## 4 Discussion
### Probiotic Bacterial Encapsulation as a Method of Protection from External Factors
The microencapsulation process significantly increased the survival of probiotic bacteria, and the preparations showed a 1.3-1.7 log decrease in the number of CFU in cells with a survival rate of 82-86% [42]. Both the effects of preservatives and UV light can damage bacterial DNA, depending on the wavelength and exposure time [54]. [PERSON] et al. [43], in their studies, showed that a 6 h exposure of probiotic bacteria of the species _Bacillus subtilis_ and _Bacillus licheniformis_ to UV radiation caused their almost complete elimination in aqueous solutions. There is relatively little information in the literature on the use of various methods of encapsulation of microorganisms or their spore forms as protection against the harmful effects of UV radiation. The results of our studies have shown that the use of alginate microspheres as the probiotic bacteria protection carriers significantly reduced the effect of harmful UVB radiation, with a wavelength of 311 nm. Even longer exposures (24 h and 48 h) to UVB radiation did not result in a significant reduction in the number of _L. casei_ cells (0.14 log after 24 h and 0.50 log after 48 h). Our results seem to be consistent with those of [PERSON] et al. [37], who showed that from polymers such as starch, gelatine and sodium alginate used as coating materials, sodium alginate exhibited the best protective properties. Sodium alginate protected _Bacillus thuringiensis_ spores to the greatest extent against the adverse effects of UVB and UVC radiation. Sodium alginate at all tested concentrations (2, 3 and 5%) allowed the viability of _Bacillus thuringiensis_ spores to be maintained at the level of 72-90 after the exposure of microcapsules with live spores to ultraviolet radiation over the long term (UVB), for 24-168 h, while the viability of free spores of _B. thuringiensis_ decreased to 40-70 during the time periods studied. However, at a concentration of 5%, sodium alginate enabled the viability of bacterial spores to remain unchanged at 80%, even after irradiation with ultraviolet light (UVC) over the short term for 5-25 min. The exposure of spores not protected with any coating material to the same conditions (UVC, time of 5-25 min) reduced their viability to 40-80%. In the case of our studies on the developed bacteria carriers, the efficiency of the alginate microcapsules in enhancing the survival parameters of bacterial cells were dependent on water content and were significantly lower in the case of the microdispersion in comparison with the isolated microspheres. The reduction in the water content in probiotics-loaded systems is the simplest way to increase the viability of microencapsulated LAB [10]. Among the developed systems, the most effective ones were the microspheres obtained after the separation of microcapsules from the solution with the use of centrifugation at 500 rpm. These alginate systems were applied as the active ingredients of the prepared probiotic cosmetic formulations. Effect of Preservation System Properties on the Viability of Probiotic Bacteria in Probiotic Cosmetic Products  
The microbiological purity of cosmetics and resistance to infections is a complex problem that is determined by the following factors: the quality and purity of ingredients (especially the quality of water); the hygiene of the technological process (organization of production and cleanliness of the devices used); the physicochemical properties of the final product; the type of the packaging and packaging materials; and the presence of microbial inhibitors, i.e., preservatives [55]. Regulation (EC) No. 1223/2009 of 30 November 2009 [38] describes the requirements of the safety of cosmetic products. Among other stipulations, there are requirements regarding the microbiological purity of cosmetics. In order to obtain cosmetics of appropriate quality, various types of preservatives are used in products. Preservatives are ingredients added to cosmetics to protect the consumer and prevent microbiological contamination during normal and expected use of the cosmetic product.