CERELA   05438
CENTRO DE REFERENCIA PARA LACTOBACILOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
ESTERASES OF LACTIC ACID BACTERIA: THEIR CONTRIBUTION TO THE DEVELOPMENT OF FUNCTIONAL FOODS
Autor/es:
ABEIJON MUKDSI, MARIA CLAUDIA; MEDINA, ROXANA BEATRIZ; PEREZ CHAIA, ADRIANA
Lugar:
San Miguel de Tucumán
Reunión:
Mesa redonda; V Simposio Internacional de Bacterias Lácticas; 2016
Institución organizadora:
Centro de Referencia para Lactobacilos (CERELA)-CONICET
Resumen:
Esterases (carboxyl ester hydrolases) constitute a diverse group of enzymes that catalyze the cleavage and formation of ester bonds. They have a wide range of applications in agricultural, food and pharmaceutical industries. Esterases of lactic acid bacteria (LAB) play a major role in fermented foods, contributing to flavor development and antioxidant compound release. These enzymes are responsible for the hydrolysis of milk fat glycerides releasing short-chain fatty acids (SCFA). Moreover, in presence of alcohol (mainly ethanol), esterases can catalyze the synthesis of SCFA esters via two main reaction mechanisms: esterification and alcoholysis. SCFA and ethyl esters of SCFA are important flavor compounds in many cheese types, imparting piquant and fruity-flavor notes, respectively. In our laboratory, several LAB strains isolated from small ruminants? milk and artisanal cheeses produced in Northwest Argentina were selected for their esterase activity. They presented multiple esterases, intracellular and cell-surface associated, displaying different substrate specificity. These strains were used as adjunct cultures in miniature ewe/goat milk cheeses, where they contributed to the release of SCFA (2 to 6 carbon atoms) and the formation of the corresponding ethyl esters during ripening. In recent years, there has been a growing interest for the potential beneficial effects of esterases in human and animal health. In this context, feruloyl esterases (FE) have gained particular attention. FE are a subclass of carboxyl ester hydrolases that catalyze the release of antioxidant hydroxycinnamic acids, mainly ferulic acid (FA), from their non-digestible ester-linked forms naturally present in vegetable foods. Hydroxycinnamate esters arrive unaltered to the colon, where they are hydrolyzed by FE from intestinal microbiota and mucosa. Free FA can then be absorbed and provide substantial protection against oxidative stress-related ailments such as cancer, diabetes, cardiovascular and neurodegenerative diseases, and in ageing. FE-producing LAB can be used to supply exogenous FE activity into the gut to enhance FA release from dietary fiber in vivo, thus improving the host oxidative status. In this regard, mice fed with a conventional balanced diet and administered with Lactobacillus fermentum CRL1446 (strain with high FE activity in vitro) via drinking water or goat milk cheese, showed an increase in intestinal FE activity and an improvement in oxidative status, evidenced by lower plasmatic thiobarbituric acid-reactive substance level and higher glutathione reductase activity, compared to non-treated mice. CRL1446 strain administration via drinking water also enhanced metabolic parameters (lower plasmatic glucose and total cholesterol levels) and exerted a bifidogenic effect. Similar results were observed in mice receiving a calorie restricted-diet and L. fermentum CRL1446. The effect of bile, probiotic intestinal adhesion and milk fat on bacterial/mucosal FE activity will also be discussed in this conference. In summary, these findings demonstrate that esterases of LAB can contribute to the development of novel functional foods directed to oxidative stress-related ailments with good flavor attributes.