Molecular Aspects of Biofilm

Biofilms occur extensively in aquatic engineering systems, where they are implicated mainly in biofouling and corrosion. Biofilm cause nosocomial infections by forming persistent growth in catheters and other body implants and medical devices; they also increase drug resistance and dental caries (Donlan, 2001). On the other hand, biofilm development followed by biofouling in cooling water system causes serious blocking of the coolant pipelines in power plants thereby increased load on pumps, microbial induced corrosion and substantial economic loss (Boffardi, 2005; Flemming, 2002; Oliveira, et al, 1993 and Rao et al. 1993). In waste treatment systems such as trickling filters, wet biofilms are used for catalyzing pollutant transformations (Wyndham, 1995).

Microbial world is extremely diverse and so is their life style and adaptation to survive in any environment (Staley et al, 1997). Different bacteria acquire different mechanism to adhere and initiate the biofilm development depending upon their environment. Some bacteria use their pili or flagella to establish primary attachment (Virji et al. 1993). In the present work we investigated the role of a surface protein (Bap) in S. aureus in establishing biofilm on glass surface and the topological changes in response to Ca2+ concentration from 1 mM to 20 mM on the biofilm morphology. Earlier work by Arrizubieta et al. (2004) showed that expression of Bap is not affected in presence of Ca2+. We provide information on changes in surface protein mediated growth in the presence of various concentrations of Ca2+. Calcium is an environmental variable which influence the biofilm formation of certain bacteria (Geesey et al. 2000; Patruchan et al. 2005).

In a previous report Arrizu...

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...erent environment containing varying calcium concentrations.

Conclusions:

From the present investigation we established the following salient points;

(1) Bap mediated biofilm development in S. aureus V329 is inhibited  5 mM Calcium (2) Other bap negative strains of S. aureus, SA7 and SA33 do not show any inhibition due to the presence of calcium even up to 50 mM. (3) Structurally similar BapA harbouring A. baumannii did not show any inhibition in biofilm formation in response to calcium. (4) CSLM study showed that varying Ca2+ concentrations significantly influenced the architecture and topology of the biofilm. CSLM study also shows that chelating of calcium by EDTA can inverse the effect calcium on biofilm development. (5) This study also specifies that the presence EF hand motif in Bap makes V329 strain responsive to Ca2+ presence in the milieu.