Teses e Dissertações
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/1
Teses e dissertações defendidas no contexto dos programas de pós graduação da Instituição.
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Resultados da Pesquisa
Item Modelling of the Staphylococcus aureus growth and enterotoxin a production based on different conditions(Universidade Federal de Viçosa, 2023-11-30) Silva, Mírian Pereira da; Nero, Luís Augusto; http://lattes.cnpq.br/5283983143131663Staphylococcus aureus is one of the pathogens most involved in food outbreaks. Enterotoxigenic S. aureus produce enterotoxins stable at high temperatures. This is a concern for dairy products, like Minas frescal cheese, since enterotoxins can be produced in early stages of production (raw milk) and remain stable after thermic treatments, like pasteurization. Therefore, it is necessary to adopt appropriate measures to prevent contamination and the eventual toxins production. Predictive microbiology is a powerful tool for food safety and quality. Using mathematical models, it is possible to predict the behavior of microorganisms under specific conditions. Given that Minas frescal cheese is strongly associated with S. aureus, mathematical models are relevant to demonstrate how bacterial growth and enterotoxins production are influenced by production and storage conditions. Thus, this study aimed to characterize the physicochemical aspects and the presence of S. aureus in Minas frescal cheese and, based on this data, create predictive models of growth and the production of enterotoxin A by S. aureus. Samples of Minas frescal cheese (n = 50) were obtained and subjected to pH, sodium chloride concentration, and temperature analysis. The presence and characterization of Staphylococcus spp. were evaluated, and coagulase-positive isolates were investigated for the presence of the nuc gene for S. aureus identification and enterotoxin genes (sea, seb, sec, sed, see). Based on this data, growth models (Combase and response surface model) and enterotoxin production models (probabilistic logistic regression model) were developed and statistically and experimentally validated. All coagulase-positive isolates tested were confirmed as S. aureus, and none presented genes related to enterotoxins. The pH, temperature, and salt concentration varied from 5.80 to 6.62, from 5 °C to 12 °C, and from 0.85% to 1.70%, respectively. The model generated by Combase assessed the influence of temperature, pH, and salt concentration on the growth kinetics (maximum growth rate and lag time) of S. aureus and found values ranging from 0.012 to 0.419 log CFU/mL/h of growth rate and adaptation time from 4.60 to 159.24 hours. Temperature was the factor that most influenced the growth kinetics, and salt concentration did not significantly influence the responses. Subsequently, response surface models and logistic regression models were developed to assess the growth responses of S. aureus and the probability of enterotoxin A (SEA) production, respectively. In addition to the factors assessed in the growth kinetics, different levels of initial contamination of S. aureus and time were incorporated into the models. With the exception of sodium chloride concentration, all factors significantly affected the growth and production of enterotoxin A by S. aureus. The maximum population obtained ranged from 8.27 to 9.36 log CFU/mL at 25 °C and from 3.90 to 8.27 log CFU/mL at 15 °C. At 10 °C, at the lowest contamination level evaluated, S. aureus (100 CFU/mL) remained below the detection limit (<1.0 CFU/mL) throughout incubation, and no SEA production occurred, while for the other concentrations (103 CFU/mL and 105 CFU/mL), the maximum population was 7.79 CFU/mL, highlighting the importance of maintaining Minas frescal cheese at refrigeration temperatures and controlling the initial contamination level. SEA production occurred for all conditions evaluated at 15 °C and 25 °C, but at different times. The models showed a good fit to the experimental data, with satisfactory values for R² (0.90), accuracy