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Serratia liquefaciens is a spoilage microorganism of relevance in the dairy industry because it is psychrotrophic, able to form biofilm, and produces thermoresistant proteases and lipases. Phenolic compounds and furanones have been studied as inhibitors of biofilm formation. In this study, the potential of the pulp phenolic extract of Eugenia uniflora L. orange fruits, also called pitanga, and furanone C30 on the inhibition of biofilm formation by S. liquefaciens L53 and the susceptibility to different antimicrobials were evaluated. The pulp phenolic extract of pitanga had a high total phenolic content, being mainly composed of glycosylated quercetins and ellagitannins. Sub-inhibitory concentrations of this extract and furanone reduced biofilm formation by S. liquefaciens on polystyrene and the amount of polysaccharides, proteins and extracellular DNA in the biofilms. These biofilms were also more susceptible to kanamycin. The combinations of furanone with phenolic extract of pitanga or kanamycin showed a synergistic effect with total growth inhibition of S. liquefaciens.

Edible coatings have several advantages in preserving foods, such as avoiding water loss, controlling microbial growth, and reducing the need for preservatives added directly to the product. Antimicrobial action can be obtained by adding antimicrobial substances including phenolic compounds commonly found in plant extracts. This study evaluated the phenolic compounds content, antioxidant and antimicrobial activity of pulp, and seed extracts of

Salmonella is an important foodborne pathogen, and it is unable to produce the quorum sensing signaling molecules called acyl-homoserine lactones (AHLs). However, it synthesizes the SdiA protein, detecting AHL molecules, also known as autoinducer-1 (AI-1), in the external environment. Exogenous AHLs can regulate specific genes related to virulence and stress response in Salmonella. Thus, interfering with quorum sensing can be a strategy to reduce virulence and help elucidate the cell-to-cell communication role in the pathogens' response to extracellular signals. This study aimed to evaluate the influence of the quorum sensing inhibitors furanone and phytol on phenotypes regulated by N-dodecanoyl homoserine lactone (C12-HSL) in Salmonella enterica serovar Enteritidis. The furanone C30 at 50 nM and phytol at 2 mM canceled the alterations promoted by C12-HSL on glucose consumption and the levels of free cellular thiol in Salmonella Enteritidis PT4 578 under anaerobic conditions. In silico analysis suggests that these compounds can bind to the SdiA protein of Salmonella Enteritidis and accommodate in the AHL binding pocket. Thus, furanone C30 and phytol act as antagonists of AI-1 and are likely inhibitors of the quorum sensing mechanism mediated by AHL in Salmonella.

Edible coatings have several advantages in preserving foods, such as avoiding water loss, controlling microbial growth, and reducing the need for preservatives added directly to the product. Antimicrobial action can be obtained by adding antimicrobial substances including phenolic compounds commonly found in plant extracts. This study evaluated the phenolic compounds content, antioxidant and antimicrobial activity of pulp, and seed extracts of Mimusopsis comersonii (popularly known in Brazil as abrico), besides the phenolic compounds were identified and quantified in the pulp extract. Edible coatings were incorporated with pulp extract in order to evaluate the preservation of minimally processed apples and baroa potatoes against foodborne bacteria, and enzymatic browning was also determined. Myricetin-3-glucoside, quercetin-3-glucoside, and kaempferol-3-glucoside were identified as major flavonoids in the apricot pulp extract. The seed and pulp extracts inhibited all tested microorganisms, especially Staphylococcus aureus and Salmonella Typhimurium. Edible coatings added with 9% of phenolic extract showed in vitro antimicrobial activity, in addition to being effective in preventing enzymatic browning in minimally processed apples and baroa potatoes for up to 15 days of storage. They were also effective in reducing up to 2 log CFU/g of aerobic mesophiles after 15 days of storage for apples, even though no microbial inhibition in baroa potatoes was observed under the same conditions. The addition of pulp phenolic extract in edible coatings proved to be an alternative in the preservation of apples and in the antibrowning activity of minimally processed baroa potatoes.

