Atividade antimicrobiana de bactérias lácticas de embutidos curados frente a Listeria monocytogenes

Postbiotics: Current Trends in Food and Pharmaceutical Industry

Postbiotics are non-viable bacterial products or metabolic byproducts produced by probiotic microorganisms that have biologic activity in the host. Postbiotics are functional bioactive compounds, generated in a matrix during anaerobic fermentation of organic nutrients like prebiotics, for the generation of energy in the form of adenosine triphosphate. The byproducts of this metabolic sequence are called postbiotics, these are low molecular weight soluble compounds either secreted by live microflora or released after microbial cell lysis. A few examples of widely studied postbiotics are short-chain fatty acids, microbial cell fragments, extracellular polysaccharides, cell lysates, teichoic acid, vitamins, etc. Presently, prebiotics and probiotics are the products on the market; however, postbiotics are also gaining a great deal of attention. The numerous health advantages of postbiotic components may soon lead to an increase in consumer demand for postbiotic supplements. The most recent research aspects of postbiotics in the food and pharmaceutical industries are included in this review. The review encompasses a brief introduction, classification, production technologies, characterization, biological activities, and potential applications of postbiotics.

Probiotic and Antifungal Attributes of Lactic Acid Bacteria Isolates from Naturally Fermented Brazilian Table Olives

Research with fermented olives as a source of wild Lactic Acid Bacteria (LAB) strains with probiotic and biotechnological characteristics constitutes a promising field of work. The present study evaluated in vitro probiotic, antifungal, and antimycotoxigenic potential of LAB isolates from naturally fermented Brazilian table olives. Among fourteen LAB isolates, the Levilactobacillus brevis CCMA 1762, Lactiplantibacillus pentosus CCMA 1768, and Lacticaseibacillus paracasei subsp. paracasei CCMA 1770 showed potential probiotic and antifungal properties. The isolates showed resistance to pH 2.0 (survival ≥ 84.55), bile salts (survival ≥ 99.44), and gastrointestinal tract conditions (survival ≥ 57.84%); hydrophobic cell surface (≥27%); auto-aggregation (≥81.38%); coaggregation with Escherichia coli INCQS 00181 (≥33.97%) and Salmonella Enteritidis ATCC 564 (≥53.84%); adhesion to the epithelial cell line Caco-2 (≥5.04%); antimicrobial activity against the bacteria S. Enteritidis ATCC 564 (≥6 mm), Listeria monocytogenes ATCC 19117 (≥6 mm), Staphylococcus aureus ATCC 8702 (≥3 mm), and the fungi Penicillium nordicum MUM 08.16 (inhibition ≥ 64.8%). In addition, the strains showed the ability to adsorb the mycotoxins aflatoxin B1 (≥40%) and ochratoxin A (≥34%). These results indicate that LAB strains from naturally fermented Brazilian table olives are potentially probiotic and antifungal candidates that can be used for food biopreservation.

Listeria monocytogenes biofilm inhibition on food contact surfaces by application of postbiotics from Lactobacillus curvatus B.67 and Lactobacillus plantarum M.2

Owing to their preservative and antimicrobial effects, postbiotics (metabolic byproducts of probiotics) are promising natural components for the food industry. Therefore, the present study aimed to investigate the efficacy of postbiotics collected from isolated Lactobacillus curvatus B.67 and Lactobacillus plantarum M.2 against Listeria monocytogenes pathogens in planktonic cells, motility, and biofilm states. The analysis of the metabolite composition of the postbiotics revealed various organic acids, along with a few well-known bacteriocin-encoding genes with potential antimicrobial effects. Postbiotics maintained their residual antimicrobial activity over the pH range 1-6 but lost all activity at neutral pH (pH 7). Full antimicrobial activity (100%) was observed during heat treatment, even under the autoclaving condition.Minimum inhibitory concentration (MICs) of L. curvatus B.67 and L. plantarum M.2 against L. monocytogenes were 80 and 70 mg/mL, respectively. However, four sub-MICs of the postbiotics (1/2, 1/4, 1/8, and 1/16 MIC) were tested for inhibition efficacy against L. monocytogenes during different experiment in this study. Swimming motility, biofilm formation, and expression levels of target genes related to biofilm formation, virulence, and quorum-sensing were significantly inhibited with increasing postbiotics concentration. Postbiotics from L. plantarum M.2 exhibited a higher inhibitory effect than the postbiotics from L. curvatus B.67. Nonetheless, both these postbiotics from Lactobacillus spp. could be used as effective bio-interventions for controlling L. monocytogenes biofilm in the food industry.

Probiotic properties of yeasts isolated from Brazilian fermented table olives

AIMS

To investigate the probiotic potential of yeasts isolated from naturally fermented Brazilian table olives.