factor (1.09), and bias factor (0.99) for the growth model; a high agreement percentage (94.4%), Nagelkerke's R² (0.92), and the Hosmer and Lemeshow test (p > 0.05) for the SEA production model. Additionally, experimental validation in culture media, milk, and cheese confirmed that the models are suitable for predicting the growth and the probability of SEA production by S. aureus in Minas frescal cheese. Keywords: Staphylococcus aureus. Enterotoxin A. Minas frescal cheese. Predictive microbiology. Mathematical models.Item Genomic characterization and antimicrobial activity of Pediococcus pentosaceus ST65ACC(Universidade Federal de Viçosa, 2023-10-06) Oliveira, Francielly Soares; Nero, Luís Augusto; http://lattes.cnpq.br/9531426576646370The bacteriocinogenic strain Pediococcus pentosaceus ST65ACC was previously isolated from Brazilian artisan cheese (BAC) and showed strong bactericidal activity against Listeria monocytogenes. This strain also showed beneficial properties, such as the ability to survive gastrointestinal conditions and to aggregate with L. monocytogenes, indicating it as a potential probiotic candidate. The present study aimed to genomically characterize the P. pentosaceus ST65ACC strain through whole-genome sequencing (WGS), analyzing its technological and beneficial properties, bacteriocin clusters, and safety profiles, and also evaluating its antimicrobial activity against L. monocytogenes Scott A in different culture media. The genome of P. pentosaceus ST65ACC comprises 1,933,194 bp witha GC content of 37.00 %, and contains1,950 protein coding sequences (CDSs) with 62 RNA genes (6 rRNA, 55 tRNA, 1 tmRNA). Genomic analysis revealed the presence of operons that encode the bacteriocins pediocin PA-1/AcH and penocin-A, and also identified the presence of genes related to beneficial properties, such as stress adaptation genes and adhesion genes. Regarding the strain safety profiles, genes encoding biogenic amines and virulence genes were not detected. Genes related to antibiotic resistance were identified in the genome, but not in prophage regions, and no plasmids were detected, thus presenting a low risk of transferring to other bacteria. The results obtained fromthe interaction of P. pentosaceus ST65ACC and L. monocytogenes Scott A in MRS broth, BHI broth, milk, and meat broth for 96 h showed that the antimicrobial activity of the strain was more effective in MRS broth. L. monocytogenes was inhibited toun detectable levels by the strain in MRS broth during the 96 h of analysis, with high levels of bacteriocin production (3,200 – 12,800 AU/ml) being identified. However, lower inhibitory activities were recorded in BHI, milk, and meat broth, with low or no production of bacteriocins at the times analyzed. Thus, verifying that the composition of the media can interfere with the production/activity of bacteriocins and, consequently, with the antagonistic activity of P. pentosaceus ST65ACC on L. monocytogenes Scott A. The results obtained through genomic characterization confirmed the beneficial potential and safety of P. pentosaceus ST65ACC, indicating that this strain can be considered suitable for application in food biopreservation, as well as a promising probiotic candidate. Keywords: Pediococcus. Biopreservation. Bacteriocins. Pediocin. Genomic analysis.Item Bioprospecting of enzymes from fungi isolated from Canastra cheeses for industrial application(Universidade Federal de Viçosa, 2022-05-10) Lopes, Isabelle Lima; Martin, José Guilherme Prado; http://lattes.cnpq.br/8032710337190002The microbial diversity of Brazilian artisanal cheeses is far from being fully explored. Among frequently isolated microorganisms, bacteria and fungi stand out. Filamentous fungi can be highlighted for their significant impact in the quality of surface mould-ripened cheeses, besides that several metabolites produced, including enzymes. Fungal enzymes are widely used in industry, due to the easier extraction and purification compared to other enzymes sources. In this context, the aim of this study was to evaluate the