The emergence of multidrug-resistant bacteria stimulates the search for new substitutes to traditional antimicrobial agents, especially molecules with antivirulence properties, such as those that interfere with quorum sensing (QS). This study aimed to evaluate the potential of phenolic compounds for QS inhibition in a QS biosensor strain (Chromobacterium violaceum) and three foodborne bacterial species (Aeromonas hydrophila, Salmonella enterica serovar Montevideo, and Serratia marcescens). Initially, an in silico molecular docking study was performed to select the compounds with the greatest potential for QS inhibition, using structural variants of the CviR QS regulator of C. violaceum as target. Curcumin, capsaicin, resveratrol, gallic acid, and phloridizin presented good affinity to at least four CviR structural variants. These phenolic compounds were tested for antimicrobial activity, inhibition of biofilm formation, and anti-QS activity. The antimicrobial activity when combined with kanamycin was also assessed. Curcumin, capsaicin, and resveratrol inhibited up to 50% of violacein production by C. violaceum. Biofilm formation was inhibited by resveratrol up to 80% in A. hydrophila, by capsaicin and curcumin up to 40% in S. Montevideo and by resveratrol and capsaicin up to 60% in S. marcescens. Curcumin completely inhibited swarming motility in S. marcescens. Additionally, curcumin and resveratrol increased the sensitivity of the tested bacteria to kanamycin. These results indicate that curcumin and resveratrol at concentrations as low as 6μM are potential quorum sensing inhibitors besides having antimicrobial properties at higher concentrations, encouraging applications in the food and pharmaceutical industries.

Phenolic compounds (PC) have presented antioxidant potential as well as antimicrobial action against several bacteria. This study aimed to extract PC from grumixama (Eugenia brasiliensis Lam.) pulp using solid phase extraction (SPE), then quantify the PC by Folin-Ciocalteu assay, and to evaluate the antioxidant activity (AA) from PC by DPPH, ABTS and FRAP methods as well as its antimicrobial activity by plate diffusion assay (PDA) and Minimal Inhibitory Concentration (MIC) assays. Additionally, the centesimal composition of the fruit and its mineral content by Total Reflection X-Ray Fluorescence Spectroscopy were determined. The fruit is a good source of PC which presented a higher contribution on AA from pulp than NPHRC. Calcium was the trace element in highest concentration in the pulp, followed by iron. PC from grumixama inhibited the growth of Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa but not Escherichia coli and Listeria monocytogenes in the PDA. PC showed antimicrobial activity against the five microorganisms tested in the MIC assay, in which S. aureus and B. cereus were the most sensitive. This study highlights the antioxidant and antimicrobial potential of Eugenia brasiliensis Lam. as natural agent in the development of functional foods and nutraceuticals.

Endogenous starter cultures are used in the production of several cheeses around the world, such as Parmigiano-Reggiano, in Italy, Époisses, in France, and Canastra, in Brazil. These microbial communities are responsible for many of the intrinsic characteristics of each of these cheeses. Bacteriophages are ubiquitous around the world, well known to be involved in the modulation of complex microbiological processes. However, little is known about phage–bacteria growth dynamics in cheese production systems, where phages are normally treated as problems, as the viral infections can negatively affect or even eliminate the starter culture during production. Furthermore, a recent metagenomic based meta-analysis has reported that cheeses contain a high abundance of phage-associated sequences. Here, we analyse the viral and bacterial metagenomes of Canastra cheese, a tradition artisanal cheese produced using an endogenous starter culture. We observe a very high phage diversity level, mostly composed of novel sequences. We detect several metagenomic assembled bacterial genomes at strain level resolution, and several putative phage-bacteria interactions, evidenced by the recovered viral and bacterial genomic signatures. We postulate that at least one bacterial strain detected could be endogenous to the Canastra region, in Brazil, and that its growth seems to be modulated by native phages present in this artisanal production system. This relationship is likely to influence the fermentation dynamics and ultimately the sensorial profile of these cheeses, with implication for all cheeses that employ similar production processes around the world.

Artisanal cheeses made with raw milk are highly appreciated products in Brazil. Most of these cheeses are produced in small facilities across different production regions in the country, some of which have been granted a protected designation of origin and are award winners. The most prominent state that manufactures these products is Minas Gerais (MG), but production is also gaining strength in other Brazilian states. The major challenge faced by artisanal cheese production is related to microbial risks associated with foodborne pathogens when the quality of the raw milk is unsatisfactory. Regulations created for the dairy industry are constantly been revised and adapted, considering the small-scale production of Brazilian artisanal cheeses, in order to guarantee safety at all steps of cheese production and commercialization. This text presents a summary of the huge diversity of artisanal cheeses produced in the country, grouped by geographical regions, and reviews the current challenges faced by producers and government considering the safety of these cheeses.

