Navegando por Autor "Nero, Luís Augusto"
Agora exibindo 1 - 20 de 45
- Resultados por Página
- Opções de Ordenação
Item Adequacy of Petrifilm™ Aerobic Count plates supplemented with de Man, Rogosa & Sharpe broth and chlorophenol red for enumeration of lactic acid bacteria in salami(Meat Science, 2015-07-17) Castilho, Natália Parma Augusto de; Okamura, Vivian Tiemi; Camargo, Anderson Carlos; Pieri, Fábio Alessandro; Nero, Luís AugustoThe present study aimed to assess the performance of alternative protocols to enumerate lactic acid bacteria (LAB) in salami. Fourteen cultures and two mixed starter cultures were plated using six protocols: 1) Petrifilm™ Aerobic Count (AC) with MRS broth and chlorophenol red (CR), incubated under aerobiosis or 2) under anaerobiosis, 3) MRS agar with CR, 4) MRS agar with bromocresol purple, 5) MRS agar at pH 5.7, and 6) All Purpose Tween agar. Samples of salami were obtained and the LAB microbiota was enumerated by plating according protocols 1, 2, 3 and 5. Regression analysis showed a significant correlation between the tested protocols, based on culture counts (p < 0.05). Similar results were observed for salami, and no significant differences of mean LAB counts between selected protocols (ANOVA, p > 0.05). Colonies were confirmed as LAB, indicating proper selectivity of the protocols. The results showed the adequacy of Petrifilm™ AC supplemented with CR for the enumeration of LAB in salami.Item Análise e monitoramento de pontos críticos no abate de frangos utilizando indicadores microbiológicos(Ciência Rural, 2008-10) Pinto, Paulo Sérgio de Arruda; Vanetti, Maria Cristina Dantas; Bevilacqua, Paula Dias; Nero, Luís Augusto; Pinto, Mayara Souza; Rodrigues, Augusto César AlmeidaA presença de microrganismos indicadores de contaminação na linha de abate de frangos foi determinada visando identificar os possíveis pontos de controle e oferecer uma opção para o monitoramento ou a verificação pelo sistema “Análise de Perigos e Pontos Críticos de Controle” (APPCC). A contaminação superficial das carcaças foi determinada pela enumeração de microrganismos aeróbios mesófilos, coliformes totais, coliformes termotolerantes e de Escherichia coli nas seguintes fases de abate: A - antes do primeiro chuveiro de higienização, B - após o primeiro chuveiro, C - após a evisceração manual, D - após o chuveiro de lavagem final e E - na saída do pré-resfriamento. Não houve diferença significativa (P<0,05) entre as médias de mesófilos, coliformes totais e termotolerantes, entre as fases A, B, C e D. Entretanto, as médias obtidas para esses microrganismos indicadores na fase E (pré-resfriamento) foram significativamente menores. Não houve diferença significativa entre as médias de Escherichia coli nas cinco fases. As chances de contaminação (Razão de Chances) por mesófilos foram maiores na fase A e por coliformes na fase C. Entre os parâmetros analisados, os níveis de contaminação por mesófilos, coliformes totais e termotolerantes foram os mais indicados para monitoramento e verificação de um plano APPCC no abate de aves. Os resultados obtidos indicaram que a fase de pré-resfriamento pode ser considerada um importante ponto crítico de controle, uma vez que foi capaz de reduzir a contaminação microbiológica de forma significativa.Item Antagonistic lactic acid bacteria isolated from goat milk and identification of a novel nisin variant Lactococcus lactis(BMC Microbiology, 2014-02-06) Perin, Luana Martins; Nero, Luís AugustoThe raw goat milk microbiota is considered a good source of novel bacteriocinogenic lactic acid bacteria (LAB) strains that can be exploited as an alternative for use as biopreservatives in foods. The constant demand for such alternative tools justifies studies that investigate the antimicrobial potential of such strains. The obtained data identified a predominance of Lactococcus and Enterococcus strains in raw goat milk microbiota with antimicrobial activity against Listeria monocytogenes ATCC 7644. Enzymatic assays confirmed the bacteriocinogenic nature of the antimicrobial substances produced by the isolated strains, and PCR reactions detected a variety of bacteriocin-related genes in their genomes. Rep-PCR identified broad genetic variability among