Antimicrobial and antioxidant activities of Enterococcus species isolated from meat and dairy products

Abstract

Lactic acid bacteria (LAB) have an important role in a great variety of fermented foods. In addition to their contribution to sensory characteristics, they enhance food preservation and can be used as probiotics. In this study, the antimicrobial and antioxidant activities of culture supernatants and cell free extracts of 16 LAB isolated from meat and dairy products were investigated. The bacterial were identified by 16S rRNA sequencing. GenBank BLAST analysis revealed that all the isolates belong to Enterococcus faecium species. Antimicrobial activity against the indicator microorganism (Listeria monocytogenes) was observed at 11 culture supernatants and 4 cell free extracts. The sensibility of culture supernatant was evaluated by proteinase K and trypsin and it was observed that activity of antimicrobial substance was completely lost after the treatment. All of the isolates showed antioxidant activity as determined by the Thiobarbituric Acid Reactive Substances (TBARS) method with both types of extracts. When the antioxidant capacity was investigated using ABTS •+ method (2,2 azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) and DPPH method (2,2-diphenyl-1-picrylhydrazyl) it was observed that only culture supernatants showed antioxidant capacity. These bacteria could particularly help to reduce or inhibit pathogenic microorganisms as well as oxidative spoilage in foods and feed.Keywords: antimicrobial activity, antioxidant, Enterococcus, lactic acid bacteria, molecular characterization.Atividade antimicrobiana e antioxidante de espécies de Enterococcus isoladas de carne e produtos lácteos ResumoAs bactérias ácido láticas (BAL) têm um papel importante em uma grande variedade de alimentos fermentados. Em adição à sua contribuição para as características sensoriais, estes microorganismos melhoram a conservação de alimentos e podem ser utilizados como probióticos. Neste estudo, as atividades antimicrobiana e antioxidante do sobrenadante e dos extratos livres de células de 16 isolados de LAB de carne e produtos lácteos foram investigadas. Os isolados foram identificados pelo sequenciamento da região 16S do rRNA. Após a comparação das sequências obtidas com aquelas disponíveis na base de dados GenBank, observou-e que todos os isolados foram pertencentes à espécie Enterococcus faecium. A atividade antimicrobiana contra o microrganismo indicador (Listeria monocytogenes) foi observada no sobrenadante das culturas em 11 isolados, e nos extratos livres de células por 4 isolados. A sensibilidade da cultura sobrenadante foi avaliada pela proteinase K e tripsina e observou-se que a atividade da substância antimicrobiana foi completamente perdida após o tratamento com as enzimas proteolíticas. Todos os isolados apresentaram atividade antioxidante, como determinado pelo método do ácido tiobarbitúrico de substâncias reativas (TBARS) com ambos os tipos de extratos. Quando a capacidade antioxidante foi investigada usando o método do ABTS (2,2 azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) e o método de DPPH (2,2-di...

Characterization of technological and probiotic properties of indigenous Lactobacillus spp. from south Brazil

“…a Proteolytic activity, diacetyl production, titratable acidity (% acid) and pH variation (Δ pH); b antioxidant activity of the supernatant (AAS), antioxidant activity of the intracellular extract (AAIE), resistance to intestinal juice with (RIJ+) and with no addition of bile salts (RIJ-), resistance to gastric juice (RGJ) at two pH values (2.5 and 3.0), proteolytic activity and diacetyl production; and c Intensity of the resistance to 12 antibiotics -0.8 -0.4 0.4 1. (Pieniz et al 2015). The antioxidant potential observed in the lactobacilli studied in this work suggests that they may be useful for the development of functional foods acting as antioxidants to eliminate free radicals from host cells.…”

Frequency of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) in non-clinical Enterococcus faecalis and Enterococcus faecium strains

“…Enterococci are important Gram-positive bacteria recognized as part of gut microbiota in humans and animals, and they are widely distributed in soil, water, plants and foods (Cassenego et al, 2013;Lebreton et al, 2014;Pieniz et al, 2015;Santestevan et al, 2015;Prichula et al, 2016;Medeiros et al, 2017). Their ubiquity reflects its ability to survive in a variety of environmental stressors (Byappanahalli et al, 2012).…”

Antioxidant Activities of Lactic Acid Bacteria for Quality Improvement of Fermented Sausage

“…However, reactive oxygen species such as hydroxyl radicals (•OH), superoxide anions (•O 2 − ), and hydrogen peroxide are produced during the process (Choi and others ). An oxidative stress process can damage biomolecules, including proteins, lipids, and nucleic acids, when reactive oxygen species are generated as a result of excess or deficient cellular defenses (Pieniz and others ). This damage may result in a variety of degenerative diseases such as cancer, atherosclerosis, and cirrhosis (Pieniz and others ).…”

“…An oxidative stress process can damage biomolecules, including proteins, lipids, and nucleic acids, when reactive oxygen species are generated as a result of excess or deficient cellular defenses (Pieniz and others ). This damage may result in a variety of degenerative diseases such as cancer, atherosclerosis, and cirrhosis (Pieniz and others ). Studies have shown that LAB isolates have the scavenging capacities of free radicals such as 1,1‐diphenyl‐2‐picrylhydrazyl free radical (DPPH•), OH•, and O 2 − • (Chen and others ; Ji and others ).…”