proteolytic and lipolytic activity of 58 filamentous fungi isolated from artisanal cheeses produced in Canastra region, Minas Gerais State, Brazil. Submerged fermentation assays were performed considering casein as a protease inducer and olive oil as a lipase-inducing substrate. The proteolytic activity was evaluated by the caseinolytic method using a spectrophotometric assay; lipolytic activity, by potentiometric titration of fatty acids released by fungi lipases. Penicillium steckii and Aspergillus versicolor showed the highest proteolytic activity, with with 31.14 U/mL and 29.35 U/mL, respectively. Regarding lipolytic activity, Geotrichum candidum and Penicillium steckii presented the highest activities, with 62.91 U/mL and 55.44 U/mL, respectively. Considering the results of the proteolytic activity and their potential use in the dairy industry, a Geotrichum candidum isolate (GC-31) was selected and submitted to ultraviolet light (UV) mutation induction assay; then, the mutants obtained were evaluated for proteolytic activity. In total, 18 mutant strains were obtained; GC-M10 showed an increase in proteolytic activity up to 274% (29.96 U/mL) in comparison to the wild type (10.94 U/mL); therefore, the UV induction method was efficient in increasing the enzymatic activity of the isolated evaluated. This study showed that fungi isolated from artisanal cheeses produced in Canastra region have potential for biotechnological exploration and the production of industrial enzymes. Keywords: Protease.Lipase. Canastra cheese.Geotrichum candidum.Mutante.Epifluorescence microscopy.Item Produção de kombucha a partir de diferentes inóculos brasileiros(Universidade Federal de Viçosa, 2022-02-25) Venturim, Bárbara Côgo; Martin, José Guilherme Prado; http://lattes.cnpq.br/4187987053098634Kombucha é uma bebida obtida pela fermentação de chá (Camellia sinensis) por um inóculo popularmente conhecido como SCOBY (Symbiotic Culture Of Bacteria and Yeast). No Brasil, a cultura de doações de SCOBY entre os produtores é amplamente difundida; somada às diferentes condições de fermentação, a diversidade de inóculos resulta em bebidas com características distintas. Neste trabalho, 30 amostras de SCOBY de diferentes regiões brasileiras foram utilizadas para produção de kombucha. No decorrer de 10 dias de fermentação, análises de pH e acidez total titulável (ATT) foram determinadas. As populações de leveduras, bactérias acéticas (BAA) e do ácido lático (BAL) dos inóculos foram quantificadas ao término da fermentação. O teor de acidez volátil e as concentrações de ácido acético, ácido glicônico, ácido lático e etanol foram determinadas, assim como as concentrações de sacarose, glicose e frutose residuais. Por fim, foram realizadas análises de rendimento, produtividade volumétrica e capacidade de retenção de água do material celulósico gerado após o período de fermentação. O pH das bebidas variou entre 2,38 e 4,82; a ATT entre 0,02 e 1,96% (p/v) e a acidez volátil entre 0,89 e 32,2 mEq/L. O ácido glicônico foi identificado como o principal ácido nas kombuchas, variando de 3,12 a 6,78% (p/v), seguido do ácido acético (0,18 a 0,53% p/v) e ácido lático (0,01 a 0,08% p/v). Todas as kombuchas apresentaram baixo teor alcoólico, com exceção de K15 (0,83% v/v). Os açúcares residuais da kombucha variaram de 0,28 a 5,16% (p/v) para sacarose; 0,53 a 1,73% (p/v) para glicose e 0,22 e 1,44% (p/v) para frutose. As contagens dos grupos microbianos majoritários variaram de 6,68 a 10,03 Log UFC/g para BAA; de 6,48 a 9,35 Log UFC/g para BAL; e de 6,03 a 9,48 Log UFC/g para leveduras. Apesar da síntese de celulose bacteriana (CB) durante a fermentação da kombucha, a produtividade volumétrica foi relativamente baixa nas condições de fermentação avaliadas (0,001 a 0,012 g/L.h); em contrapartida, a capacidade de retenção de água foi alta (máxima de 98,54%). Tendo em vista a crescente produção industrial de kombucha e celulose bacteriana, os resultados obtidos neste trabalho podem contribuir para um maior entendimento acerca dos impactos dos parâmetros fermentativos na qualidade