the Enterococcus isolates, and close relations between the Lactococcus strains. The sequencing of PCR products from nis-positive Lactococcus allowed the identification of a predicted nisin variant not previously described and possessing a wide inhibitory spectrum. Raw goat milk was confirmed as a good source of novel bacteriocinogenic LAB strains, having identified Lactococcus isolates possessing variations in their genomes that suggest the production of a nisin variant not yet described and with potential for use as biopreservatives in food due to its broad spectrum of action.Item Antibiotic resistance of Listeria monocytogenes isolated from meat-processing environments, beef products, and clinical cases in Brazil(Microbial Drug Resistance, 2015) Camargo, Anderson Carlos; Castilho, Natalia Parma Augusto de; Silva, Danilo Augusto Lopes da; Vallim, Deyse Christina; Hofer, Ernesto; Nero, Luís AugustoThe present study aimed to assess the antimicrobial resistance and the presence of virulence markers in 137 Listeria monocytogenes isolates obtained from meat-processing environments, beef products, and clinical cases. All isolates were subject to molecular serogrouping and their antibiotic resistance profiles were assessed against 12 antimicrobials. In addition, isolates were subjected to detection of virulence marker genes (inlA, inlC, inlJ). The isolates were classified into serogroups 4b, 4d, 4a, or 4c (46%), 1/2c or 3c (27%), 1/2a or 3a (13.9%), and 1/2b or 3b (13.1%). All tested isolates presented sensitivity to the majority of the tested antimicrobials, but most of them presented resistance or intermediate resistance to clindamycin (88.3%) and oxacillin (73.7%). Virulence markers were detected in all isolates, demanding further analysis to better characterize their pathogenic potential.Item Bacterial ecology of artisanal Minas cheeses assessed by culture-dependent and -independent methods(Food Microbiology, 2017-02-12) Nero, Luís Augusto; Perin, Luana Martins; Sardaro, Maria Luisa Savo; Neviani, Erasmo; Gatti, MonicaArtisanal Minas cheese is produced in Minas Gerais state, Brazil and its varieties are named according to their geographical origin (Serro, Canastra, Serra do Salitre, Araxá and Campo das Vertentes). The cheese is produced with raw cow's milk and the whey from the previous cheese production (“pingo”). The high economic and cultural importance of artisanal cheese in Brazil justifies the efforts to ensure its safety, quality and provenance. This study aimed to characterize the microbial diversity composition, and geographical distribution of artisanal Minas cheese, focusing on the characterization of its autochthonous lactic acid bacteria (LAB) microbiota. Artisanal Minas cheese varieties from Serro, Canastra, Serra do Salitre, Araxá and Campo das Vertentes were analyzed by culture-dependent (culturing and LAB sequencing) and -independent (repetitive extragenic palindromic-PCR (rep-PCR) and length heterogeneity-PCR, LH-PCR) methods to characterize the microbiota. The microbial counts were variable between cheese samples, and some samples presented high number of coagulase positive bacteria and coliforms that may be associated with hygienic issues. In all samples was observed a prevalence of LAB. 16S rRNA sequencing and rep-PCR of the LAB strains identified four genus (Lactobacillus, Lactococcus, Enterococcus and Weissella), ten species and more than one strain per species. Lactobacillus was the most prevalent genera in all the cheeses. LH-PCR revealed a further six genera and ten species that were not identified by culturing, highlighting the importance of combining both culture-dependent and -independent methods to fully characterize microbiota diversity. Principal component analysis of the LH-PCR data and cluster analysis of rep-PCR data revealed that the artisanal Minas cheese microbiota was influenced not only by their geographical origin but also by the cheese farm. The lack of standardization in the milking and cheese manufacturing procedures between artisanal cheese farms could explain the microbial diversity.Item Beneficial properties of lactic acid bacteria naturally present in dairy production(BMC Microbiology, 2018-12) Colombo, Monique; Castilho, Nathália