A probiotic cell extract of a bacterial stain belonging to the genus Bifidobacterium, the species Bifidobacterium animalis subsp. lactis and identified as Bifidobacterium animalis subsp. lactis BS01 (LMG P-21384), wherein said probiotic cell extract comprises or, alternatively, consists of peptidoglycans and wherein it is obtainable according to an extraction method comprising or, alternatively, consisting of the following steps: suspending the lyophilised bacterial strain in water with a dilution bacteria:water=1:4 to form an homogeneous suspension of bacterial strains of step; transfering the homogeneous bacterial suspension of step into a jar of a blender maintaining the liquid at the level of the blender blades, and crushing the suspension of step by means of the blender to form a suspension of crushed bacterial strains; carrying out 2 crushing cycles of 1 minute each, with a 1 minute pause in between; adding 1 teaspoon of crushed ice in the blender to decrease the temperature of the preparation; collecting the suspension in a beaker and repeating the operation until all the bacteria of the suspension of step have been crushed to give a suspension of step; centrifugating the suspension of step and separating a sediment comprising intact bacteria from a supernatant of step comprising wall fragments of the bacterial strain; (III.bis) collecting only the supernatant of step in a beaker, centrifugating and separating a supernatant from a sediment of step (III.bis) comprising the peptidoglycan fractions. resuspending the sediment of step (III.bis) in water to form a suspension of step comprising the peptidoglycan fractions; adding under stirring to the suspension of step a saturated solution of ammonium sulphate [(NH 4) 2 SO 4] until 40% saturation and placing the obtained mixture at 4 °C overnight to obtain a mixture of step comprising a precipitate comprising or, alternatively, consisting of the peptidoglycan fractions; centrifugating the mixture of step, collecting a precipitate comprising the peptidoglycan fractions and eliminating the supernatant containing the ammonium sulphate; repeating phase until elimination of ammonium sulphate still present in the mixture to give a precipitate of phase comprising the peptidoglycan fractions; resuspending the precipitate of phase in water and lyophilising, wherein - in step the centrifugation of the suspension of step is performed at 900xg for 5 minutes; and - in step (III.bis) the centrifugation of the supernatant of step is performed at 10000xg for 15 minutes or at 6000xg for 20 minutes; and - in step the centrifugation of the mixture of step is performed at 10000xg for 15 minutes or at 6000xg for 20 minutes. suspending the lyophilised bacterial strain in water with a dilution bacteria:water=1:4 to form an homogeneous suspension of bacterial strains of step; transfering the homogeneous bacterial suspension of step into a jar of a blender maintaining the liquid at the level of the blender blades, and crushing the suspension of step by means of the blender to form a suspension of crushed bacterial strains; carrying out 2 crushing cycles of 1 minute each, with a 1 minute pause in between; adding 1 teaspoon of crushed ice in the blender to decrease the temperature of the preparation; collecting the suspension in a beaker and repeating the operation until all the bacteria of the suspension of step have been crushed to give a suspension of step; centrifugating the suspension of step and separating a sediment comprising intact bacteria from a supernatant of step comprising wall fragments of the bacterial strain; (III.bis) collecting only the supernatant of step in a beaker, centrifugating and separating a supernatant from a sediment of step (III.bis) comprising the peptidoglycan fractions. resuspending the sediment of step (III.bis) in water to form a suspension of step comprising the peptidoglycan fractions; adding under stirring to the suspension of step a saturated solution of ammonium sulphate [(NH 4) 2 SO 4] until 40% saturation and placing the obtained mixture at 4 °C overnight to obtain a mixture of step comprising a precipitate comprising or, alternatively, consisting of the peptidoglycan fractions; centrifugating the mixture of step, collecting a precipitate comprising the peptidoglycan fractions and eliminating the supernatant containing the ammonium sulphate; repeating phase until elimination of ammonium sulphate still present in the mixture to give a precipitate of phase comprising the peptidoglycan fractions; resuspending the precipitate of phase in water and lyophilising, - in step the centrifugation of the suspension of step is performed at 900xg for 5 minutes; and - in step (III.bis) the centrifugation of the supernatant of step is performed at 10000xg for 15 minutes or at 6000xg for 20 minutes; and - in step the centrifugation of the mixture of step is performed at 10000xg for 15 minutes or at 6000xg for 20 minutes.