da bebida, bem como no rendimento da produção do material celulósico. Palavras-chave: Bebida fermentada. SCOBY. Celulose bacteriana.Item Fungal biodiversity in dairy industry and antifungal activity of lactic acid bacteria in cheese matrix(Universidade Federal de Viçosa, 2023-02-17) Souza, Luana Virginia; Carvalho, Antonio Fernandes de; http://lattes.cnpq.br/3018973720636920Spoilage fungi contamination in dairy industries represents an important economic problem due to spoilage of products. In addition, due to the mycotoxins produced by some fungi, it may also represent a public health problem. Considering the current demand for lesser chemical preservatives addition in foods associated to “Clean label” tendency, the application of bioprotective cultures has been widely explored as alternative. Bacteria belonging to the group of lactic acid bacteria (LAB) stand out as possible bioprotective cultures for being widely used in food processing, show antagonist activity against spoilage microorganisms, and some species recognized as GRAS (Generally Recognized As Safe) status. Thus, considering the concern with spoilage fungi in the dairy industry and the ways to prevent these contaminations, this thesis aimed to understand the biodiversity of fungi in the dairy chain and the antifungal activity of some LAB. For that, the construction of this thesis was realized in two steps: (1) 109 filamentous fungi were isolated from spoiled dairy products and dairy production environments and identified through sequencing of the internal transcribed spacer (ITS) region; (2) 52 LAB strains were tested In vitro for their antifungal potential against Aspergillus niger and Penicillium chrysogenum and LAB with the highest antifungal activity were selected for the in situ test into cheese matrix inoculated with A. niger and P. chrysogenum. As result, Penicillium and Cladosporium were the most frequent genera isolated from spoilage dairy products. Cladosporium, Penicillium, Aspergillus, and Nigrospora had high incidence in the processing environment. Four species (Hypoxylon griseobrunneum, Rhinocladiella similis, Coniochaeta rosae, and Paecilomyces maximus) were identified for the first time in dairy environments. Three phytopathogenic genera (Montagnula, Clonostachys, and Riopa) and one pathogenic fungi (R. similis) were also identified. Regarding the phylogeny, 14 families and most of the fungi belonging to the Ascomycota phylum were observed. For the antifungal activity in vitro test, 5 strains of LAB (W. confusa (W5, W8), W. paramesenteroides (W9), W. cibaria (W25), L. Plantarum (Q4C3)) had the highest antifungal effect against the target fungi. In general, the five strains had a positive antifungal effect against A. niger and P. Chrysogenum also in the in situ test; however, these strains lose, in different intensities, their antifugal activity in cheese matrix when combined with a starter culture. Thereby, we show with our study that, despite someLAB didn’t present an antifungal effect when combined with the starter culture, it is important to emphasize that these bacteria may have great antifungal potential when apply in other food matrices which don’t use a starter culture. Finally, they can be tested regarding their other diverse technological applications. Keywords: Dairy products. Antifungal activity. Spoilage fungal. Biopreservation. Biodiversity.Item Pseudomonas spp. causing spoilage in Brazilian cheeses by pigment production(Universidade Federal de Viçosa, 2022-12-19) Rodrigues, Rafaela da Silva; Nero, Luís Augusto; http://lattes.cnpq.br/7362224677469106Cheeses are foods prone to the growth of spoilage microorganisms, such as Pseudomonas: one of the most complex and diverse genera of Gram-negative bacteria, which makes it difficult to correctly assign strains to the species. Reports in recent years have shown that some strains belonging to this genus are capable of producing a blue pigment that is diffusible in dairy products with a high moisture content, in cold storage. Therefore, research has tried to elucidate aspects related