Biofilm formation maturation

A four-stage model has been used to describe the development of a bacterial biofilm. The stages comprise, first, primary attachment of cells to the underlying biomaterial, second, accumulation in multiple bacterial layers, third, maturation of the biofilm, and fourth, detachment of planktonic cells from the biofilm, which may then initiate a new cycle of biofilm formation elsewhere [11], In the staphylococci clear evidence exists for the attachment and accumulation/maturation stages of the biofilm model [12] (Fig. 1), while active detachment mechanisms are not well... 

Interestingly, chromosomal DNA released from bacterial cells (extracellular DNA/eDNA) has been shown to support Pseudomonas aeruginosa biofilm development [43], DNAse I inhibited nascent biofilm formation, and when added to established but still young biofilms disintegrated them to some extent, whilst the effect on mature (>82 h) biofilms was not as marked. The findings indicate a role for eDNA in early P. aeruginosa biofilm development [43],... 

Because of complex effect of pipe material, water quality and flow velocity on the biofilm in the studied water distribution system, the biofilm formation process was studied in a model system. It was determined the highest bacterial density of the biofilm developed on carbon steel and the lowest ones of the biofilms on plastic pipes (Fig. 2). The results showed strong influence of the pipe material on biofilm density during initial phases of the process compared with mature biofilm. 

Conditioning iayer Baoteriai attachment Biofiim formation Exopoiysaooharide Biosynthesis I Biofilm maturation t i r j i Disiodgement Detachment... 

Fig. 1 Biofilm development and regeneration illustrated in six steps. Step 1 initial attachment to substratum Step 2 synthesis of EPS to establish more secure association with substratum Step 3 bacterial replication on the substratum and microcolony formation Step 4 formation of mature biofilm Step 5 sloughing and detachment of portions of biofilm Step 6 recolonization of areas of substratum exposed by sloughing events [5].

After attachment, microorganisms produce adhesive substances, collectively known as extracellular polymeric substances (EPS), which provide the matrix that holds bacteria together and allows formation of microcolonies and ultimately a mature biofilm. EPS also bridge microbial cells with the substratum and permit negatively charged bacteria to adhere to both negatively and positively charged surfaces. 

Biofilm maturation with formation of EPS, which serves to protect bacteria from biocides, flow shear, and predators. ... 

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