Dear, Eman Ali,

Proteinase activity can be determined by utilisation of API ZYM system.

Please look this paper, most probably you will find information needed.

Sincerely,

Vitalijs

Dear EMAN ALI,

first you must test this activity if  exist by cultur touch with strain Lactobacillus in milk agar . if you have lyse of casein you can explore the activity.

best regards

Thanks all for reply, the strain already has proteolytic activity but I would like to use chromogenic sub (N-Succinyl-Ala-Ala-Pro-Phe p-nitroanilide) not casein as I use whey isolate not milk, but I can not detect the exact time for measuring if I use one measure assay with stopping agent , sample volume  I used1-5 ml which give small pellet and also  the correct sampling method with anaerobic incubation in anaerobic jar if I want to dtect the highest activity time

I tried the protocol on the attached article

Thanks