Lyophilization is one of the most used methods for bacterial preservation. In this process, the cryoprotectant not only largely decreases cellular damage but also plays an important part in the conservation of viability during freeze-drying. This study investigated using cryoprotectant and a mixture of the cryoprotectant to maintain probiotic activity. Seven probiotic strains were considered: (Limosilactobacillus reuteri KUKPS6103; Lacticaseibacillus rhamnosus KUKPS6007; Lacticaseibacillus paracasei KUKPS6201; Lactobacillus acidophilus KUKPS6107; Ligilactobacillus salivarius KUKPS6202; Bacillus coagulans KPSTF02; Saccharomyces cerevisiae subsp. boulardii KUKPS6005) for the production of a multi-strain probiotic and the complex medium for the lyophilized synbiotic production. Cholesterol removal, antioxidant activity, biofilm formation and gamma aminobutyric acid (GABA) production of the probiotic strains were analyzed. The most biofilm formation occurred in L. reuteri KUKPS6103 and the least in B. coagulans KPSTF02. The multi-strain probiotic had the highest cholesterol removal. All the probiotic strains had GABA production that matched the standard of γ-aminobutyric acid. The lyophilized synbiotic product containing complex medium as a cryoprotectant and wall material retained a high viability of 7.53 × 10⁸ CFU/g (8.89 log CFU/g) after 8 weeks of storage. We found that the survival rate of the multi-strain probiotic after freeze-drying was 15.37% in the presence of complex medium that was used as high performing wall material. Our findings provided a new type of wall material that is safer and more effective and, can be extensively applied in relevant food applications.

One of the most prominent pigments found in nature, carotenoids are employed extensively in the cosmeceuticals, pharmaceuticals, food industries, and feeding sectors in addition to phytomedicine. Recently, microbial synthesis of products has gained popularity in various industrial sectors. The economic and environmental aspects of microbial carotenoid production have attracted a lot of attention. The aims of this research were to investigate the potential of novel yeast, Occultifur sp. M2004 for carotenoids production, identify the pigment structure and evaluate the anti-collagenase and anti-elastase properties of pigments produced by a newly isolated yeast. Antibiotic susceptibility tests revealed that this strain was sensitive to colistin and gentamicin but resistant to co-trimoxazole, vancomycin, gentamicin, amoxiclav, doxycycline, ampicillin, and cefalexin. The optimal conditions for yeast growth and red pigmentation were achieved by cultivating in yeast extract-glucose (YG) medium at pH 6, 25 °C with agitation at 150 rpm for 7 d. Beta-carotene was identified as the produced pigment using Fourier transform infrared spectroscopy (FT-IR) technique and liquid chromatography-mass spectrometry (LC-MS) analysis. The half maximum inhibitory concentration (IC50) values for anti-collagenase and anti-elastase activities were 2.61 μg/mL and 100.16 μg/mL, respectively. This study highlights the potential of Occultifur sp. M2004 as a valuable and versatile resource for producing carotenoids, which could have potential applications in nutraceuticals.