applied sciences  
Article  
Probiotics-Loaded Microspheres for Cosmetic Applications  
[PERSON] 1,*  
[PERSON] 2  
[PERSON] 2  
[PERSON] 1  
[PERSON] 1,*  
* Corresponding: [EMAIL_ADDRESS] (A.L. ); [EMAIL_ADDRESS] (E.S.) Footnote 1: [[https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci)]([https://www.mdpi.com/journal/applsci](https://www.mdpi.com/journal/applsci))  
Footnote 2: [[https://www.mdpi.com/journals/applsci](https://www.mdpi.com/journals/applsci)]([https://www.mdpi.com/journals/applsci](https://www.mdpi.com/journals/applsci))  
Footnote 3: [[https://www.mdpi.com/journals/applsci](https://www.mdpi.com/journals/applsci)]([https://www.mdpi.com/journals/applsci](https://www.mdpi.com/journals/applsci))  
Footnote 4: [[https://www.mdpi.com/journals/applsci](https://www.mdpi.com/journals/applsci)]([https://www.mdpi.com/journals/applsci](https://www.mdpi.com/journals/applsci))  
Footnote 5: [[https://www.mdpi.com](https://www.mdpi.com)]([https://www.mdpi.com](https://www.mdpi.com))  
molecules of D-mannuronic and L-galuronic acid connected by a glycosidic bond [13; 14; 15; 16]. Most of the scientific literature focuses on the application of alginate microparticles in food applications, pharmaceutical applications [13; 17; 18; 19] and recently also in environmental applications [20]. However, their potential for use in cosmetic formulations is a scientific area that needs to be explored. Among other options, active ingredients enclosed in alginate microparticles may be live strains of both predatory bacteria with an antimicrobial potential (_Bdellovibrio bacteriorovorus_) [21; 22], as well as probiotics [23; 24; 25]. _Lactobacillus casei_ is a probiotic bacterium that is known for its potential health benefits, including its role in promoting skin health. _L. casei_ may contribute to the maintenance of the skin barrier by enhancing the production of ceramides and other lipids which play a crucial role in skin integrity and help protect the skin against moisture loss, which is essential for its elasticity and comfort [26; 27]. Probiotics may exert anti-inflammatory effects by inhibiting the toxic effects of certain pathogenic bacteria on the skin, which could be beneficial for inflammatory skin conditions [28]. Some studies suggest that probiotics, including _Lactobacillus casei_, may offer protection against the harmful effects of UV radiation, potentially reducing the risk of photoaging [29]. _Lactobacillus casei_ is often associated with promoting gastrointestinal health. It may contribute to the balance of the gut microbiota and help maintain a healthy digestive system [30]. Some studies suggest that _L. casei_ may play a role in modulating the immune system, potentially enhancing its response to various challenges, such as those associated with vaccinations [31]. Additionally, _L. casei_ is a strain of bacteria commonly employed in food fermentation processes, such as the production of probiotic dairy products, including yogurts and fermented milks, where it contributes to both health benefits and the development of desirable product characteristics, enhancing both flavour and texture [32]. A probiotic strain is commonly used in the production of supplements, providing a convenient way for individuals to incorporate beneficial bacteria into their diet for potential health benefits [33]. In our previous studies, the production process of probiotic bacteria-loaded alginate microspheres was optimised. The most important process parameters affecting both the quality of the alginate microspheres and the efficiency of the encapsulation of probiotic bacteria were selected using the method of experimental design (DOE) [10]. The aim of our current study was to provide evidence that the microencapsulation process can overcome the problem of the incompatibility of probiotic bacteria with cosmetic preservatives and can also enhance the viability of probiotic bacteria inserted into skin care products.