Veterinária
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11842
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Resultados da Pesquisa
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 Potential Control of Listeria monocytogenes by Bacteriocinogenic Enterococcus hirae ST57ACC and Pediococcus pentosaceus ST65ACC Strains Isolated From Artisanal Cheese(Probiotics and Antimicrobial Proteins, 2019-03) Cavicchioli, Valéria Quintana; Camargo, Anderson Carlos; Todorov, Svetoslav Dimitrov; Nero, Luís AugustoBacteriocinogenic Enterococcus hirae ST57ACC and Pediococcus pentosaceus ST65ACC strains, previously isolated from artisanal cheese, were evaluated for their safety with the aim to determine whether they could be used as beneficial strains, especially in the control of Listeria monocytogenes. Both isolates survived simulated gastrointestinal conditions and showed high levels of auto- and co-aggregation with L. monocytogenes, although the hydrophobicity of cells varied. Using the agar-spot test with 33 commercial drugs from different groups, only anti-inflammatory drugs and drugs containing loratadine and propranolol hydrochloride were able to affect the growth of the tested strains. Both strains were resistant to 3 out of 11 antibiotics tested by the disc diffusion method, and low frequencies of antibiotic resistance-encoding genes were observed by PCR analysis. Tested strains neither presented biogenic amine-related genes nor produced these substances. Aside from some antibiotic resistance characteristics, the tested strains were considered safe as they lack other virulence-related genes. E. hirae ST57ACC and P. pentosaceus ST65ACC both presented beneficial properties, particularly their ability to survive gastrointestinal conditions and to aggregate with L. monocytogenes, which can facilitate the elimination of this pathogen. Further studies should be conducted to better understand these interactions.Item Lactobacillus curvatus UFV-NPAC1 and other lactic acid bacteria isolated from calabresa, a fermented meat product, present high bacteriocinogenic activity against Listeria monocytogenes(BMC Microbiology, 2019) Castilho, Nathália Parma Augusto; Colombo, Monique; Oliveira, Leandro Licursi de; Todorov, Svetoslav Dimitrov; Nero, Luís AugustoBacteriocins produced by lactic acid bacteria (LAB) can be considered as viable alternatives for food safety and quality, once these peptides present antimicrobial activity against foodborne pathogens and spoilage bacteria. Fermented foods, such as artisanal sausages and cured meats, are relevant sources of LAB strains capable of producing novel bacteriocins, with particular interest by the food industry.Three LAB strains (firstly named as Lactobacillus curvatus 12, L. curvatus 36 and Weissella viridescens 23) were obtained from calabresa by presenting promising bacteriocinogenic activity, distinct genetic profiles (rep-PCR, RAPD, bacteriocin-related genes) and wide inhibitory spectrum. Among these strains, L. curvatus 12 presented higher bacteriocin production, reaching 25,000 AU/mL after incubation at 25, 30 and 37 °C and 6, 9 and 12 h. Partially purified bacteriocins from L. curvatus 12 kept their inhibitory activity after elution with isopropanol at 60% (v/v). Bacteriocins produced by this strain were purified by HPLC and sequenced, resulting in four peptides with 3102.79, 2631.40, 1967.06 and 2588.31 Da, without homology to known bacteriocins.LAB isolates obtained from calabresa presented high inhibitory activity. Among these isolates, bacteriocins produced by L. curvatus 12, now named as L. curvatus UFV-NPAC1, presented the highest inhibitory performance and the purification procedures revealed four peptides with sequences not described for bacteriocins to date.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 Occurrence and characterization of Listeria monocytogenes from beef jerky processing line(Journal of Food Science and Technology, 2019-01) Silva, Danilo Augusto Lopes da; Nero, Luís Augusto; Coradini, Marcia Goulart Lopes; Maia, Darla Silveira Volcan; Iglesias, Mariana Almeida; Haubert, Louise; Lopes, Graciela VolzBeef jerky is a ready-to-eat product that does not require refrigeration at the point of sale. Here, we evaluated the occurrence of Listeria monocytogenes in the production process of beef jerky, the presence of virulence genes and the genomic relatedness of the isolates, to assess the safety of the final product. The raw material, surfaces with and without contact with the product and the final product were evaluated along the beef jerky processing line. The samples were evaluated by VIDAS immunoassay system, and the L. monocytogenes isolates were confirmed and evaluated for the presence of several virulence genes by PCR. Listeria monocytogenes was identified in six of the 84 samples (7.14%), and no genetic relationship was observed among isolates. Samples of raw material (2/7), food contact surface (1/56), and work surfaces without contact with food (3/14) presented contamination by L. monocytogenes. The final product was not contaminated, demonstrating that barriers to multiplication of pathogens used during the production process were effective for its control.