to the production of this pigment, as well as the genomic region related to this phenotype, however there are still contradictions between their results. Here, we identified blue pigment-producing Pseudomonas strains isolated from spoiled samples of Minas Frescal cheese and processed cheese “requeijão em barra”, and used whole-genome sequencing (WGS) and bioinformatics tools to aid in the studies. For the first time, Pseudomonas strains that cause blue discoloration in Brazilian cheeses were investigated and identified. We found Pseudomonas carnis and Pseudomonas paracarnis as pigment producers, with rapid production at refrigerated temperatures and at 25 °C. Strains obtained here are phylogenetically related to others already investigated in other countries, and bioinformatics analysis helped to identify a genomic region of 74 genes, contained only in pigment producers, which includes tryptophan biosynthesis genes (trpABCDF) and genes for mobile genetic elements (MGE) such as genes involved in horizontal gene transfer (e. g., pilM, pilV, pilX, tadA, traD). This region has also been identified by bioinformatics tools as an integrative and conjugative element (ICE), due to components related to conjugative-transposon-like mobile genetic elements and it has plasmid- like conjugative properties. Furthermore, a phylogenomic investigation of strains confirmed as P. carnis, deposited in GenBank, showed that there is no evolutionary relationship between those that are pigmenting and carriers of duplicated trpABCDF genes, all of which are isolated only from food. With this, it appears that the recent spoilage in food reported in different countries may not have been caused by the spread of a single strain. Therefore, studies like this help to understand an issue that is affecting different nationalities, as well as providing a basis for the development of markers that will allow the tracking and control of these spoilers in food.In addition, it shows that a correct bacterial identification at the species level is essential for a reliable execution of investigations, when it comes to Pseudomonas. Keywords: Pseudomonas. Spoilage. Blue discoloration. Genomic analysis.Item Detection and control of Pseudomonas using phage and phage protein(Universidade Federal de Viçosa, 2019-07-22) Carvalhais, Jéssica Fernandes; Eller, Monique Renon; http://lattes.cnpq.br/9435202715961859Bacteria from the genus Pseudomonas plays an important role in milk, meat and fish spoilage because it can produce thermo-tolerant lipolytic and proteolytic enzymes, which reduce both the quality and shelf life this product. Besides this, the colonization of these bacteria can in many cases facilitate the colonization of pathogenic bacteria and the formation of biofilms. Chapter 2 aims to develop a rapid technique based on affinity for the identification of Pseudomonas in liquid solutions and in biofilms by agglutination. For this, magnetic beads were affinity linked to a structural phage protein from the UFV-P2 phage, that is responsible for recognition and binding to structures in the bacterial cell membrane. This complex formed by the beads and the structural phage protein, when in contact with the bacteria Pseudomonas fluorescens and Pseudomonas aeruginosa tend to form agglutinates visible to the naked eye. The test developed was able to identify P. fluorescens and P. aeruginosa. The test developed was able to identify P. fluorescens and P. aeruginosa in solution after 30 s and 3 min respectively. The tests were negative for Pseudomonas putida. Lactococcus lactis, Listeria monocytogenes and Escherichia coli. The lowest detectable concentration of P. fluorescens in solutions was 10³ CFU-mL-¹ and 10⁴ CFU-mL-¹ for P. aeruginosa. The tests on biofilms of P. fluorescens the agglutination was observed in the first minute of contact and in the P. aeruginosa biofilms after 2 min. There was no difference in agglutination time in biofilms with 24 and 48 h of formation in both strains analyzed. Biofilms with 72 h showed slower agglutination, presenting a time of agglutination