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- Evaluation of a bacteriocinogenic Lactobacillus plantarum strain on the microbiological characteristics of “Alheira de Vitela”Publication . Macieira, Ariana; Albano, Helena; Pinto, Miguel; Linheiro, Raquel; Barbosa, Joana; Teixeira, PaulaLactic Acid Bacteria (LAB) and their bacteriocins can be successfully used as natural preservatives in meat products. This work aimed to investigate the effect of fresh and lyophilized starter cultures of an autochthonous bacteriocinogenic LAB strain (Lactobacillus plantarum ST153Ch: bac + culture) on the microbiological characteristics of “Alheira”, a traditional Portuguese smoked product. “Alheira” with the addition of fresh or lyophilized culture (ca. 108 cfu/g) and “Alheira” control (no bacteriocinogenic culture added) were produced by an industrial meat company. The antilisterial activity of this culture in this food matrix was investigated, with some samples being inoculated with Listeria monocytogenes (ca. 105 cfu/g). Detection of L. monocytogenes, Salmonella spp., sulphite reducing clostridia, Yersinia enterocolitica and enumeration of L. monocytogenes, Staphylococcus aureus, Bacillus cereus, Escherichia coli, Enterobacteriaceae, lactic acid bacteria, yeasts and moulds were performed immediately after production and at 3, 7, 15, 21, 28, 60 and 90 days of storage at 4 ℃, according to ISO methodologies. Also, a 16S rRNA Gene Analysis was performed of the microbial communities of “Alheira” with and without the lyophilized bacteriocinogenic culture. Pathogenic and indicator organisms were not detected or were below acceptable levels in all samples. LAB counts increased during storage and reached similar values after 15 days (ca. 1010 cfu/g) in all samples. There was a clear trend for a higher reduction of L. monocytogenes in the presence of the bioprotective culture, more pronounced during the initial 15 days of storage. From the analysis of the microbial communities of samples of “Alheiras” at different stages of fermentation, Leuconostocaceae and Lactobacillaceae predominated in all the samples and Lactobacillus was the genus more prevalent in “Alheiras” after 60 days of storage with the addition of bacteriocinogenic culture.
- Production of an antilisterial medium to be used in the industry of portuguese tradicional meat productsPublication . Macieira, Ariana; Barbosa, Joana; Albano, Helena; Teixeira, Paula
- Characterization of a lactiplantibacillus plantarum r23 isolated from arugula by whole-genome sequencing and its bacteriocin production abilityPublication . Barbosa, Joana; Albano, Helena; Silva, Beatriz; Almeida, Maria Helena; Nogueira, Teresa; Teixeira, PaulaLactiplantibacillus plantarum is one of the lactic acid bacteria species most used as probiotics and starter cultures in food production. Bacteriocin-producers Lpb. plantarum are also promising natural food preservatives. This study aimed to characterize Lpb. plantarum R23 and its bacteriocins (R23 bacteriocins). The genome sequence of Lpb. plantarum R23 was obtained by whole-genome sequencing (WGS) in an Illumina NovaSeq platform. The activity of Lpb. plantarum R23-produced bacteriocin against two Listeria monocytogenes strains (L7946 and L7947) was evaluated, and its molecular size was determined by tricine-SDS-PAGE. No virulence or antibiotic resistance genes were detected. Four 100% identical proteins to the class II bacteriocins (Plantaricin E, Plantaricin F, Pedi-ocin PA-1 (Pediocin AcH), and Coagulin A) were found by WGS analysis. The small (<6.5 kDa) R23 bacteriocins were stable at different pH values (ranging from 2 to 8), temperatures (between 4 and 100 °C), detergents (all, except Triton X-100 and Triton X-114 at 0.01 g/mL), and enzymes (catalase and α-amylase), did not adsorb to the producer cells, had a bacteriostatic mode of action and their maximum activity (AU/mL = 12,800) against two L. monocytogenes strains occurred between 15 and 21 h of Lpb. plantarum R23 growth. Lactiplantibacillus plantarum R23 showed to be a promising bio-preservative culture because, besides being safe, it produces a stable bacteriocin or bacteriocins (har-bors genes encoding for the production of four) inhibiting pathogens as L. monocytogenes. Further studies in different food matrices are required to confirm this hypothesis and its suitability as a future starter culture.
- Evaluation of a bacteriocin-producing strain of pediococcus acidilactici as a biopreservative for "alheira", a fermented meat sausagePublication . Albano, Helena; Pinho, Catarina; Leite, Daniela; Barbosa, Joana; Silva, Joana; Carneiro, Luísa; Magalhães, Rui; Hogg, Tim; Teixeira, PaulaThis study was conducted to evaluate the ability of Pediococcus acidilactici HA-6111-2, a PA-1 bacteriocinproducing lactic acid bacterium (LAB), isolated from ‘‘Alheira” to inhibit a cocktail of Listeria innocua strains during production and shelf-life of these products. The bacteriocinogenic culture reduced the Listeria population below the detection limit (1.5log CFU/g) and had no effect on the growth of the natural LAB flora or on the pH. Pathogenic organisms were not detected in any sample. The presence of some virulence factors and antibiotic resistances of the strain to be used as a bioprotective culture were investigated. P. acidilactici HA-6111-2 did not produce any of the biogenic amines tested; no formation of biofilms was observed; more L(+)lactic acid was produced than its isomer D(-); no gelatinase, DNase or lipase activity was recorded; no structural genes for the haemolysin, enterococcal surface protein, hydrolytic compounds, aggregation protein and cell-wall adhesins were detected, no significant antibiotic resistances were found. P. acidilactici HA-6111-2 appears to have potential as a bioprotective culture during ‘‘Alheira” fermentation. Moreover, a trained panel considered the protected product to be sensorially acceptable.
