Navegando por Autor "Franco, Bernadette Dora Gombossy de Melo"

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Genetic diversity and some aspects of antimicrobial activity of lactic acid bacteria isolated from goat milk
(Applied Biochemistry and Biotechnology, 2015-01-31) Cavicchioli, Valéria Quintana; Dornellas, Wesley dos Santos; Perin, Luana Martins; Pieri, Fábio Alessandro; Franco, Bernadette Dora Gombossy de Melo; Todorov, Svetoslav Dimitrov; Nero, Luís Augusto
Lactic acid bacteria (LAB, n = 57) were previously obtained from raw goat milk, identified as Lactococcus spp. (n = 24) and Enterococcus spp. (n = 33), and characterized as bacteriocinogenic. Fingerprinting by pulsed field gel electrophoresis (PFGE) demonstrated high genetic diversity, and 30 strains were selected and exhibited strong antimicrobial activity against 46 target strains (LAB, spoilage, and foodborne pathogens). Six strains (Lactococcus lactis: GLc03 and GLc05; and Enterococcus durans: GEn09, GEn12, GEn14, and GEn17) were selected to characterize their bacteriocinogenic features, using Listeria monocytogenes ATCC 7644 as the target. The six strains produced bacteriocins at higher titer when incubated in MRS at 37 °C up to 12 h, when compared to growth at 25 and 30 °C. The produced bacteriocins kept their antimicrobial activity after exposure to 100 °C for 2 h and 121 °C for 20 min; the antimicrobial activity was also observed after treatment at pH 2.0 to 10.0, except for GLc03. L. monocytogenes populations were reduced approximately two logs after treatment with cell-free supernatants from the selected strains. These data show that goat milk can contain a diverse microbiota able to inhibit L. monocytogenes, a common pathogen found in dairy products, and can be potentially employed in biopreservation of food produced under different processing conditions.
Interference of raw milk autochthonous microbiota on the performance of conventional methodologies for Listeria monocytogenes and Salmonella spp. detection
(Microbiological Research, 2009-09-29) Nero, Luís Augusto; Mattos, Marcos Rodriguesde; Barros, Márcia de Aguiar Ferreira; Beloti, Vanerli; Franco, Bernadette Dora Gombossy de Melo
Pathogen detection in foods by reliable methodologies is very important to guarantee microbiological safety. However, peculiar characteristics of certain foods, such as autochthonous microbiota, can directly influence pathogen development and detection. With the objective of verifying the performance of the official analytical methodologies for the isolation of Listeria monocytogenes and Salmonella in milk, different concentrations of these pathogens were inoculated in raw milk treatments with different levels of mesophilic aerobes, and then submitted to the traditional isolation procedures for the inoculated pathogens. Listeria monocytogenes was inoculated at the range of 0.2–5.2 log CFU/mL in treatments with 1.8–8.2 log CFU/mL. Salmonella Enteritidis was inoculated at 0.9–3.9 log CFU/mL in treatments with 3.0–8.2 log CFU/mL. The results indicated that recovery was not possible or was more difficult in the treatments with high counts of mesophilic aerobes and low levels of the pathogens, indicating interference of raw milk autochthonous microbiota.
Microbiological testing for the proper assessment of the hygiene status of beef carcasses
(Microorganisms, 2019) Camargo, Anderson Carlos; Cossi, Marcus Vinícius Coutinho; Silva, Wladimir Padilha da; Bersot, Luciano dos Santos; Landgraf, Mariza; Baranyi, József; Franco, Bernadette Dora Gombossy de Melo; Augusto, Nero Luís
Microbiological testing is an important quality management tool in the food industry. In this study, the hygiene status of beef carcasses sampled in eight Brazilian slaughterhouses was assessed by enumeration of different hygiene indicator microorganisms, and a model to establish potential associations among these counts was proposed. The carcasses (n = 464) were surface sampled at four slaughtering steps (step 1: Hide after bleeding; step 2: Carcass after hide removal; step 3: Carcass after evisceration; step 4: Carcass after end washing) and subjected to a counting of mesophilic aerobes (MA), Enterobacteriaceae (EB), total coliforms (TC), and Escherichia coli (EC) using PetrifilmTM plates. Among the sampled beef carcasses (step 4), 32 (6.9%) and 71 (15.3%) presented counts above the microbiological criteria established by (EC) No. 1441/2007 for MA and EB, respectively. Thus, indicating that improvements in slaughter hygiene and a review of process controls are demanded in some of the studied slaughterhouses. The log count differences of EC, TC, and EB from MA were considered as response variables as a function of the slaughtering steps. Differential log counts changed consistently with the steps. The measurements, including the patterns in their inherently random variability, were fairly predictable from steps 1 and 4. The results indicated that differential log counts for TC and EC are not relevant, as their concentrations and random pattern can be inferred from counts of MA and EB. The proposed model can be used as a valuable tool for the design and adoption of feasible quality control programs in beef industries. The adoption of such a tool should have a positive contribution on consumers’ health and enhance product quality.
Virulence, antibiotic resistance and biogenic amines of bacteriocinogenic lactococci and enterococci isolated from goat milk
(International Journal of Food Microbiology, 2014-06-12) Perin, Luana Martins; Miranda, Rodrigo Otávio; Todorov, Svetoslav Dimitrov; Franco, Bernadette Dora Gombossy de Melo; Nero, Luís Augusto
The present study aimed to investigate the virulence, antibiotic resistance and biogenic amine production in bacteriocinogenic lactococci and enterococci isolated from goat milk in order to evaluate their safety. Twenty-nine bacteriocinogenic lactic acid bacteria (LAB: 11 Lactococcus spp., and 18 Enterococcus spp.) isolated from raw goat milk were selected and subjected to PCR to identify gelE, cylA, hyl, asa1, esp, efaA, ace, vanA, vanB, hdc1, hdc2, tdc and odc genes. The expression of virulence factors (gelatinase, hemolysis, lipase, DNAse, tyramine, histamine, putrescine) in different incubation temperatures was assessed by phenotypic methods, as well as the resistance to vancomycin, gentamicin, chloramphenicol, ampicillin and rifampicin (using Etest®). The tested isolates presented distinct combinations of virulence related genes, but not necessarily the expression of such factors. The relevance of identifying virulence-related genes in bacteriocinogenic LAB was highlighted, demanding for care in their usage as starter cultures or biopreservatives due to the possibility of horizontal gene transfer to other bacteria in food systems.