between 4 to 5 min. The agglutination test was negative in biofilms of E. coli. The tests with swab solution presented positive agglutination after 3 min of contact. The agglutination test was considered efficient for solutions containing P. fluorescens and P. aeruginosa also for identification in biofilms on stainless steel coupons. The agglutination test developed was classified as fast response and specific for P. fluorescens and P. aeruginosa. The development of technologies that allow the rapid detection of microorganisms is an important strategy for quality control in industries and safety of the population. Chapter 3 of this thesis describes the use of phage P10 to control and prevent biofilm formation. The objective of this study was to evaluate the effects of adding phage P10 during P. fluorescens biofilm formation. The effects of P10 on pre-formed biofilm on polystyrene plates after 6 h of contact and over the course of 48 h were also examined. In both cases the phage activity was evaluated under static and dynamic condition at room temperature. The titers of the bacteria and phage were 10⁵ CFU-mL-¹ and 10⁸ PFU.mL-¹, respectively. Phage P10 significantly reduced (p<0.05) the number of adhered cells during the biofilm formation and in pre-formed biofilm under static and dynamic condition. The phage activity was more effective in younger biofilms. Adding phages during the biofilm formation resulted in an average 2.5-log reduction in the number of adhered cells. When the phages were added to pre-formed biofilm at 12 h, there was a 1.2 log reduction in the number of adhered cells. The use of phage P10 for these purposes is becoming increasingly relevant in terms of pathogenic bacterial resistance to the sanitizers that are traditionally used in food industries. Using the P10 phage to control biofilm formation may be a promising alternative for use in the food industry. The use of phages or their proteins is an important tool for industries and studies that elucidate efficiency and applications in different areas are increasingly relevant. The results of this thesis show that the use of phage and phage proteins has positive results regarding its applicability in biotechnologyItem Estudo da fermentação em co-cultura de leveduras Saccharomyces e não-Saccharomyces para produção de cervejas(Universidade Federal de Viçosa, 2019-10-10) Pereira Junior, Paulo Cesar da Silva; Luera Peña, Wilmer Edgard; http://lattes.cnpq.br/3013915832712364As cervejas especiais que apresentam diversificação de sabores e aromas estão ganhando espaço no mercado. Nesse sentido, o uso de técnicas inovadoras de produção tornou-se essencial para o atendimento ao mercado. O uso de leveduras não-Saccharomyces tem sido aplicado de forma isolada ou em co-cultura com a tradicional Saccharomyces cerevisiae de modo a obter cervejas de características únicas. Dessa forma, este trabalho teve objetivo de avaliar o uso de diferentes proporções entre leveduras não-Saccharomyces (Pichia anomala, Candida apicola e Torulaspora delbrueckii) em co-cultura com S. cerevisiae em diferentes concentrações iniciais do mosto na elaboração de cervejas. Para isto, foi realizado um delineamento composto central rotacional. Foi utilizado a técnica de citometria de fluxo na avaliação das proporções entre as leveduras, cromatografia líquida de alta eficiência na quantificação de açúcares, glicerol e etanol, cromatografia a gás na avaliação dos compostos voláteis e por fim, foi realizado uma avaliação sensorial com beer sommeliers das cervejas oriundas dos ensaios com teor de etanol otimizado. Na co- cultura com S. cerevisiae e T. delbrueckii, esta última dominou a fermentação quando inoculada em proporções acima de 1:100. A produção de etanol máxima desta co- cultura foi de 6,07% (v/v). Na co-cultura entre S. cerevisiae e P. anomala, foi observado competição entre elas na maior parte dos ensaios com predomínio da S. cerevisiae após 5 dias de fermentação, sendo a concentração máxima de etanol atingida de 3,92% (v/v). A co-cultura entre S. cerevisiae e C. apicola, bem como