INTRODUCTION: Minas fresh cheese (MFC), a Brazilian white cheese, is one of the most popular cheeses nationwide. Studies have shown that Listeria monocytogenes occurrence in this product is generally low, while high populations of coliforms can be found. This study aimed to evaluate the influence of coliforms in the behavior of L. monocytogenes in MFC. METHODS: Pasteurized milk was inoculated with L. monocytogenes and coliforms, and the acidification was made by lactic acid or by the addition of a starter culture. The cheeses of each production were divided into 3 groups and stored at 5 ºC, 12 ºC and cycles of 5 ºC followed by 25 ºC. In predetermined days, samples were taken and L. monocytogenes, coliforms and lactic acid bacteria populations were evaluated, besides the pH, water activity (aw), titratable acidity and NaCl concentration. RESULTS: The inhibition of L. monocytogenes in the presence of coliforms was observed (p < 0.05), except for those samples prepared with lactic acid and stored at temperature cycles. The values of pH and aw were not sufficiently low to cause inhibition; however, titratable acidity was higher in cheeses containing coliforms. In vitro tests containing lactic acid and L. monocytogenes showed that the bacterium is sensitive to concentration of lactic acid ≥ 0.3%, indicating that lactic acid produced by coliforms strongly influences the population of L. monocytogenes. CONCLUSIONS: Thus, it can be concluded that coliforms negatively impact populations of L. monocytogenes in MFC. We strongly recommend that producers of MFC adopt good hygiene practices to not only avoid contamination with L. monocytogenes, but also coliforms. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s42770-021-00431-4.

Background Several actions in the realm of public policies and programs have been implemented worldwide to prevent and control the spread of COVID-19. As Brazil and many parts of the world are marked by regional, cultural, and social inequalities, risk communication and assimilation of protection recommendations by the public may be erratic, hampering the proper measurement of their effectiveness. Scope and approach Even though transmission of SARS-CoV-2 by foods is unlikely, this work aimed to evaluate the population's adherence to the recommended food hygiene and personal protection measures to prevent COVID-19. An online survey containing questions on food hygiene and personal protection was publicly disseminated via internet and social networks. Data from 3000 respondents were collected and discussed herein. Key findings and conclusions: Most respondents adopted the recommended hygienic and personal protection measures to avoid contamination with SARS-CoV-2. However, some important flaws were detected, such as lack of use of face masks when in public places (6%), improper hand washing and sanitizing (10–12%) and use of incorrect products for food or environment cleaning and sanitization (28%), indicating that adequate risk communication and preventive recommendations must continue in order to avoid contamination with the coronavirus. The heighten awareness with food hygiene during the pandemic may have an enduring positive effect on food safety.

Aims This study evaluated the microbiological quality and safety of minimally processed parsley sold in southeastern Brazilian food markets. Methods and results One hundred samples were submitted to the enumeration of Enterobacteriaceae by plating on MacConkey agar. Colonies of Enterobacteriaceae were randomly selected and identified by MALDI-TOF MS. Samples were also tested for Listeria monocytogenes and Salmonella spp. The mean count of Enterobacteriaceae was 6.0±1.0 log CFU g-1 , while 18 genera (including 30 species) of bacteria belonging to this family were identified. Salmonella and L. monocytogenes were not detected, while L. innocua was found in two samples and L. fleischmannii was found in one sample. Moreover, generic Escherichia coli was found in three samples, all from different brands of minimally processed parsley. Conclusions Even though microbial pathogens were not isolated, a variety of indicator microorganisms were identified, including vegetable spoilers and species capable of causing human opportunistic infections. These results suggest hygienic failures and/or lack of temperature control during processing and storage of these ready-to-eat products. Significance and impact of study This study highlights the need for control measures during the production chain of minimally processed parsley in order to reduce microbial contamination and the risks of foodborne diseases.

Chromobacterium violaceum is a Gram-negative, saprophytic bacterium that can infect humans and its virulence may be regulated by quorum sensing via N-acyl homoserine lactones. A virtual screening study with plant compounds and nonsteroidal anti-inflammatory drugs for inhibition of C. violaceum quorum sensing system has been performed. In vitro evaluation was done to validate the in silico results. Molecular docking showed that phytol, margaric acid, palmitic acid, dipyrone, ketoprofen, and phenylbutazone bound to structures of CviR proteins of different C. violaceum strains. Phytol presented higher binding affinities than AHLs and furanones, recognized inducers, and inhibitors of quorum sensing, respectively. When tested in vitro, phytol at a non-inhibitory concentration was the most efficient tested compound to reduce phenotypes regulated by quorum sensing. The results indicate that in silico compound prospection to inhibit quorum sensing may be a good tool for finding alternative lead molecules.

