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SEM images confirmed these results, showing decreases in the number of cells in all biofilms. In conclusion, these findings highlight the role of farnesol as an alternative agent with the potential to reduce the Motility of Pseudomonas aeruginosa contributes to SOS-inducible biofilm DNA-damaging antibiotics such as ciprofloxacin induce biofilm formation and the SOS response through autocleavage of SOS-repressor LexA in Pseudomonas was investigated with 96-well and lipid biofilm assays. The effects of ciprofloxacin were examined on biofilm stimulation of the SOS mutant and wild-type strains. The stimulation observed in the wild-type in which SOS was induced was reduced in the mutant in which LexA was made non-cleavable (LexAN) The possible mechanisms of inducible biofilm formation were explored by subproteomic analysis of outer membrane fractions extracted from biofilms. The data predicted an inhibitory role of LexA in flagellum function. This premise was tested first by functional and morphological analyses of flagellum-based motility.

The flagellum swimming motility decreased in the LexAN strain treated tested cell migration and biofilm formation. The results showed that wild-type biofilm increased significantly over the LexAN. These results suggest that LexA repression of motility, which is the initial event in biofilm development, contributes to repression of SOS-inducible biofilm formation. [Influence of antimicrobial peptides of human thrombocytes on Staphylococcus AIM: Study the influence ofplatelet low molecular weight protein on S. aureus MATERIALS AND METHODS: 20 clinical isolates of coagulase-positive staphylococci antimicrobial peptides (fractions with molecular weight 60-70 kDa, 20-25 kDa and 5-10 kDa) obtained from human thrombocyte donors was used. Bio film formation was evaluated by separation of cell suspension in two-phase system liquid-liquid. The data obtained were treated by nonparametric method using Mann RESULTS: Platelet low molecular weight proteins (PLB) at concentration of 2 microg/ml reduced biofilm formation of S.

aureus by 48 +/- 9% from initial values, increased hydrophobicity of plankton and biofilm cell fractions. Maximum inhibitory effect of the preparation containing platelet low molecular weight proteins was noted at concentration of 50 microg/ml. CONCLUSION: The data obtained on inhibition of staphylococci BFF by platelet low molecular weight protein open a perspective of further studies of PLB as a preparation suitable for control ofbiofilm of persistent microorganisms. Environmental Adaptability and Quorum Sensing: Iron Uptake Regulation during Biofilm Formation by Paracoccus denitrificans. Paracoccus denitrificans is a valuable model organism due to its versatile respiration capability and bioenergetic flexibility, both of which are critical to its survival in different environments. Rhamnose-containing polysaccharides (QS) plays a crucial role in the regulation of many cell functions; however, whether QS systems play uptake systems in P. denitrificans were directly regulated by a newly identified QS system.

Genes coding for TonB-dependent systems, which transport chelated iron, were transcribed at higher levels in the QS-defective mutants. In contrast, genes coding for the Fbp system, which is TonB independent and QS in P. denitrificans triggers a switch in iron uptake from TonB-dependent to TonB-independent transport during biofilm formation as higher concentrations of iron accumulate in the exo polysaccharide (EPS). Switching from TonB-dependent iron uptake systems to TonB-independent systems not only prevents cells from absorbing excess iron but also conserves energy. Our data suggest that iron uptake strategies are directly regulated by QS in Paracoccus denitrificans to support their survival in available ecological niches.IMPORTANCE As iron is an important trace metal for most organisms, its absorption is highly regulated. Fur has been reported as a prevalent regulator of iron acquisition.

In addition, there is a relationship between QS and iron acquisition in pathogenic microbes. However, there have been few studies on the iron uptake strategies of nonpathogenic bacteria. In this study, we demonstrated that iron uptake systems in Paracoccus denitrificans PD1222 were regulated by a newly identified PdeR/PdeI QS system during biofilm formation, and we put forward a hypothesis that QS-dependent iron uptake systems benefit the stability of biofilms.