## 2 Bioferments
### Biological Activity of Bacterial Ferment Filtrate
#### 2.4.3 Strengthening and Protection of the Skin Barrier  
[PERSON] et al. [43] investigated the influence of _Bifidda_ fermentation lysate (obtained by fermentation and extraction of _Bifidobacterium_) on the skin barrier using in vitro models. Application of the lysate increased the level of the skin's barrier gene (_FLG_, _LOR_, _IVL_, _TGM1_, and _AQP3_) and the antimicrobial peptides gene (_CAMP_ and _hBD_-2) in human HaCaT cells. Thus, _Bifida_ fermentation lysate may be responsible for skin barrier resistance. In antioxidant tests, such as DPPH, ABTS, hydroxyl, and superoxide radical scavenging activity assay, studied lysate showed dose-dependent radical scavenging ability. Moreover, the inhibition of intracellular production of ROS and MDA in HaCaT cells was reported. _Bifida_ fermentation lysate also reduced the secretion of IL-8 and TNF-\(\alpha\) and gene expression level of cyclooxygenase-2 (COX-2) in THP-1 macrophages [43]. Studies on the effect of _Vitreousilla filiformis_ bacterial lysate on the normal human epidermal keratinocytes (NHEK) confirmed improvement in the skin barrier function through the increasing the level of tight junction proteins, such as filaggrin, involucrin, claudin-1, and zonula occludens-1 in NHEK cells [44]. Studies showed that, after the addition of _Saccharomyces_ germplasm filtrate, keratinocytes had higher expression of tight junction proteins, which determined tissue homeostasis. In keratinocytes treated with studied ferment mRNA and proteins levels of claudin-1, claudin-3 and 4, occludin and ZO-1 were increased. The increase in the value of TER (transepithelial electrical resistance) confirmed the influence of studied ferment on the barrier function of the epidermis. The studies confirmed that _Saccharomyces_ germplasm filtrate improve the condition of skin by modulating and strengthening the skin barrier function [45]. [PERSON] et al. [25] performed tests on lysates of _Lacticaseibacillus rhamnus_ VHProbi\({}^{\text{\textregistered}}\) E06 (E06) and _L. Paracasei_ VHProbi\({}^{\text{\textregistered}}\) E12 (E12) and reported the protective effect on HaCaT cell viability. _S. aureus_ ATCC 25923, H\({}_{2}\)O\({}_{2}\), and ultraviolet-B (UVB) radiation were used to induce the deterioration of cell viability. Both lysates increased proliferation and reduced toxicity caused by the previously mentioned factors. Subsequently, the lotion formula with four fermented lysates (E06, E12, _Lactiplantiobacillus plantarum_ VHProbi\({}^{\copyright}\) E15, and _Lacto-bacillus helveticus_ VHProbi\({}^{\copyright}\) Y21) were prepared. Lotion containing 3% tested lysates was used in clinical trials (on 52 participants). The assessment was carried out with VSIA\({}^{\copyright}\)-CR (Canfield Scientific Inc, Parsippany, NJ, USA) and CK\({}^{\copyright}\)-MPA (Courage+Khazaka electronic GmbH, Koln, Germany) devices. In addition, Burden of Sensitive Skin questionnaire (BoSS) and self-assessment questionnaire were performed. Data from the study showed that at day 30, there was a significant decrease in TEWL, redness, and increase in hydration compared to baseline measurements. BoSS and self-assessment questionnaires also substantiated that the studied subjects noticed positive change in their skin condition [25]. Clinical trials have been conducted on ferment lysates of _Lacticaseobacillus rhamnus_ IDCC 3201. This study aimed to determine whether the cream containing the bacteria ferment lysate improves the barrier function of the skin. The study was performed on 24 women aged 20-70. The TEWL and the skin hydration tests were performed and the beneficial effects for skin barrier function were confirmed. In patient surveys, respondents also positively assessed the improvement in skin hydration [26]. [PERSON] et al. conducted a study on the protective effect of a cream with a noisiturizer containing a _Galactomyces_ ferment filtrate on the skin. Mask wearing to protect against COVID-19 caused various facial skin damage. A total of 20 women participated in the study.