Acta Scientiarum Polonorum Technologia Alimentaria

Background. Ferulic acid esterases (FAE, EC 3.1.1.73), also known as feruloyl esterases, cinnamic acid esterases or cinnamoyl esterases, belong to a common group of hydrolases distributed in the plant kingdom. Especially the fungal enzymes were very well characterised in the past whereas the enzyme was rarely found in the lactic acid bacteria (LAB) strains. It is well known that strong antioxidants free phenolic acids can be released from the dietary fiber by the action of intestinal microflora composed among others also of Lactobacillus strains. The aim of this study was to examine four Lactobacillus strains (L. acidophilus K1, L. rhamnosus E/N, PEN, OXY)for the ability to produce extracellular FAE on different synthetic and natural carbon sources.

Material and methods. The LAB strains were grown in the minimal growth media using German wheat bran, rye bran, brewers’ spent grain, isolated larchwood arabinogalactan, apple pectin, corn pectin, methyl ferulate, methyl p-coumarate, methyl syringate or methyl vanillate as the sole carbon source. FAE activity was determined using the post-cultivation supernatants, methyl ferulate and HPLC with UV detection.

Results. The highest FAE activity was obtained with L. acidophilus K1 and methyl ferulate (max. 23.34 ±0.05 activity units) and methyl p-coumarate (max. 14.96 ±0.47 activity units) as carbon sources. L. rhamnosus E/N, OXY and PEN exhibited the limited ability to produce FAE with cinnamic acids methyl esters. Methyl syringate and methyl vanillate
(MS and MV) were insufficient carbon sources for FAE production. Brewers’ spent grain was the most suitable substrate for FAE production by L. acidophilus K1 (max. 2.64 ±0.06 activity units) and L. rhamnosus E/N, OXY and PEN. FAE was also successfully induced by natural substrates rye bran, corn pectin (L. acidophilus K1), German wheat bran and larchwood arabinogalactan (E/N, PEN) or German wheat bran and corn pectin (OXY).

Conclusions. This study proved the ability of Lactobacillus strains to produce FAE in the presence of a wide range of different ester-bound substrates. The highest enzyme activities obtained in the presence of synthetic phenolic acids methyl esters suggest that the bacteria were forced to produce FAE whereas in the presence of natural substrates other carbon sources were exploited. FAE is the enzyme of the minor importance during the decomposition of the food matrix during the intestinal absorption but the further characterisation of these enzymes should be carried on.