Artisanal cheeses made with raw milk are highly appreciated products in Brazil. Most of these cheeses are produced in small properties across different production regions in the country, many of which have been granted a protected designation of origin. The most prominent state that manufactures these products is Minas Gerais, but production is also gaining strength in other Brazilian states. This text presents an overview of the many types of artisanal cheeses produced in the country, grouped by geographical regions, and reviews the current challenges faced by producers and government considering the safety of these cheeses.

Acyl-homoserine lactones (AHLs) are quorum sensing (QS) signaling molecules that mediate cell-to-cell communication in Gram-negative bacteria. Salmonella does not produce AHL, however, it can recognize AHLs produced by other species through SdiA protein modulating important cellular functions. In this work, the influence of the N-dodecanoyl-DL-homoserine lactone (C12-HSL) on glucose consumption, metabolic profile, and gene expression of Salmonella throughout the cultivation time in Tryptic Soy Broth (TSB) under anaerobic conditions was evaluated. Analysis of the supernatant culture in high-performance liquid chromatography (HPLC) revealed lower glucose uptake after 4 and 6 h of the addition of C12-HSL. Gas chromatography-mass spectrometry (GC-MS) based analysis of the intracellular metabolites revealed C12-HSL perturbation in the abundance levels of metabolites related to the metabolic pathways of glycerolipids, purines, amino acids, and aminoacyl-tRNA biosynthesis. The real-time quantitative PCR (RT-qPCR) indicated that Salmonella increase expression of genes associated with nucleoside degradation and quantification of metabolites supported the induction of pentose phosphate pathway to ensure growth under lower glucose consumption. The obtained data suggest an important role of C12-HSL in the optimization of metabolism at a situation of high population densities.

Food Microbiology is included in majors such as Food Engineering, Food Science and Technology, Nutrition, Veterinary Medicine, Gastronomy, Pharmaceutical Sciences, among others. Food safety and hygiene are usually the focus, but the technological applications of microbes through fermentations are also covered. During an education symposium at the Brazilian Congress of Microbiology in 2017, a group of professors expressed their difficulties associated with teaching to new generations, the use of technology in the classroom, and the application of new learning tools. The objective of this study was to gather information about the educational practices among Brazilian professors who teach Food Microbiology throughout the country. The results indeed confirmed the diversity of careers in which food microbiology is taught. We verified that professors mixed traditional teaching strategies with modern active learning methods, even though some difficulties associated with lack of time, pedagogical training, and low adherence of students for adopting these modern methods were commonly highlighted. The preferred teaching approaches were dialogued or discussed lectures, seminars, homework, case studies, and field visits. It is noteworthy that most professors still use traditional teaching methods. It is crucial that awareness concerning the educational needs in different careers and the challenges and dilemmas facing education for the new generations should be dealt with by using effective teaching approaches in food microbiology education. We suggest that a more permanent discussion forum among faculty members dealing with food microbiology in the country should be launched and this work is a step towards this goal. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s42770-019-00107-0) contains supplementary material, which is available to authorized users.

Cocoa fermentation is a spontaneous process shaped by a variable microbial ecosystem which is assembled due to cross-feeding relationship among yeasts and bacteria, resulting in a synchronized microbial succession started by yeasts, followed by lactic acid bacteria (LAB) and finalized by acetic acid bacteria (AAB). Several studies have indicated the effect of microbial interactions in food ecosystems highlighting the importance of quorum sensing (QS) in bacterial adaptation in harsh environments modulating several phenotypes such as biofilm formation, tolerance to acid stress, bacteriocin production, competence, morphological modifications, motility, among others. However, antagonic interactions also occur, and can be marked by Quorum Quenching (QQ) activity, negatively impacting QS regulated phenotypes. Our current knowledge regarding microbial cocoa composition and functioning is based on culture-based analysis and culture-independent PCR-based methods. Therefore, we set out to investigate the application of metagenomics analysis on a classical spontaneous cocoa fermentation in order to describe: (I) the microbial taxonomic composition; (II) the functional potential of the cocoa microbiome; (III) the microbiome putative QS potential; and (IV) the microbiome QQ potential. Both aims III and IV are related to the expression of effectors that may confer advantageous traits along fermentation which can explain their dominance in specific time zones during the entire process. We have observed a bacterial succession shaped by yeasts and filamentous fungi and then Enterobacteriaceales, LAB and AAB, as well as a diverse genetic metabolic potential related to proteins and carbohydrates metabolism associated to the yeast Saccharomyces cerevisiae and members of the Enterobacteriaceales order and LAB and AAB groups. In addition, in silico evidences of interspecific QS arsenal were found in members of the genera Enterobacter, Lactobacillus, Bacillus and Pantoea, while inferences of intraspecific QS potential were found in the members of the genera Bacillus, Enterobacter, Komagataeibacter, Lactobacillus and Pantoea. In addition, a QQ potential was detected in Lactobacillus and in AAB members. These findings indicate that QS and QQ may modulate bacterial dominance in different time points during fermentation, along with cross-feeding, being responsible for their maintenance in a large time range.

