The bacterium Bactillus subtilis can survive various unfavorable conditions by forming a biofilm. This is enabled by production of extracellular polymeric substances (EPS), which connect the cells in the biofilm. Major B. subtilis components are polysaccharide EpsA-O, protein TasA and extracellular DNA. By growing recombinant strain of B. subtilis NCIB 3610 strain that is highly productive in EpsA-O, recombinant strain of Escherichia coli that overproduces TasA and wild type B. subtilis NCIB 3610 for DNA isolation, we obtained all the major EPS components for synthetic biofilm assembly. With the floating biofilm (pellicle) formation test using different EPS defective B. subtilis mutants, we found that our EPS isolates retained biological activity. By analyzing the composition of native biofilms we found that the largest proportion of EPS is represented by EpsA-O, then TasA and the least by DNA. During the rheological test of synthetic biofilms we found that interaction between EpsA-O and TasA contributes the most to the biofilm mechanical properties. With synthetic biofilm with all EPS components we achieved same visco-elastic values as the native homogenized biofilm but by a factor of 2 lower values than the native biofilm. Congruently, the microscopic examination showed a greater similarity of the synthetic biofilm to the homogenized than to non-homogenized native biofilm.
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