Figure 1.
SLS-dependent cytotoxicity of S. anginosus subsp. anginosus against human oral squamous cell carcinoma cell line HSC-2 under co-cultivation condition. HSC-2 was co-cultivated with higher cell-density (OD600 = 0.1) (a), the magnified picture of white square is shown as (b); and moderate cell-density (OD600 = 0.01) (c), the magnified picture of white square is shown as (d) of β-hemolytic S. anginosus subsp. anginosus (SAA) strain NCTC10713T. HSC-2 was also co-cultivated with higher cell-density (OD600 = 0.1) of non-hemolytic SAA strain NCTC11169 (e). Image (f) shows the intact HSC-2 without the co-cultivation with bacteria. The morphological observation was carried out using the inverted microscope IX71 (Olympus) equipped with DP72 (Olympus) after removal of the bacterial cells. The scale bar shows 50 μm. The viability of the HSC-2 cells was also evaluated using CCK-8 (g). The results are shown as the percentage of viability with standard deviation (SD) to 100% viable control of HSC-2 without co-cultivation with bacteria (n = 3). The significance of the differences in the results from the cultivation without bacteria (w/o) was evaluated by Student’s t-test or Welch’s t-test after F-test using the software R (**p < 0.01, *p < 0.05, and “ns“ indicates ”not significant”).