Cell effect of CFS
Several substances can be produced by the LAB used in this study,
especially organic acids (mainly lactic and acetic), hydrogen peroxide,
diacetyl, fatty acids, and different bacteriocins[15], with variations according to the medium used
for growth and the individual potential of the strains. This study
evaluated the production of CFS in MRS broth, with manganese in its
composition. This production method can result in the absence of
hydrogen peroxide, catalyzed in oxygen and water[16], thus removing a substance with high
antimicrobial activity.
Through the results, it can be seen that high concentrations of the CFS
were cytotoxic in HT-29 cells. According to Chen et al.[17], the pH of CFS results in reduced cell
viability. In addition, CFS can present high concentrations of nitric
oxide when produced in MRS broth, a highly cytotoxic compound at high
concentrations. With the reduction in the concentration of L.
plantarum 6.2 and L. plantarum 7.1 CFS, there was no change in
cell viability.
When exposed to L. fermentum 5.2 CFS, there was cell
proliferation at concentrations ≤ 10 mg/mL. Although widely studied as
antimicrobial compounds, the compounds generated by LAB, mainly fatty
acids, can cause the proliferation of several cell types. Blottiere et
al. and Balaban et al. [18,19] demonstrated that
short-chain fatty acids resulted in a proliferation of intestinal cellsin vitro and in vivo , in addition to acting on breast
tumor cells, due to their use as metabolic substrates and in the
production of growth factors.