There is great interest in developing alternatives to improve food safety, since food-borne diseases (FBD) are a major public health concern worldwide. Plant extracts have the potential to inhibit microbial growth due to the action of secondary metabolites, such as phenolic compounds. This study evaluated the antioxidant and antimicrobial activities of phenolic compounds extracted from grumixama (Eugenia brasiliensis) and pitanga (Eugenia uniflora) fruits and the antimicrobial potential of extract of grumixama upon incorporation into cellulosic films. Both fruits were rich in total phenolic compounds and their extracts showed antioxidant activity. The crude and phenolic extracts of grumixama showed higher activity than those isolated from pitanga. All extracts inhibited the growth of Staphylococcus aureus. After incorporation into cellulosic films, the crude extract of grumixama remained active, reducing the S. aureus population in 4 log cycles. The cellulosic films incorporated with grumixama extract were stable after seven days of storage under refrigeration at 7º C; but they partially lost antimicrobial activity when exposed to UV radiation. These phenolic compound-containing cellulosic films could be used as a complementary preservation method of foods that are prone to contamination with S. aureus. Existe un gran interés en desarrollar alternativas para mejorar la seguridad alimentaria, ya que las enfermedades transmitidas por los alimentos son un importante problema de salud pública a nivel mundial. Los extractos de plantas tienen el potencial de inhibir el crecimiento microbiano debido a la acción de metabolitos secundarios, como los compuestos fenólicos. Este estudio evaluó las actividades antioxidantes y antimicrobianas de compuestos fenólicos extraídos de frutos de grumixama (Eugenia brasiliensis) y pitanga (Eugenia uniflora) y el potencial antimicrobiano del extracto de grumixama tras su incorporación a películas celulósicas. Ambas frutas eran ricas en compuestos fenólicos totales y sus extractos mostraron actividad antioxidante. Los extractos crudos y fenólicos de grumixama mostraron mayor actividad que los extractos de pitanga. Todos los extractos inhibieron el crecimiento de Staphylococcus aureus. Después de su incorporación a películas celulósicas, el extracto crudo de grumixama permaneció activo, reduciendo la población de S. aureus en 4 ciclos logarítmicos. Las películas celulósicas incorporadas con extracto de grumixama se mantuvieron estables tras siete días de almacenamiento en refrigeración a 7ºC; pero perdieron parcialmente la actividad antimicrobiana cuando se expusieron a la radiación UV. Estas películas celulósicas que contienen compuestos fenólicos podrían usarse como un método de conservación complementario de alimentos que son propensos a contaminarse con S. aureus. Existe um grande interesse em desenvolver alternativas para melhorar a segurança dos alimentos, uma vez que as doenças transmitidas por alimentos representam um grande problema de saúde pública em todo o mundo. Os extratos vegetais possuem potencial de inibição do crescimento microbiano devido à ação de metabólitos secundários, como os compostos fenólicos. Dessa forma, o presente estudo avaliou as atividades antioxidante e antimicrobiana de compostos fenólicos extraídos de grumixama (Eugenia brasiliensis) e pitanga (Eugenia uniflora), bem como o potencial antimicrobiano do extrato de grumixama incorporado em filmes celulósicos. Foi demonstrado que ambas as frutas possuem elevado teor de compostos fenólicos totais e seus extratos apresentaram atividade antioxidante. Os extratos bruto e fenólico de grumixama apresentaram maior atividade do que os extratos de pitanga. Todos os extratos inibiram o crescimento de Staphylococcus aureus. Após incorporação aos filmes celulósicos, o extrato bruto de grumixama permaneceu ativo, reduzindo a população de S. aureus em 4 ciclos logarítmicos. Os filmes celulósicos permaneceram estáveis após sete dias de armazenamento sob refrigeração a 7ºC; no entanto, perderam parcialmente a atividade antimicrobiana quando expostos à radiação UV. Conclui-se que esses filmes contendo compostos fenólicos podem ser usados como método complementar de preservação de alimentos propensos à contaminação com S. aureus.