da cultura pura de S. cerevisiae, tiveram produção máxima de etanol de 5,09 e 3,31% (v/v), respectivamente. O perfil de voláteis ficou caracterizado por uma alta produção de acetato de etila nas co-culturas envolvendo P. anomala. As fermentações conduzidas com T. delbrueckii não apresentaram teores de voláteis superiores ao ensaio controle, não trazendo a característica frutada esperada. Os compostos álcool 2-feniletil, 1-propanol e álcool isobutílico ficaram com concentrações abaixo do limiar de percepção em todas as condições testadas, ao contrário do álcool isoamílico e octanoato de etila. As cervejas foram avaliadas sensorialmente e caracterizadas com sabor e aroma doce alto, devido ao resíduo de extrato não consumido na fermentação. No atributo frutado/ésteres, a nota mais alta foi para a cerveja produzida na co-cultura com C. apicola, e a menor nota para a cerveja elaborada em co-cultura com T. delbrueckii. No geral as cervejas tiveram notas baixas para os atributos referentes a defeitos, indicando que as condições impostas de fermentação e todo processo de produção foram conduzidas de forma adequada. Assim, o uso de leveduras não- Saccharomyces em co-cultura com S. cerevisiae pode ser uma alternativa para a produção de cervejas especiais. Palavras-chave: Cervejas especiais. Compostos aromáticos. Torulaspora delbrueckii. Pichia anomala. Candida apicola.Item Atividade do extrato fenólico de pitanga sobre a formação de biofilmes por Serratia liquefaciens(Universidade Federal de Viçosa, 2019-04-17) Rodrigues, Adeline Conceição; Andrade, Nélio José de; http://lattes.cnpq.br/1767453920395179Biofilme é um conglomerado de células aderidas a uma superfície, envolvidas em uma matriz de exopolímeros (EPS). É resistente a antimicrobianos tornando difícil sua erradicação. Alternativas para o controle do biofilme estão sendo pesquisadas e os compostos naturais têm apresentado importantes resultados ao interferirem na comunicação pelo mecanismo de quorum sensing. Visando avaliar o efeito de concentrações sub-inibitórias (sub-MIC) do extrato fenólico de pitanga (Eugenia uniflora L.; EFP) sobre a formação de biofilme de Serratia liquefaciens L53. Pitangas foram coletadas, despolpadas e realizou-se a extração purificando os compostos fenólicos utilizando extração em fase sólida (mini-coluna C18). Os compostos fenólicos totais foram quantificados pelo ensaio do reagente Folin-Ciocalteu, identificados por análise em cromatografia líquida de alta eficiência (CLAE) e por Chromatography Electrospray Ionization Tandem Mass Spectrometric (LC-ESI-MS/MS) e a concentração inibitória mínima (MIC) para S. liquefaciens L53. Foram determinadas as concentrações sub-MIC foram avaliadas sobre a formação de biofilme total e sobre os componentes da matriz do biofilme nos tempos de 7, 48 e 168 h. Foi avaliada a susceptibilidade do biofilme de 48 h formado na presença do EFP a agentes antimicrobianos e seu efeito combinado com os antibióticos ampicilina (30 μg.mL -1 ), canamicina (10 μg.mL -1 ) e getamicina (10 μg.mL -1 ). O EFP apresentou 231 mg de ácido gálico equivalente (AGE). 100 g -1 de polpa de compostos fenólicos totais e os flavonoides majoritários identificados foram elagitaninos e derivados glicosilados de quercetina. Em concentrações sub-MIC, o EFP diminuiu a formação do biofilme total e os componentes da matriz dos EPS, polissacarídeos, proteínas e DNA, nos tempos de 7 e 48 h e, em contrapartida, aumentou em 168 h. O EFP não alterou o número de células viáveis de S. liquefaciens L53 aderidas ao poliestireno no tempo de 48 h nem a susceptibilidade ao tratamento com 200 mg.L -1 de dicloroisocianurato e 0,1 mg.mL -1 de canamicina comparados ao controle. O EFP, em uso combinado com os antibióticos, apresentou efeito antagônico com os mesmos. Nesse contexto, o uso de concentraçãos sub-MIC do EFP apresentou efeitos divergentes na formação do biofilme em função do tempo de análise, diminuindo o biofilme em menor tempo e aumentando em tempo maior de cultivo. O EFP não alterou a susceptibilidade do biofilme ao tratamento com antimicrobianos