P. A.; Todorov, Svetoslav D.; Nero, Luís AugustoConsumers are increasingly demanding for natural and beneficial foods, in order to improve their health and well-being. Probiotics play an important role in such demand, and dairy foods are commonly used as vehicles for such bacteria, represented predominantly by lactic acid bacteria. Due to consumers demand, food industry is constantly looking for novel bacterial strains, leading to studies that aims the isolation and characterization of their beneficial features. This study aimed to characterize the naturally occurring lactic acid bacteria obtained from a dairy environment, in order to assess their potential use as probiotics.Preliminary screening and PCR analysis, based on 16S rRNA sequencing, were applied to select and identify 15 LAB strains from the genera Lactobacillus (n = 11), Pediococcus (n = 2) and Weissella (n = 2). All strains showed resistance to low pH and the evaluated bile salt concentrations in vitro. The API ZYM test characterized the enzymatic activity of the strains, and a high β-galactosidase activity was observed in 13 strains. All strains presented resistance to simulated gastric (3 h) and intestinal (4 h) conditions in vitro, the ability to auto- and co-aggregate with indicator microorganisms and a high cell surface hydrophobicity. Most of the strains were positive for map and EFTu beneficial genes. All strains exhibited strong deconjugation of bile salts in vitro and all assimilated lactose.The phenotypes exhibited in vitro and the presence of beneficial genes revealed the beneficial potential of the studied strains, demanding further analyses in a food matrix and in vivo to allow the development of a functional product, with health-related properties.Item Comparison of destructive and nondestructive sampling techniques of retail chicken carcasses for enumeration of hygiene indicator microorganisms(Journal of Food Protection, 2012-01) Cossi, Marcus Vinícius Coutinho; Almeida, Michelle Vieira de; Dias, Mariane Rezende; Pinto, Paulo Sérgio de Arruda; Nero, Luís AugustoThe type of sampling technique used to obtain food samples is fundamental to the success of microbiological analysis. Destructive and nondestructive techniques, such as tissue excision and rinsing, respectively, are widely employed in obtaining samples from chicken carcasses. In this study, four sampling techniques used for chicken carcasses were compared to evaluate their performances in the enumeration of hygiene indicator microorganisms. Sixty fresh chicken carcasses were sampled by rinsing, tissue excision, superficial swabbing, and skin excision. All samples were submitted for enumeration of mesophilic aerobes, Enterobacteriaceae, coliforms, and Escherichia coli. The results were compared to determine the statistical significance of differences and correlation (P < 0.05). Tissue excision provided the highest microbial counts compared with the other procedures, with significant differences obtained only for coliforms and E. coli (P < 0.05). Significant correlations (P < 0.05) were observed for all the sampling techniques evaluated for most of the hygiene indicators. Despite presenting a higher recovery ability, tissue excision did not present significant differences for microorganism enumeration compared with other nondestructive techniques, such as rinsing, indicating its adequacy for microbiological analysis of chicken carcasses.Item Comparison of phenotypic and molecular tests to identify lactic acid bacteria(Brazilian Journal of Microbiology, 2012-07-02) Moraes, Paula Mendonça; Perin, Luana Martins; Silva Júnior, Abelardo; Nero, Luís AugustoTwenty-nine lactic acid bacteria (LAB) isolates were submitted for identification using Biolog, API50CHL, 16S rDNA sequencing, and species-specific PCR reactions. The identification results were compared, and it was concluded that a polyphasic approach is necessary for proper LAB identification, being the molecular analyzes the most reliable.Item Desempenho do ELISA no diagnóstico da cisticercose utilizando bovinos experimentalmente e naturalmente infectados com o metacestódeo de Taenia saginata(Semina: Ciências Agrárias, 2014-07-18) Guimarães-Peixoto, Rafaella Paola Meneguete dos; Pinto, Paulo