The emergence of bacterial strains resistant to different antibiotics has prompted the search for new sources of antimicrobial compounds. Studies have shown that jambolan [Syzygium cumini (L.) Skeels], a tropical fruit from the Mirtaceae family, contains a great variety of phytochemical compounds with high antioxidant and antimicrobial activity. This study aimed to determine the centesimal composition and physicochemical characteristics of the pulp and seed of S. cumini (L.) Skeels, as well as the content of total phenolic compounds and the antioxidant, antibacterial, antibiofilm and anti-quorum sensing (QS) activities of the phenolic extracts obtained from the pulp and the seeds of this fruit. The in vitro antibacterial and anti-QS activities of active films incorporating phenolic extracts were also evaluated. Additionally, we performed molecular docking of phenolic compounds present in jambolan with the CviR QS regulator of Chromobacterium violaceum. The composition and physicochemical characteristics of the samples presented similar values to those found for the species. However, the seed phenolic extract had a higher content of phenolic compounds and antioxidant activity than the pulp. Both phenolic extracts presented antibacterial activity against Aeromonas hydrophila, C. violaceum, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica serovar Typhimurium, Serratia marcescens, Listeria monocytogenes, and Staphylococcus aureus. The seed phenolic extract was particularly inhibitory against S. aureus. The pulp phenolic extract inhibited swarming motility and biofilm formation of A. hydrophila, E. coli, and S. marcescens in sub-MIC concentrations. The pulp and seed phenolic extracts inhibited violacein production in C. violaceum. Films incorporating both phenolic extracts inhibited the growth of bacteria, particularly Pseudomonas fluorescens, L. monocytogenes, and S. aureus, as well as QS in C. violaceum. Molecular docking showed that a variety of compounds found in pulp and seed extracts of jambolan, particularly chlorogenic acid and dihydroquercetin, potentially bind CviR protein and may interfere with QS. Our results indicate that pulp and seed of jambolan are good sources of antibacterial, antibiofilm, and anti-QS compounds that can be used in the development of natural preservatives and for application in antibacterial active films.

This study aimed to assess the foodborne diseases (FBD) outbreaks reported in Brazil between 2000 and 2018, based on data from the Brazilian Ministry of Health (official data) and from the scientific literature. According to official data, 13,163 FBD outbreaks were reported in the country during this period, involving 247,570 cases and 195 deaths. The largest prevalence of FBD outbreaks was observed in the Southeast region of Brazil (45.6%). In most outbreaks it was not possible to determine the food implicated (45.9%) but among those identified, water was the most frequently associated (12.0%). The etiological agent was not identified in most outbreaks (38.0%), while Salmonella (14.4%) was the most frequently reported, among those identified. Homes were the main site of FBD occurrence (12.5%). Regarding data obtained from the scientific literature, 57 articles dealing with FBD in the country throughout the same period were selected and analyzed. Based on these articles, mixed foods were the most prevalent in the outbreaks (31.6%), Salmonella spp. was the pathogen most frequently reported (22.8%) and homes were also the main site of FBD occurrence (45.6%). Despite under-notification, the records of FBD outbreaks that have occurred in Brazil in the past recent years show alarming data, requiring attention from health authorities. The notification of outbreaks is essential to facilitate public health actions.

Quorum sensing (QS) regulates bacterial gene expression and studies suggest quercetin, a flavonol found in onion, as a QS inhibitor. There are no studies showing the anti-QS activity of plants containing quercetin in its native glycosylated forms. This study aimed to evaluate the antimicrobial and anti-QS potential of organic extracts of onion varieties and its representative phenolic compounds quercetin aglycone and quercetin 3-β-D-glucoside in the QS model bacteria Chromobacterium violaceum ATCC 12472, Pseudomonas aeruginosa PAO1, and Serratia marcescens MG1. Three phenolic extracts were obtained: red onion extract in methanol acidified with 2.5% acetic acid (RO-1), white onion extract in methanol (WO-1) and white onion extract in methanol ammonium (WO-2). Quercetin 4-O-glucoside and quercetin 3,4-O-diglucoside were identified as the predominant compounds in both onion varieties using HPLC-DAD and LC-ESI-MS/MS. However, quercetin aglycone, cyanidin 3-O-glucoside and quercetin glycoside were identified only in RO-1. The three extracts showed minimum inhibitory concentration (MIC) values equal to or above 125 μg/ml of dried extract. Violacein production was significantly reduced by RO-1 and quercetin aglycone, but not by quercetin 3-β-D-glucoside. Motility in P. aeruginosa PAO1 was inhibited by RO-1, while WO-2 inhibited S. marcescens MG1 motility only in high concentration. Quercetin aglycone and quercetin 3-β-D-glucoside were effective at inhibiting motility in P. aeruginosa PAO1 and S. marcescens MG1. Surprisingly, biofilm formation was not affected by any extracts or the quercetins tested at sub-MIC concentrations. In silico studies suggested a better interaction and placement of quercetin aglycone in the structures of the CviR protein of C. violaceum ATCC 12472 than the glycosylated compound which corroborates the better inhibitory effect of the former over violacein production. On the other hand, the two quercetins were well placed in the AHLs binding pockets of the LasR protein of P. aeruginosa PAO1. Overall onion extracts and quercetin presented antimicrobial activity, and interference on QS regulated production of violacein and swarming motility.