- Screening of bacteriocinogenic lactic acid bacteria cultures and their characterization as potential probioticsPublication . Pinto, Ana; Barbosa, Joana; Albano, Helena; Teixeira, Paula
- Inhibitory effect of lactobacillus plantarum FL75 and Leuconostoc mesenteroides FL14 against foodborne pathogens in artificially contaminated fermented tomato juicesPublication . Bah, Aissé; Albano, Helena; Barbosa, Joana; Fhoula, Imene; Gharbi, Yosra; Najjari, Afef; Boudabous, Abdellatif; Teixeira, Paula; Ouzari, HaddaTomatoes and tomato based-foods contain beneficial microorganisms and various organic acids that have important nutritional values for human. The objective of this study was to access the physiochemical properties of fermented tomatoes juices and to evaluate the competitiveness of lactic acid bacteria (LAB) against Listeria monocytogenes, Listeria innocua, and Salmonella spp., in artificially contaminated tomato juice. Microbial counting (LAB, fungi Salmonella spp., and Listeria spp.) was performed after fermentation and weekly during storage. Different organic acids (Lactic, succinic, and acetic) and ethanol were also monitored using HPLC method. Color parameters were also determined. The results showed an increase of lactic and acetic acid content, during fermentation and storage of juices inoculated with Lactobacillus plantarum and Leuconostoc mesenteroides at 25 degrees C. Besides, citric acid and ethanol revealed higher content at the end of storage compared to that registered at 4 degrees C. The pH from tomatoes juices decreased from an initial value of 4.5 to below 3.2. Alongside, foodborne pathogen population was significantly suppressed in tomatoes juices when the samples were coinoculated with LAB strains. Moreover, the inhibition of Salmonella species was faster compared to that of Listeria. After four weeks of storage at 4 degrees C, Lb. plantarum and Lc. mesenteroides showed high survival rate, while pathogenic bacteria, yeasts, and molds cell numbers decreased drastically in all the contaminated vials. This work highlights the efficiency of Lb. plantarum and Lc. mesenteroides as potential starters for developing nutritious and safe fermented tomato juice products.
- Antimicrobial potential of different propolis extractsPublication . Oliveira, Mónica; Teixeira, Helena; Barbosa, Joana; Albano, Helena; Teixeira, Paula
- Chemical and microbiological characterization of Portuguese “innovative” alheirasPublication . Moreira, Inês Azevedo; Barbosa, Joana; Albano, Helena; Teixeira, Paula
- Screening of bacteriocinogenic lactic acid bacteria and their characterization as potential probioticsPublication . Pinto, Ana; Barbosa, Joana; Albano, Helena; Isidro, Joana; Teixeira, PaulaProbiotics are living microorganisms used as nutritional additives that confer health benefits on the host. Their use in food products is very attractive, especially if they could also inhibit important foodborne athogens. In this study, antimicrobial activity against several foodborne pathogens was screened for 280 lactic acid bacteria (LAB) isolated from di erent food products and the probiotic characteristics of bacteriocinogenic isolates were evaluated. Seven out of 280 LAB isolates were selected due to their bacteriocinogenic properties and identified by 16S rRNA gene sequence analysis as Pediococcus pentosaceus (n = 6) and Lactobacillus plantarum (n = 1). Virulence factors and antibiotic resistances were not detected for any of the isolates. Except for L. plantarum R23, all the isolates were able to survive through the simulated gastrointestinal tract conditions. Only P. pentosaceus CFF4 was able to adhere to Caco-2 cells after the simulated gastrointestinal tract passage. In conclusion, even though in vivo studies should be performed, P. pentosaceus CFF4, which was also able to inhibit the growth of foodborne pathogens in vitro, seems to be a potential probiotic to be used in the food industry.
- Microbiological characterization of different formulations of alheiras (fermented sausages)Publication . Silva, Julieta; Barbosa, Joana; Albano, Helena; Sequeira, Maria; Pinto, Ana; Bonito, Conceição Costa; Saraiva, Margarida; Teixeira, PaulaDifferent ingredients in old recipes are becoming popular and the traditional alheira did not escape to this new trend. The objective of this preliminary study was to characterize microbiologically nine different formulations of alheira from five producers. In this sense, isolates obtained were characterized through different phenotypic and biochemical tests. Their susceptibility to different antimicrobials and the presence of virulence factors was also investigated. Lactic acid bacteria were the predominant microbiota, but pathogenic bacteria as coagulase-positive staphylococci, Listeria monocytogenes and Salmonella spp. as well as indicator organisms were also found. Several virulence factors were produced among the different groups of isolates, with a high incidence of isolates producing β-haemolysis. Along with their potential pathogenic activity, also several antimicrobial resistances were found being the majority of isolates classified as multi-resistant. At our knowledge, this is the first study with these new formulations of alheira. A higher number of products must be analyzed, but we believe that results obtained in this study should help to alert consumers for the need of safe cooking time/temperatures of these products.