregate of microbial cells embedded in a self-produced matrix, which can account for over 90% of the dry mass of a biofilm,[1] on living or nonliving surfaces. The dried matrix is primarily composed of exopolysaccharide, as well as extracellular DNA, RNA, proteins and lipids.[1] Biofilms can be viewed as a protected mode of microbial growth that can provide protection from hostile environments.

The development of biofilms generally consists of five stages:[2] planktonic cells tend to attach to surfaces in a reversible manner through flagella, pili, fimbriae and polysaccharide adhesions; as microbial cells multiply, they become more firmly attached and subsequently immobilized on surfaces in an irreversible manner due to the production of extracellular matrix polysaccharides and proteins; cells grow on top of one another, begin to secrete surrounding matrix and further turn into discrete cell clusters called microcolonies; microcolonies grow in size and coalesce to form macrocolonies, a fully matured biofilm structure; and cells can disperse from macrocolonies and form a new biofilm or proliferate to be planktonic cells.

Microbial cells and their extracellular matrix in a biofilm aggregate to form a complex 3D architecture, in which groups of microbial cells are separated by open water channels that act as a primitive circulatory system for the delivery of nutrients and oxygen, and the removal of metabolic waste products.[3] The function of the above-mentioned architecture leads to the establishment of chemical concentration gradients of nutrients, waste products and secreted signaling compounds within the biofilm strata and, notably, these gradients may intersect or overlap generating many unique microenvironments within microbial biofilms.[3] Microbial cells within a biofilm differ in cell physiology and gene expression patterns to adapt to particular spatial locations within biofilms.[3]