Thermal processing of coconut water is designed to ensure safety and stability and microwave may be used as an alternative process. This study evaluated the feasibility of microwave processing of acidified green coconut water (pH 4.30–4.50) concerning inactivation of Bacillus coagulans spores with specific power between 115 and 135 W/mL. Four variables were evaluated (temperature, microwave power, amount, and composition of added acids) according to a central composite design with four replicates at the center point. After holding periods of 5, 10, 15 and 20 min, the reduction in spore population was determined. The only significant variable for spore inactivation was the temperature; consequently, the survival curves were described by Weibull model, which was adjusted in a single-step procedure that integrated the time-temperature profile of 112 experiments. The α value (time of the first decimal reduction) at reference temperature of 90 °C was 33.8 s and the z ′ value (temperature required for a 10-fold change in α ) was 5.06 °C. The reduction in the population of B. coagulans spores and the kinetics parameters suggest that microwave may be used as a viable alternative for coconut water processing.

Canastra cheese is an artisanal product from the Serra da Canastra region in Brazil. It is produced with raw milk and an endogenous culture called pingo. Brazilian legislation requires 22 days of ripening to ensure microbiological safety. This study evaluated the microbiological characteristics of samples collected in two settings. In the first, samples were harvested along the manufacturing process (including milk, pingo, curd and cheese at different ripening times) from three producers registered in the state's quality program. In the second setting, cheese samples were collected from 78 local producers, after ripening. All samples were assessed for total coliforms, Escherichia coli, coagulase positive Staphylococcus and submitted to pH measurement. Enterobacteriaceae, Salmonella spp., and Listeria monocytogenes were tested in cheeses from the second setting, in addition to aw measurement. Results collected during cheese production indicated that the regulatory microbiological limits related to counts of total coliforms, E. coli and Staphylococcus could be reached before 22 days. Conversely, the study with cheeses collected from a larger pool of producers (samples with 22 days of ripening) showed a high number of non-compliances to the Brazilian regulation, regardless of registration in the quality program. Counts of coagulase positive Staphylococcus were above the legal limits in many samples, one was positive for L. monocytogenes, while Salmonella was not detected. The pH and aw were not good indicators of safety, as none of these parameters correlated with microbial counts. There is a need for improvements in the good manufacturing practices in the Canastra cheese production chain.

We describe the characterization of the centesimal composition, mineral and phenolic content of Eugenia uniflora fruit and the determination of the antioxidant, antimicrobial and quorum quenching activities of the pulp phenolic extract. Centesimal composition was determined according to standard methods; trace elements were measured by total reflection X-ray fluorescence spectroscopy. The phenolic compounds were extracted by solid-phase chromatography and quantified by spectrophotometry. Antioxidant activity was determined by using 3 different methods. Antimicrobial activity was evaluated against a panel of foodborne microorganisms and antiquorum sensing activity in Chromobacterium violaceum was performed by measuring inhibition of quorum sensing dependent violacein production. The centesimal composition (per 100 g of pulp) was as follows: protein 3.68 ± 0.21 g, lipids 0.02 ± 0.03 g, carbohydrates 10.31 g and fiber 2.06 g. Trace elements (mg/g of pulp) were determined as: K 0.90, Ca 3.36, Fe 0.60, Zn 0.17, Cl 0.56, Cr 0.06, Ni 0.04, and Cu 0.07. The pulp is a source of phenolic compounds and presents antioxidant activity similar to other berries. The fruit phenolic extract inhibited all tested bacteria. We also found that the fruit phenolic extract at low subinhibitory concentrations inhibited up to 96% of violacein production in C. violaceum, likely due to the fruit's phenolic content. This study shows the contribution of E. uniflora phenolic compounds to the antioxidant, antimicrobial and the newly discovered quorum quenching activity, all of which could be used by the food and pharmaceutical industries to develop new functional products.

