**4.2 Antibacterial activity**

The tests of antibacterial properties of flax fibers were conducted with a fluorescent method using strains of the clinical bacteria *Staphylococcus aureus* isolated from ill people [31].


*a represents the group for which the mean values do not differ statistically at the assumed significance level. The mean values labeled with the same letter (a) do not differ statistically at (α = 0,05).*

#### **Table 3.**

*The antioxidative activity of different varieties of bast fibers depending on the extraction method. Results are expressed as mean wf standard deviation (SD), n = 3. Lowercase letters indicate significant differences at p ≤ 0.05 according to the Tukay's HSD test [19].*

Test conditions:


*S. aureus* belongs to the most common etiological factors of inflammation in surgical places. The evaluation of bacteria viability was performed using the Bacterial Viability Kit (Molecular Probes).

The images presented in **Figures 6** and **7** show the fibers and strains of the clinical bacteria *S. aureus* isolated from ill people after 90 minutes of incubation. The orange particles on the fiber surface illustrate killed bacteria. It is visible that killed bacteria are located only in direct contact with the fibers.

The study [31] on the antibacterial activity of flax covered five varieties: Artemida, Modran, Sara Nike, and Luna. The extracted fibers with use of dew retting or water retting method were tested in order to evaluate their ability to reduce colonies of *S. aureus bacteria*. The results confirmed that the fiber antibacterial capacity is strongly related to plant variety and the applied extraction method, which have effect on fibers chemical composition, mainly content of lignin cross-linked with phenolic compounds. Percentage differences in the antibacterial capacity of all types of flax fibers are shown in **Figure 8**.

Dew-retted flax fibers coming from all tested plant varieties showed stronger capacity to reduce *S. aureus* bacterial colonies than water-retted fibers. This resulted from the fact that some types of phenolic acids, for example, ferulic acid, are water soluble and have been removed during the water-retting process.
