Several reports indicated that H. pylori has the ability to form biofilms on abiotic surfaces in vitro as well as on human gastric mucosa [18–21, 23]. The results of the biofilm formation analyses demonstrated that strain TK1402 has strong biofilm forming ability compared to other strains independent of its growth rate. Development of strain TK1402 and SS1 biofilms from day 1 to day 6 demonstrated that it took 3 days for biofilm maturation under these conditions, suggesting that H. pylori biofilm formation might proceed in an organized fashion

IWP-2 mw through early (Day 1), intermediate (Day 2) and maturation (after Day 3) phases of development. Similar distinct developmental phases have been reported for biofilm formation by other bacterial species [24, 25]. Since development of biofilms is closely associated with the generation of a matrix, the majority of which is

extracellular material, biofilm development see more in H. pylori appears to share common basic steps with other biofilm forming bacteria. The biofilm forming cells at day 3 generally appeared to be viable when the cells were exposed to Live/Dead BacLight staining. In addition, the normalized CFU values for the biofilm and broth culture cells following 2 days of incubation were comparable. In 3-day biofilm cells, this value was slightly decreased compared to 3-day broth culture cells, suggesting the presence of some dead cells in the biofilm. These results are consistent with the maturation phase of the development of biofilms in 3-day biofilms of strain TK1402, since biofilms STA-9090 are thought to be encased in an EPS matrix as well as dead cells [26]. In addition, strain TK1402

exhibited thick biofilm formation. The biofilm click here morphology of strain TK1402 showed direct cell-cell bound aggregates as well as flagella-dependent binding forms. The cell-cell interacting forms might act as precursors for thick biofilm formation. Gots et al. indicated that cell-cell aggregation induces a multilayered architecture during Staphylococcus epidermidis biofilm formation [27]. Moreover, in our SEM observations, for the majority of the H. pylori strains examined, ie., SS1, biofilms may contain autolysed cells. On the other hand, there were clearly intact cells in TK1402, as well as TK1049, biofilms and the later is also another strong biofilm forming strain. These observations suggested that these strong biofilm forming strains may remain in an active metabolic state for a relatively long time without exhibiting morphological changes or autolysis, in comparison with the other strains. These later properties could be responsible for the weaker biofilm forming activities of most of the strains examined in this study. In the SEM observations of TK1402 biofilms, there were many OMV. OMV production is a physiologically normal function of gram-negative bacteria [22, 28]. It was also reported that the H. pylori strains released OMV into the extracellular space [29, 30].