Sérgio de Arruda; Nero, Luís Augusto; Santos, Tatiane de Oliveira; Silva, Letícia Ferreira da; Acevedo-Nieto, Emílio Campos; Rivetti Júnior, Anselmo VasconcelosO complexo teníase-cisticercose bovina pode ser definido como um conjunto de alterações patológicas causadas pela forma adulta da Taenia saginata no humano e por sua forma larvar nos bovinos (Cysticercus bovis). Dados sobre a ocorrência da cisticercose bovina provêm dos registros de inspeção veterinária de carnes em matadouros-frigoríficos inspecionados, onde alguns casos positivos podem passar despercebidos, principalmente em infecções moderadas, tornando-se relevante a utilização de testes sorológicos com maior sensibilidade que o exame post-mortem de rotina. Estudos demonstram a possível aplicação do teste ELISA como ferramenta para estudos epidemiológicos da parasitose e na identificação dos animais portadores de cistos. O objetivo do presente trabalho foi avaliar o desempenho e determinar o limiar de detecção de um ELISA indireto, utilizando animais experimentalmente e naturalmente infectados na detecção de casos de cisticercose. A sensibilidade do teste para animais naturalmente infectados utilizando o ponto de corte 1 e 2 adicionados de 2 SD foi de 12% e 24,4% respectivamente. Contudo quanto utilizado o ponto de corte 1 e 2 adicionados de 3 SD a sensibilidade do teste teve uma queda, representado 1,99% e 14,4%. Já para as amostras de animais experimentalmente infectados utilizando o ponto de corte 1 e 2 adicionados de 2 SD, a sensibilidade ficou em 55,9% e 92,5% e adicionando 3 SD foram encontrados os valores de 31,2% e 86% respectivamente. A especificidade do teste em todas as situações testadas ficou em 100%. É importante levar em consideração a escolha certa dos soros-controle utilizados no teste ELISA, visto que de acordo com sua aplicação torna-se necessário elevar a sensibilidade ou especificidade do teste.Item Destructive and nondestructive procedures to obtain chicken carcass samples for Escherichia coli and Salmonella spp. detection(Foodborne Pathogens and Disease, 2011-11) Cossi, Marcus Vinícius Coutinho; Almeida, Michelle Vieira de; Dias, Mariane Rezende; Pinto, Paulo Sérgio de Arruda; Nero, Luís AugustoDestructive and nondestructive sampling procedures were compared for Escherichia coli and Salmonella spp. detection in 60 fresh chicken carcasses, which were submitted to the following sampling procedures: rinsing, skin swabbing, tissue excision, and skin excision; the proximity or not to the cloacae region was also considered. The obtained results were compared to identify significant differences (p<0.05). Forty eight chicken carcasses were positive for E. coli, and five were positive for Salmonella spp. For E. coli, nonsignificant differences were observed between rinsing and tissue excision, rinsing and skin excision, and skin excision and tissue excision (p>0.05), thus indicating equivalencies between these techniques. Skin swabbing produced a statistically significant lower frequency of positive results (p<0.05) than all other techniques for E. coli, thus indicating its inadequacy for detection of this microorganism. For Salmonella spp., no significant differences were observed between the sampling techniques (p>0.05), possibly due to the low overall frequency of positive carcasses. No significant differences in the number of positive samples (E. coli or Salmonella spp.) were observed between samples collected near or far from the cloacae region (p>0.05), regardless of the sampling technique. The obtained results demonstrate that the tested sampling techniques were equivalent for Salmonella spp. detection in chicken carcasses, as observed for E. coli with the exception of skin swabbing.Item Development of a selective culture medium for bifidobacteria, Raffinose-Propionate Lithium Mupirocin (RP-MUP) and assessment of its usage with PetrifilmÔ Aerobic Count plates(Food Microbiology, 2013-11-26) Miranda, Rodrigo Otávio; Carvalho, Antonio Fernandes de; Nero, Luís AugustoThis study aimed to develop a selective culture media to enumerate bifidobacteria in fermented milk and to assess this medium when used with PetrifilmÔ AC plates. For this purpose, Bifidobacterium spp., Lactobacillus spp. and Streptococcus