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 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 Low occurrence of Salmonella in the beef processing chain from Minas Gerais state, Brazil: From bovine hides to end cuts(Food Control, 2014-06) Cossi, Marcus Vinícius Coutinho; Burin, Raquel Cristina Konrad; Camargo, Anderson Carlos; Dias, Mariane Rezende; Lanna, Frederico Germano Piscitelli Alvarenga; Pinto, Paulo Sérgio de Arruda; Nero, Luís AugustoThe present study aimed to track possible contamination sources of Salmonella spp. during bovine slaughtering. Three slaughterhouses located in Minas Gerais state, Brazil were selected and 836 samples were obtained by surface swabbing of 209 bovine carcasses at four steps of slaughtering: I) after bleeding (from the hide), II) after skinning, III) after evisceration, and IV) after end washing (performed with cold water). Samples were subjected to Salmonella spp. detection according to ISO 6975, and the suspected isolates were identified by PCR as Salmonella by targeting the ompC gene and performing serotyping. Twenty isolates were confirmed as Salmonella and subjected to XbaI macrorestriction and pulsed-field gel electrophoresis (PFGE). Salmonella spp. was detected in the hides of six animals, during slaughtering after skinning (one carcass), after evisceration (two carcasses), and after end washing (three carcasses). Isolates were serotyped as S. Dublin (n = 7), S. Derby (n = 8), S. Infantis (n = 1), S. Give (n = 1), and S. salamae subsp. salamae (n = 3). PFGE demonstrated identical Salmonella pulse-types from hides and slaughtering steps of skinning and evisceration, as well as from animal hides obtained from distinct slaughterhouses. The obtained data indicate a low prevalence of Salmonella spp. during bovine slaughtering in selected industries from Minas Gerais state, Brazil, but identified possible routes of contamination of pathogenic serotypes.Item Influence of lactic acid and acetic acid on Salmonella spp. growth and expression of acid tolerance-related genes(Food Research International, 2014-08-23) Burin, Raquel Cristina Konrad; Silva Jr., Abelardo; Nero, Luís AugustoSalmonella spp. is an important foodborne pathogen, often associated with meat products. This pathogen presents a complex tolerance mechanism in the presence of organic acids, which is regulated by a diversity of genes, including rpoS, nlpD and clpP. The present study aimed to measure the expression of such genes by Salmonella strains subjected to acid stress conditions, and associate these data with microbial growth. A culture collection composed of 79 strains of Salmonella spp. obtained from bovine and swine production chains was subjected to PFGE using XbaI, and 3 strains (serovars Derby, Typhimurium and Meleagridis) were selected for acid tolerance trials. The selected strains were inoculated in meat extract broth (MEB) added to lactic or acetic acids at a final pH of 4.0, 5.0 or 6.0, and incubated at 37 °C for 6, 12, 24 and 48 h. As controls, Salmonella strains were inoculated in MEB at pH 7.0, and incubated in the same conditions. Bacterial populations were monitored by direct plating and gene expression using qPCR. Salmonella presented similar populations to controls and evident expression of rpoS at pH 5.0 and 6.0. However, Salmonella populations were not detectable after 6 h at pH 4.0. The adaptability of Salmonella to pH 5.0 and 6.0 emphasizes the importance of adequate monitoring of pH reduction during cleaning procedures in food industries, such as organic acid spraying in bovine carcasses. The data obtained demonstrated the relevance of rpoS in the acid tolerance mechanism of Salmonella strains, prompting further studies to investigate its expression in meat systems.Item Protocols for the isolation and detection of lactic acid bacteria with bacteriocinogenic potential(LWT - Food Science and Technology, 2010-11) Moraes, Paula Mendonça; Perin, Luana Martins Perin; Ortolani, Maria Beatriz Tassinari; Yamazi, Anderson Keizo; Viçosa, Gabriela Nogueira; Nero, Luís AugustoThe objective of this study was to evaluate culture media and methodologies for isolation and detection of lactic acid bacteria (LAB) capable to produce bacteriocin-like substances. Samples of milk and cheese were pour plated on de Mann-Rogosa-Sharpe agar (MRS) and Kang-Fung-Sol agar (KFS) (both at 35 °C/48 h, under anaerobiosis), from which 389 and 256 LAB cultures were selected. The antagonistic activity of them was evaluated using the spot-on-the-lawn and two culture media: brain-heart infusion agar with catalase (BHI + C) and M17 (both at 35 °C/24 h). The proteinaceous nature of the antagonistic cultures was verified using: spot-on-the-lawn (MRS, 25 °C/24 h, under anaerobiosis) and well-diffusion (cultures amplified on modified MRS broth at 25 °C/24 h, and then neutralized using NaOH). Listeria monocytogenes ATCC 7644 was used as indicator. A larger number of antagonist cultures were isolated from MRS (83 by M17 and 65 by BHI + C) in comparison to KFS (24 by M17 and 15 by BHI + C). The spot-on-the-lawn identified a higher frequency of LAB capable of producing bacteriocin-like substances. MRS was considered to be the best culture media for the isolation of LAB capable to produce bacteriocin-like substances, activity that was better identified using the spot-on-the-lawn methodology.