Microcolony scaffolding is stabilized by the formation of head-to-head dimers between Scl1 molecules on adjacent chains (pink field). Inset shows Scl1-Scl1 head-to-head dimers formed by rScl1.1 as viewed by electron microscopy after rotary shadowing [64]. Bar: 50 nm. Conclusions In the present work, using pathogenically differing GAS strains, we have demonstrated three concepts. First, we have confirmed previous observations that biofilm formation is an innate property of GAS strains. The M41-type selleckchem strain used formed a more robust

biofilm when compared to M28-type strain as well as M1-type strain. Importantly, the highly www.selleckchem.com/products/chir-99021-ct99021-hcl.html invasive M3-type strains devoid of the surface-associated Scl1 also lack the ability to form biofilm. Secondly, the absence of surface-associated Scl1 decreases GAS-cell

hydrophobicity suggesting that Scl1 plays a role on the GAS surface as a hydrophobin. Thirdly, we have established that the Scl1 protein is a significant determinant for GAS biofilm formation. This concept was further tested by the heterologous expression of Scl1 in Lactococcus, an organism found in Cell Cycle inhibitor dairy fermentation environments, enabling it to form biofilm. Altogether, these data underscore the importance of Scl1 in biofilm-associated regulation of GAS pathogenicity. Recently published work has shown that the recombinant Scl1 binds to the extracellular matrix components, cellular fibronectin and laminin [19]. Our current research provides a foundation warranting additional investigation as to CYTH4 whether direct Scl1-ECM binding may promote GAS biofilm as a bridging mechanism within host tissues. Methods GAS strains and

growth conditions The wild-type GAS strains M41- MGAS6183, M1- MGAS5005, and M28-type MGAS6143, as well as their scl1-inactivated isogenic mutants and complemented M41Δscl1 mutant have been previously described [22, 27, 65]. In addition, a set of the wild-type M3-type GAS strains MGAS158, MGAS274, MGAS315, MGAS335, MGAS1313, and MGAS2079 was also used. GAS cultures were routinely grown on brain-heart infusion agar (BD Biosciences) and in Todd-Hewitt broth (BD Biosciences) supplemented with 0.2% yeast extract (THY medium) at 37°C in an atmosphere of 5% CO2-20% O2. Logarithmic phase cultures harvested at the optical density (600 nm) of about 0.5 (OD600 ~0.5) were used to prepare GAS inocula for biofilm analysis. Colony counts were verified by plating on tryptic soy agar with 5% sheep’s blood (Remel). Lactococcus lactis subsp. cremoris strain MG1363 (provided by Dr. Anton Steen) were grown using M17 broth or agar media (Oxoid) supplemented with 0.5 M sucrose and 0.5% glucose (SGM17 media) at 30°C in an atmosphere of 5% CO2-20% O2.