METHODS AND RESULTS

Eighteen yeast strains were tested in terms of: safety; survival of gastrointestinal and digestion conditions; antimicrobial activity; cellular hydrophobicity; autoaggregation ability and adhesion to epithelial cells; coaggregation and inhibition of pathogenic bacteria adhesion. Six yeasts showed favourable results for all probiotic attributes: Saccharomyces cerevisiae CCMA 1746, Pichia guilliermondii CCMA 1753, Candida orthopsilosis CCMA 1748, Candida tropicalis CCMA 1751, Meyerozyma caribbica CCMA 1758 and Debaryomyces hansenii CCMA 1761. These yeasts demonstrated resistance to 37°C, pH 2·0 and bile salts, and survived in vitro digestion (≥10⁶  CFU per ml). Furthermore, the yeasts exhibited a hydrophobic cell surface (42·5-92·2%), autoaggregation capacity (41·0-91·0%) and adhesion to Caco-2 (62·0-82·8%) and HT-29 (57·6-87·3%) epithelial cell lines. Also, the strains showed antimicrobial activity against Salmonella Enteritidis as well as the ability to coaggregate and reduce the adhesion of this pathogen to intestinal cells.

CONCLUSIONS

Autochthonous yeasts from naturally fermented Brazilian table olives have probiotic properties, with potential for development of new probiotic food products.

SIGNIFICANCE AND IMPACT OF STUDY

These data are important and contribute to the knowledge of new potential probiotic yeasts capable of surviving gastrointestinal tract conditions and inhibiting pathogenic bacteria.

A review on preparation and chemical analysis of postbiotics from lactic acid bacteria

Postbiotics may be defined as soluble metabolites released by food-grade microorganisms during the growth and fermentation in complex microbiological culture, food or gut. It is rich in high and low molecular weight biologically active metabolites. There are still gaps concerning these substances, mainly how to use them for food applications. Although the most recent work on preparation and application of postbiotics from several probiotics are very encouraging, the suitability of postbiotics to combat microorganisms that deal with food safety should be tested mainly by analyzing the chemical composition and conducting antagonistic tests. Consequently, foods can effectively benefit from an identified postbiotic with a defined effect. This review approached the recent advances in relation to the preparation of postbiotics from lactic acid bacteria. The function of different instrumental analysis techniques and factors affecting the chemical composition of postbiotics were also comprehensively reviewed.

Characterization and Antibacterial Potential of Lactic Acid Bacterium Pediococcus pentosaceus 4I1 Isolated from Freshwater Fish Zacco koreanus

This study was undertaken to characterize a lactic acid bacterium 4I1, isolated from the freshwater fish, Zacco koreanus. Morphological, biochemical, and molecular characterization of 4I1 revealed it to be Pediococcus pentosaceus 4I1. The cell free supernatant (CFS) of P. pentosaceus 4I1 exhibited significant (p < 0.05) antibacterial effects (inhibition zone diameters: 16.5-20.4 mm) against tested foodborne pathogenic bacteria with MIC and MBC values of 250-500 and 500-1,000 μg/mL, respectively. Further, antibacterial action of CFS of P. pentosaceus 4I1 against two selected bacteria Staphylococcus aureus KCTC-1621 and Escherichia coli O157:H7 was determined in subsequent assays. The CFS of P. pentosaceus 4I1 revealed its antibacterial action against S. aureus KCTC-1621 and E. coli O157:H7 on membrane integrity as confirmed by a reduction in cell viability, increased potassium ion release (900 and 800 mmol/L), reduced absorption at 260-nm (3.99 and 3.77 OD), and increased relative electrical conductivity (9.9 and 9.7%), respectively. Gas chromatography-mass spectrometry (GC-MS) analysis of the CFS of P. pentosaceus 4I1 resulted in the identification of seven major compounds, which included amino acids, fatty acids and organic acids. Scanning electron microscopic-based morphological analysis further confirmed the antibacterial effect of CFS of P. pentosaceus 4I1 against S. aureus KCTC-1621 and E. coli O157:H7. In addition, the CFS of P. Pentosaceus 4I1 displayed potent inhibitory effects on biofilms formation by S. aureus KCTC-1621 and E. coli O157:H7. The study indicates the CFS of P. pentosaceus 4I1 offers an alternative means of controlling foodborne pathogens.

Atividade antimicrobiana de bactérias lácticas isoladas de queijo-de-minas artesanal do Serro (MG) frente a microrganismos indicadores

Isolaram-se 192 cepas de bactérias lácticas de cinco amostras de queijo-de-minas artesanal, oriundos da região do Serro, MG. Os resultados da prova de inibição direta indicaram que 48 cepas isoladas (25%) foram capazes de inibir o crescimento in vitro de microrganismos indicadores, dentre os quais Staphylococcus aureus e Listeria monocytogenes. As 48 cepas foram submetidas à prova de inibição indireta. Verificou-se que 20,8% (10/48) das cepas demonstraram amplo espectro antimicrobiano frente a microrganismos como: Salmonella enteritidis var. typhimurium, Staphylococcus aureus, Listeria monocytogenes e Listeria innocua. Nenhuma das cepas isoladas foi capaz de inibir Escherichia coli.

Atividade antimicrobiana de bactérias lácticas isoladas de produtos cárneos frente a Listeria monocytogenes e Staphylococcus aureus

De seis amostras de pernil desossado curado e três amostras de salame tipo italiano artesanal foram isoladas 288 cepas de bactérias lácticas. Pelo teste de inibição direta 59 delas foram capazes de inibir in vitro o desenvolvimento de cepas de Listeria monocytogenes e de Staphylococcus aureus, o que demonstra que produzem compostos inibitórios.