you can use culture media (MRS or  M17) 

You can use  with 2% (w/w)glycerol and 5% (w/w) maltodextrin as protective

compounds.

REF

Coulibaly I., Yao A.A., Lognay G., Destain J., Fauconnier M-L, Thonart P. 2009. Survival of freeze-dried Leuconostoc mesenteroides and Lactobacillus plantarum related to their cellular fatty acids composition during storage. Appl. Biochem. Biotechnol. 157(1): 70-84.

Yao A.A. ,Wathelet B., Thonart P. 2009. Effect of protective compounds on the survival, electrolyte leakage and lipid degradation of freeze-dried Weissella paramesenteroides LC11 during storage. J. Microbiol. Biotechnol. 19: 810-817.

Please try LDL from egg yolk or skim milk with maltodextrin

thank you very much for your contributions!

Please, Adham M Abdou: some references about the optimal mixture concentration of these ingredients?

Hello Izaskun, you can use the protective agents such as skim milk, glycerol and short chain sugars. (according to Saarela, M., I. Virkajarvi, H. L. Alakomi, P. S.

Mattila, and J. Matto. 2006. Stability and functionality of freeze-dried probiotic

Bifidobacterium cells during storage in juice and milk. Internatonal Dairy

Journal.)

You can use glycerol, beta glycerophosphate, sucrose,maltodextrin, etc.

Palak Jani, Sreeja V. and Prajapati JB (2011). Influence of Different Cryoprotectants and Packaging Materials on the Viability and Acidifying Activity of Freeze-dried Streptococcus thermophilus Cultures. Ind J Dairy Sci. 64(2):112-120