Kim B. Heo B.
CKDBiO, South Korea

Scientific evidence is steadily accumulating on beneficial impact of lactic acid bacteria (LAB) on host health, including metabolic syndrome, immune disorders and inflammatory bowel disease. Providing LAB to customers with their full potency requires exquisitely standardized process and comprehensive understanding on microbial characteristics. Assurance of microbial activity and stability can be considered as one of the most important criteria, according to the definition of the FAO/WHO referring to “live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host”.
Commonly industrial LAB production process includes following steps such as concentration of LAB culture, addition of buffers such as cryoprotectants and coating materials, freeze-drying, pulverizing, and packaging. In these steps, LAB are exposed to various physical and chemical stresses. Not only production process but also survival rate of LAB can be severely reduced by oxygen and low pH or high concentration of bile salts during preservation process or after intake of the products. Probiotics producers provide different ways to reduce these environmental stresses on LAB such as building multiple layers of physical barriers on outermost area of LAB cell membrane which so called double, triple, quadruple coatings etc. However, at the same time, increasing layers of coating lowers economic efficiency and causes a problem on adequate layer degradation in the intestine.

In this study, we performed various experiments to monitor stress responses and stability of LAB during followed downstream processes as well as the LAB culture process. For this purpose, an amino acid such as proline was added during or after the bacterial culturing process and then amino acid concentration and osmotic pressure of LAB culture broth was analyzed. Also, we evaluated the survival rate of LAB during downstream processes as well as the stability of freeze-dried LAB.

As a results, we observed a correlation between the osmotic pressure and proline concentration of LAB culture environments. Also, when an amino acid such as proline were added to medium during or after the culturing process, it was shown that the supplemented amino acid could significantly increase not only the survival rate of LAB during freeze-drying but also anti-oxidant activity, storage stability and resistance to acid and bile salt of freeze-dried LAB.

It is considered that the increasing stability by addition of an amino acid especially proline is associated with high osmotic pressure adaptation and/or the protective effect of amino acid. Therefore, it seems that our improved technology is economic and advanced tool for a high productivity of LAB.

Keywords: Lactic acid bacteria (LAB), Amino acid, Probiotics, Proline, Freeze-drying, Storage stabil

Kim B. & Heo B. (2016). Effect of amino acid feeding on lactic acid bacteria stability. Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 102.). IPC2016

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