HYDROLYTIC BREAKDOWN OF LACTOFERRICIN BY LACTIC ACID BACTERIA

Authors: Paul, Moushumi; Somkuti, George

Submitted to: Journal of Industrial Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/2/2009
Publication Date: 1/6/2010
Citation: Paul, M., Somkuti, G.A. 2010. HYDROLYTIC BREAKDOWN OF LACTOFERRICIN BY LACTIC ACID BACTERIA. Journal of Industrial Microbiology and Biotechnology. 37: p. 173.

Interpretive Summary: The development of supplements that can be added to foods, especially yogurt, which contains active bacterial cultures, presents a constant challenge. Any extra ingredients added must survive the sometimes harsh processing stresses involved in the manufacture of these foods. Bacterial cultures that are used to make yogurt have enzymes (peptidases) associated with them that degrade proteins. The research addressed the possibility of using a milk-protein derived compound called lactoferricin in fermented dairy products by determining its survivability under yogurt-making conditions. Lactoferricin is a peptide with antimicrobial properties that make it potentially useful in protecting foods like yogurt from the effects of spoilage and pathogenic bacteria. The impact of the bacteria-associated peptidases on lactoferricin was monitored over a four hour period at pH 7.0. Degradation products were more closely analyzed to determine if sites of breakdown were predictable. Results showed that degradation of lactoferricin by these peptidases is random, but relative to other compounds with similar uses, lactoferricin is hardier and survives yogurt-making conditions better. This suggests that the use of lactoferricin as a natural food grade antimicrobial agent is feasible in yogurt-type foods.

Technical Abstract: Lactoferricin is a 25 amino acid antimicrobial peptide domain that is liberated by pepsin digestion of lactoferrin in bovine milk. Along with its antibacterial properties, lactoferricin has also been reported to have immunostimulatory, antiviral, and anticarcinogenic effects. There is substantial potential within the food industry for novel antimicrobials as protection agents against spoilage and pathogenic bacteria. Commercial uses of these types of compounds is severely limited, however, by their inability to survive food processing environments that include fluctuating temperature ranges or changes in local pH. To this end, the degradation of lactoferricin was monitored during its incubation with two types of lactic acid bacteria used in yogurt making, Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus, to assess if this milk-protein derived compound can survive yogurt-making processes. Analysis of the hydrolysis products isolated from these experiments indicates that lactic acid bacteria-associated peptidases extensively degrade this peptide. However, compared to similar peptides that undergo complete degradation under these conditions, the 25 amino acid lactoferricin is apparently more robust, with approximately half of the starting material remaining after four hours of incubation. The findings implied the potential of lactoferricin as a food grade antimicrobial agent in protecting yogurt-like foods against contamination by undesirable microbes.