comparado ao controle e atuou como antagonista com antibióticos. Sendo assim, a utilização do EFP é controversa, pois pode apresentar efeitos indesejáveis, aumentando o biofilme no tempo maior de contato, além de apresentar efeito antagônico com antibióticos.Item Caracterização da microbiota lática do Queijo Minas artesanal produzido na região do Serro, Minas Gerais, por métodos cultura dependente e independente(Universidade Federal de Viçosa, 2021-07-30) Ferreira, Letícia Rocha; Nero, Luís Augusto; http://lattes.cnpq.br/8686469253395668Queijos Minas artesanais (QMA) possuem importância social, econômica e cultural para inúmeras famílias de produtores rurais. QMA são tradicionalmente produzidos em várias regiões de Minas Gerais com leite cru e fermento endógeno, “pingo”, derivado de sua dessoragem. Além da produção tradicional, alguns produtores da região do Serro utilizam “rala” como fermento endógeno, obtida pela raspagem do QMA após 3-5 dias de fabricação. A alteração do fermento endógeno pode levar a alterações da microbiota do QMA, incluindo a microbiota lática que exerce papel fundamental na produção, maturação, desenvolvimento de características sensoriais, bioconservação e inocuidade. O conhecimento da microbiota lática autóctone do QMA auxilia na caracterização de sua identidade, permitindo sua consolidação como símbolo regional. O estudo da microbiota de alimentos fermentados usualmente é realizado por métodos cultura-dependentes, limitados pela microbiota complexa e pelo cultivo de parte da microbiota. Como alternativa, métodos cultura-independentes têm sido cada vez mais utilizados; esses métodos também possuem algumas limitações, como dificuldade de diferenciação entre microrganismos viáveis e não viáveis. A abordagem ideal para a caracterização da microbiota de queijos artesanais é a associação de métodos cultura- dependentes e -independentes de cultivo. Esse estudo teve como objetivo caracterizar a microbiota lática autóctone do QMA do Serro com diferentes características de produção por métodos cultura-dependentes e -independentes de cultivo. Amostras de QMA do Serro (n = 55) foram obtidas na Cooperativa dos Produtores Rurais do Serro (CooperSerro) e caracterizadas quanto ao fermento endógeno (“pingo” e “rala”), cidade produtora (Alvorada de Minas, Sabinópolis, Santo Antônio do Imbé, Serra Azul de Minas e Serro), tamanho da fazenda produtora (produção diária de leite) e tempo de produção (dias). As amostras foram submetidas a enumeração de bactérias ácido láticas (BAL) em ágar MRS, pH 5,7 e obtenção de isolados (n = 176) que foram caracterizados por Repetitive extragenic palindromic-PCR (Rep-PCR) e identificados por sequenciamento da região V1-V3 do 16S rRNA. Em paralelo, as amostras foram submetidas a extração de DNA total para caracterização da diversidade microbiana por Rep-PCR, Denaturing Gradient Gel Eletrophoresis (DGGE) e sequenciamento da região V3-V4 do 16S rRNA. A contagem de BAL em amostras e QMA do Serro variaram entre 5,4 e 8,4 log UFC/g com um valor médio de 6,9 log UFC/g, e os principais grupos/gêneros identificados foram lactobacilos, Lactococcus lactis e Enterococcus sp.; não foram identificadas tendências nas contagens e distribuição de BAL considerando as características das amostras. Rep-PCR identificou semelhanças intraespécies superiores a 75%. O sequenciamento das bandas de DGGE identificou a prevalência de L. lactis em todas as amostras, além de Streptococcus salivarius. Considerando o DNA total das amostras, L. lactis foi identificado como espécie dominante em todas as amostras. Rep-PCR e DGGE provaram ser ferramentas úteis para estudar a microbiota lática de queijos artesanais. A abordagem integrada dos métodos cultura- dependente e -independente forneceu uma descrição mais detalhada da diversidade lática presente no QMA do Serro. A microbiota lática do QMA do Serro possui uma composição estável, sem variações evidentes considerando as características de produção avaliadas. Palavras-chave: Bactérias ácido láticas. Pingo. Rala. Cultura-dependente. Cultura-independente. Sequenciamento.