thermophilus strains were tested to verify their fermentation patterns for different carbohydrates. All bifidobacteria strains were able to use raffinose. Based on these characteristic, a selective culture medium was proposed (Raffinose-Propionate Lithium Mupirocin, RP-MUP), used with PetrifilmÔ AC plates, and was used to enumerate bifidobacteria in fermented milk. RP-MUP performance was assessed by comparing the results with this medium to reference protocols and culture media for bifidobacteria enumeration. RP-MUP, whether used or not with PetrifilmÔ AC, presented similar performance to TOS-MUP (ISO 29981), with no significant differences between the mean bifi dobacteria counts (p < 0.05) and with high correlation indices (r 1⁄4 0.99, p < 0.05). As an advantage, reliable results were obtained after just 48 h of incubation when RP-MUP was used with PetrifilmÔ AC, instead of the 72 h described in the ISO 29981 protocol.Item Development of a selective culture medium for bifidobacteria, Raffinose-Propionate Lithium Mupirocin (RP-MUP) and assessment of its usage with Petrifilm™ Aerobic Count plates(Food Microbiology, 2014-05) Miranda, Rodrigo Otávio; Carvalho, Antonio Fernandes de; Nero, Luís AugustoThis study aimed to develop a selective culture media to enumerate bifidobacteria in fermented milk and to assess this medium when used with Petrifilm™ AC plates. For this purpose, Bifidobacterium spp., Lactobacillus spp. and Streptococcus thermophilus strains were tested to verify their fermentation patterns for different carbohydrates. All bifidobacteria strains were able to use raffinose. Based on these characteristic, a selective culture medium was proposed (Raffinose-Propionate Lithium Mupirocin, RP-MUP), used with Petrifilm™ AC plates, and was used to enumerate bifidobacteria in fermented milk. RP-MUP performance was assessed by comparing the results with this medium to reference protocols and culture media for bifidobacteria enumeration. RP-MUP, whether used or not with Petrifilm™ AC, presented similar performance to TOS-MUP (ISO 29981), with no significant differences between the mean bifidobacteria counts (p < 0.05) and with high correlation indices (r = 0.99, p < 0.05). As an advantage, reliable results were obtained after just 48 h of incubation when RP-MUP was used with Petrifilm™ AC, instead of the 72 h described in the ISO 29981 protocol.Item egc characterization of enterotoxigenic Staphylococcus aureus isolates obtained from raw milk and cheese(International Journal of Food Microbiology, 2013-08-01) Viçosa, Gabriela Nogueira; Loir, Alban Le; Loir, Yves Le; Carvalho, Antônio Fernandes de; Nero, Luís AugustoGenes encoding staphylococcal enterotoxins (SEs) are carried by mobile genetic elements, and enterotoxin gene clusters (egc) are pathogenicity island-borne structures comprising several SE genes, which are frequently found among clinical Staphylococcus aureus isolates. In the present study, we investigated the distribution and the genetic variability of egc loci in S. aureus strains isolated from raw milk and soft cheese in Minas Gerais, Brazil. Ninety-two isolates were submitted to PCR detection of individual egc-borne SE genes (seg, sei, sem, sen, seo, seu), and egc loci were typed using PCR-RFLP. PCR products of egc positive isolates were sequenced. Ninety-one isolates harbored at least one SE gene, which generated 14 different genotypes. The sei gene was the most widely distributed (97.8%), and was found in combination with seg in 49 isolates (53.3%). Altogether, a complete set of individual egc genes was detected in 37 isolates (40%). However, egc loci were detected by PCR-RFLP in only 4 isolates, and classified as egc1 (n = 2), egc3 (n = 1), and egc4 (n = 1). This investigation demonstrated the low occurrence of the egc in S. aureus isolated from dairy products. However, the frequency of complete sets of individual egc-borne genes reflects either the presence of these SE genes outside egc or the existence of new egc types in these strains.Item Enumeration of bifidobacteria using Petrifilm™ AC in pure cultures and in a fermented milk manufactured with a commercial culture of Streptococcus thermophilus(Food Microbiology, 2011-07-21) Miranda, Rodrigo Otávio; Gama