Background. Ferulic acid esterases (or feruloyl esterases), a common group of hydrolases are very well distributed in the plant kongdom. The fungal feruloyl esterases were very extensively studied whereas probiotic lactic acid bacteria as the source of this enzyme were generally omitted. Free phenolic acids – strong antioxidants can be released from the dietary fiber by the action of intestinal lactic acid bacteria. The aim of this study was to examine the three probiotic Bifidobacterium strains to produce extracellular FAE on different synthetic and natural carbon sources.
Material and methods. Studies were carried out using Bifidibacteriumstrains (B. animalis Bi30, B. catenulatum KD 14 and B. longum KN 29). The strains were cultivated using minimal growth media containing selected natural and synthetic carbon sources: German wheat bran, rye bran, barley spent grain, isolated larchwood arabinogalactan, apple pectin, corn pectin, methyl esters of phenolic acids. The production of extracellular feruloyl esterase was estimated using the post cultivation supernatants and methyl ferulate. The concentration of ferulic acid released from the ester was determined using HPLC with DAD detection.
Results. The most efficient bacterial strain for FAE production was B. animalis cultivated in the presence of methyl p-coumarate and methyl ferulate as the main carbon sources (14.95 nmol·ml-1·min-1 and 4.38 nmol·ml-1·min-1, respectively). In the case of each FAE, the highest activity was obtained at 37oC (pH 6.3) in Theorell/Steinhagen buffer (B. animalis Bi30) or in Tris/HCl buffer (B. catenulatum KD14 and B. longum KN29). Taking under consideration all results, it should be noticed that the highest feruloyl esterase activities were obtained using synthetic methyl esters of phenolic acids.
Conclusions. The presented resultsbroaden the knowledgeabout the production of the feruloyl esterase by probiotic bacteria. Although the enzyme is only accessory during the hydrolysis of food components during intestinal digestion, some conclusions on the role of lactic acid bacteria in the release of food antioxidants phenolic acids can be established.