Neto, Gabriel; Freitas, Rosangela de; Carvalho, Antônio Fernandes de; Nero, Luís AugustoBifidobacteria are probiotic microorganisms that are widely used in the food industry. With the aim of using of Petrifilm™ Aerobic Count (AC) plates associated with selective culture media, aliquots of sterile skim milk were inoculated separately with four commercial cultures of bifidobacteria. These cultures were plated by both the conventional method and Petrifilm™AC, using the culture media NNLP and ABC. The cultures were incubated under anaerobiosis at 37 °C for 24, 48 and 72 h. No significant differences (p > 0.05) were observed between the obtained counts at 48 and 72 h. Bifidobacteria counts in ABC were usually higher than in NNLP, independent of the plating method. Subsequently, fermented milk was prepared with a Streptococcus thermophilus strain, and aliquots were inoculated with the same bifidobacteria. Then, the fermented milks were submitted to microbiological analysis for bifidobacteria enumeration using the same culture media and methodologies previously described, incubated under anaerobiosis at 37 °C for 48 h. Again, bifidobacteria counts in ABC were higher than in NNLP, with significant differences for some cultures (p < 0.05). The counts obtained by both methodologies presented significant correlations (p < 0.05). The results indicate the viability of Petrifilm™AC as an alternative method for bifidobacteria enumeration when associated to specific culture media, specially the ABC.Item Enumeration of bifidobacteria using PetrifilmTM AC in pure cultures and in a fermented milk manufactured with a commercial culture of Streptococcus thermophilus(Food Microbiology, 2011-07-21) Miranda, Rodrigo Otávio; Freitas, Rosangela de; Carvalho, Antônio Fernandes de; Nero, Luís Augusto; Gama Neto, GabrielBifidobacteria are probiotic microorganisms that are widely used in the food industry. With the aim of using of PetrifilmÔ Aerobic Count (AC) plates associated with selective culture media, aliquots of sterile skim milk were inoculated separately with four commercial cultures of bifidobacteria. These cultures were plated by both the conventional method and PetrifilmÔAC, using the culture media NNLP and ABC. The cultures were incubated under anaerobiosis at 37 C for 24, 48 and 72 h. No significant differences (p > 0.05) were observed between the obtained counts at 48 and 72 h. Bifidobacteria counts in ABC were usually higher than in NNLP, independent of the plating method. Subsequently, fermented milk was prepared with a Streptococcus thermophilus strain, and aliquots were inoculated with the same bifidobacteria. Then, the fermented milks were submitted to microbiological analysis for bifidobacteria enumeration using the same culture media and methodologies previously described, incubated under anaerobiosis at 37 C for 48 h. Again, bifidobacteria counts in ABC were higher than in NNLP, with significant differences for some cultures (p < 0.05). The counts obtained by both methodologies presented significant correlations (p < 0.05). The results indicate the viability of PetrifilmÔAC as an alternative method for bifidobacteria enumeration when associated to specific culture media, specially the ABC.Item Enumeration of coagulase and thermonuclease-positive Staphylococcus spp. in raw milk and fresh soft cheese: an evaluation of Baird-Parker agar, Rabbit Plasma Fibrinogen agar and the Petrifilm™ Staph Express count system(Food Microbiology, 2010-01-04) Viçosa, Gabriela Nogueira; Moraes, Paula Mendonça; Yamazi, Anderson Keizo; Nero, Luís AugustoStaphylococcus spp. are microorganisms that are naturally present in milk and dairy products and are often associated with food-borne diseases outbreaks due to the ability of some strains to produce thermostable enterotoxins. This ability is usually associated with coagulase and thermonuclease production, characteristics that are considered in the microbiological analyses for the control of such microorganisms. The objective of this study was to evaluate the culture media and the methodologies used for the enumeration of coagulase and thermonuclease-positive Staphylococcus spp. in raw milk and fresh soft cheese. Samples of artificially contaminated milk (with coagulase-positive Staphylococcus reference strains) and samples of naturally contaminated raw milk and cheese were submitted for enumeration in Baird-Parker agar (BP), Rabbit Plasma Fibrinogen agar (RPFA) and in the PetrifilmÔ Staph Express count system (STX). No significant differences (P > 0.05) were observed between the mean counts obtained in all of the evaluated culture media. RPFA and STX had good correlation indices between the total and typical colony counts as well as with coagulase and the thermonuclease-positive colony counts. Thus, there is a better association between coagulase and thermonuclease production to typical colony morphology developed on these culture media, leading to more accurate and reliable results than with BP, which demonstrated lower correlation indices between these counts.Item Evaluation of target sequences for the polymerase chain reaction–based detection of salmonella in artificially contaminated beef(Foodborne Pathogens and Disease, 2014-01-23) Almeida, Michelle Vieira de; Nero, Luís Augusto; Silva Jr., AbelardoSalmonella is a major cause of foodborne diseases worldwide, which has fueled the demand for the development and evaluation of sensitive, specific, and rapid detection methodologies, such as polymerase chain reaction (PCR). In this study, six primer pairs for the detection of Salmonella were evaluated by PCR with isolates of Salmonella spp. (115) and other bacteria (104). The primers designed for the sifB gene provided the best performance regarding specificity and sensitivity (100%). These primers were selected and used to develop a PCR assay for Salmonella detection during the enrichment steps of the conventional detection method in spiked beef samples. The enrich- ment steps were: buffered peptone water (BPW), Rappaport-Vassiliadis soya broth (RVS) and at the Mu ̈ller- Kauffmann tetrathionate novobiocin broth (MKTTn), after 18 h (BPW) and 24 h (RVS and MKTTn) of incubation. The initial concentrations of the Salmonella inocula were 10 1 , 10 2 , and 10 3 colony-forming units/25 g. The protocol was able to detect Salmonella at all concentrations in the enrichment steps, but not in the nonenriched samples. These results indicated that the proposed protocol was suitable to detect Salmonella in beef during the intermediate stages of the conventional isolation protocol, substantially reducing the time required to obtain the final results.Item Expression of genes associated with stress conditions by Listeria monocytogenes in interaction with nisin producer Lactococcus lactis(Food Research International, 2017-12-13) Miranda, Rodrigo Otávio; Campos-Galvão, Maria Emilene Martino; Nero, Luís AugustoThe use of nisin producers in foods is considered a mitigation strategy to control foodborne pathogens growth, such as Listeria monocytogenes, due to the production of this bacteriocin in situ. However, when the bacteriocin does not reach an adequate concentration, the target bacteria can develop a cross-response to different stress conditions in food, such as acid, thermal and osmotic. This study aimed to evaluate the interaction of a nisin-producing strain of Lactococcus lactis DY-13 and L. monocytogenes in BHI and skim milk, and its influence on general (sigB), acid (gadD2), thermal (groEL) and osmotic (gbu) stress-related genes of the pathogen. L. monocytogenes populations decreased approximately 2 log in BHI and 1 log in milk after 24 h in co-culture with the nisin producer L. lactis, coherent with the increasing expression of nisK. Expression of stress-related genes by L. monocytogenes presented lower oscillation in BHI than in milk, indicating its better ability to survive in milk, despite the higher nisin production. Stress-related genes presented a varied expression by L. monocytogenes in the tested conditions: sigB expression remained stable or reduced over time; gadD2 presented high expression in milk; groEL presented low expression in BHI when compared to milk, trending to decrease overtime; gbu expression in milk after 24 h was lower than in BHI. The presented study demonstrated the growth of a nisin producer L. lactis can affect the expression of stress-related genes by L. monocytogenes, and understating these mechanisms is crucial to enhance the conservation methods employed in foods.Item Functional properties of Lactobacillus mucosa e strains isolated from brazilian goat milk(Probiotics and Antimicrobial Proteins, 2016-12-10) Nero, Luís Augusto; Todorov, Svetoslav Dimitrov; Moraes, Georgia Maciel Dias de; Abreu, Louricélia Rodrigues de; Egito, Antônio Silvio do; Salle, Hévila Oliveira; Silva, Liana Maria Ferreira da; Santos, Karina Maria Olbrich dosThe search for probiotic candidates among lactic acid bacteria (LAB) isolated from food may uncover new strains with promising health and technological properties. Lactobacillus mucosae strains attracted recent research attention due to their ability to adhere to intestinal mucus and to inhibit pathogens in the gastrointestinal tract, both related to a probiotic potential. Properties of interest and safety aspects of three Lb. mucosae strains (CNPC006, CNPC007, and CNPC009) isolated from goat milk were investigated employing in vitro tests. The presence of genetic factors related to bile salt hydrolase production (bsh), intestinal adhesion properties (msa, map, mub, and ef-tu), virulence, and biogenic amine production were also verified. All strains exhibited the target map, mub, and ef-tu sequences; the msa gene was detected in CNPC006 and CNPC007 strains. Some of the searched sequences for virulence factors were detected, especially in the CNPC009 strain; all strains carried the hyl gene, related to the production of hyaluronidase. Lb. mucosae CNPC007 exhibited a high survival rate in simulated gastric and enteric conditions. Besides, all strains exhibited the bsh sequence, and CNPC006 and CNPC007 were able to deconjugate salts of glycodeoxycholic acid (GDC). Regarding technological properties for dairy product applications, a relatively higher milk acidification and clotting capacity, diacetyl production, and proteolytic activity were registered for CNPC007 in comparison to the other strains. Collectively, the results aim at Lb. mucosae CNPC007 as a promising probiotic candidate for application in dairy products, deserving further studies to confirm and explore its potential.Item Functional properties of Lactobacillus mucosae strains isolated from brazilian goat milk(Probiotics and Antimicrobial Proteins, 2016-12-10) Nero, Luís Augusto; Moraes, Georgia Maciel Dias de; Abreu, Louricélia Rodrigues de; Egito, Antônio Silvio do; Salles, Hévila Oliveira; Silva, Liana Maria Ferreira da; Todorov, Svetoslav Dimitrov; Santos, Karina Maria Olbrich dosThe search for probiotic candidates among lactic acid bacteria (LAB) isolated from food may uncover new strains with promising health and technological properties. Lactobacillus mucosae strains attracted recent research attention due to their ability to adhere to intestinal mucus and to inhibit pathogens in the gastrointestinal tract, both related to a probiotic potential. Properties of interest and safety aspects of three Lb. mucosae strains (CNPC006, CNPC007, and CNPC009) isolated from goat milk were investigated employing in vitro tests. The presence of genetic factors related to bile salt hydrolase production (bsh), intestinal adhesion properties (msa, map, mub, and ef-tu), virulence, and biogenic amine production were also verified. All strains exhibited the target map, mub, and ef-tu sequences; the msa gene was detected in CNPC006 and CNPC007 strains. Some of the searched sequences for virulence factors were detected, especially in the CNPC009 strain; all strains carried the hyl gene, related to the production of hyaluronidase. Lb. mucosae CNPC007 exhibited a high survival rate in simulated gastric and enteric conditions. Besides, all strains exhibited the bsh sequence, and CNPC006 and CNPC007 were able to deconjugate salts of glycodeoxycholic acid (GDC). Regarding technological properties for dairy product applications, a relatively higher milk acidification and clotting capacity, diacetyl production, and proteolytic activity were registered for CNPC007 in comparison to the other strains. Collectively, the results aim at Lb. mucosae CNPC007 as a promising probiotic candidate for application in dairy products, deserving further studies to confirm and explore its potential.
- «
- 1 (current)
- 2
- 3
- »