Phenolic compounds are plant secondary metabolites that present many biological effects including antioxidant and antimicrobial activities. Studies have shown that these compounds can also inhibit quorum sensing bacterial communication. The aim of this study was to characterize the centesimal composition, mineral and phenolic content, to determine the antioxidant and antimicrobial effect as well as the inhibition of quorum sensing by the phenolic extract obtained from wild strawberry ( Rubus rosaefolius ). Centesimal composition and minerals were in the range expected for fruits of the Rubus generum, even though Fe and Zn presented higher levels. The phenolic content was 5902.89 mg GAE/L, also approaching the levels found for fruits of Rubus sp. The antioxidant activity determined through the ABTS method was 162.4 ± 5.6 and 120.8 ± 1.5 μM Trolox/g of fruit in the DPPH assay, indicating an elevated potential for ABTS and medium potential for DPPH method. The phenolic extract was able to inhibit all the evaluated bacteria presenting MICs in the range of 491.90–1475.74 mg GAE/L. In sub-MIC concentrations, the phenolic extract inhibited all the phenotypes typically regulated by quorum sensing in bacteria, including violacein production, swarming motility and biofilm formation. The phenolic extract of R. rosaefolius presented antioxidant, antimicrobial and anti-quorum sensing activities which are in agreement with previous studies linking phenolic compounds to these properties.

Capsicum peppers have not been investigated as sources of quorum sensing (QS) inhibitors. This study aimed to identify compounds in pimenta-malagueta (Capsicum frutescens) and red pepper (Capsicum annuum) extracts and to evaluate their effect on violacein production in Chromobacterium violaceum ATCC 12472 and C. violaceum CV026, as well as biofilm formation (BF) in Pseudomonas aeruginosa PAO1 and Serratia marcescens MG1. Among the extracts, pimenta-malagueta methanolic extract (PMME) was chosen because it contained capsaicin, dihydrocapsaicin, and luteolin in greater amount than the other extracts. In general, PMME partially inhibited bacterial growth at 2.5 and 5.0 mg/mL, as well as capsaicin at 100 µg/mL and luteolin at 62.5, 125, and 250 µg/mL. At lower concentrations, PMME and luteolin reduced violacein production in C. violaceum ATCC 12472 without affecting growth, a result that was not observed with capsaicin. We show that violacein inhibition by PMME is likely due to luteolin. In silico docking evaluation showed that luteolin binds to the CviR QS regulator. Crystal violet staining and confocal microscopy revealed that BF was increased by PMME and capsaicin, being remarkably superior for P. aeruginosa PAO1 at 30 °C. Capsaicin is not an effective QS inhibitor, while luteolin should be further investigated for its potential effects in QS regulated phenotypes. PRACTICAL APPLICATION: Quorum sensing (QS) is a form of bacterial communication targeted for studies aiming to inhibit bacterial virulence. QS regulates phenotypes that influence microbial activities across many areas, including Food Science. Capsicum frutescens is a type of chili pepper consumed in Brazil, rich in bioactive compounds such as capsaicin (which gives its pungency) and luteolin (a phenolic compound). We show that C. frutescens extract and luteolin inhibit QS in a model bacterium, along with the possible molecular mechanism of inhibition. Capsaicin did not inhibit QS neither biofilm formation. Luteolin should be further investigated for its QS inhibition properties and biotechnological applications.

Salmonella belongs to the Enterobacteriaceae family which is widely distributed in the environment due to its adaptive capacity to stress conditions. In addition, Salmonella is able to perform a type of cell-to-cell communication called quorum sensing, which leads to differential gene expression. The quorum sensing system mediated by AI-1, acyl homoserine lactones (AHLs), is incomplete in Salmonella because the luxI homolog gene, which encodes for AI-1 synthase, is missing in the genome. However, a homologue of LuxR, known as SdiA, is present and allows the detection of signaling molecules produced by other species of bacteria, leading to regulation of gene expression, mainly related to virulence and biofilm formation. Thus, in view of the importance of quorum sensing on the physiology regulation of microorganisms, the aim of the present study was to perform a virtual screening of plant compounds and nonsteroidal anti-inflammatory drugs (NASIDs) for inhibition of quorum sensing by molecular docking and biofilm formation in Salmonella. In general, most plant compounds and all NSAIDs bound in, at least, one of the three modeled structures of SdiA proteins of Salmonella Enteritidis PT4 578. In addition, many tested compounds had higher binding affinities than the AHLs and the furanones which are inducers and inhibitors of quorum sensing, respectively. The Z-phytol and lonazolac molecules were good candidates for the in vitro inhibition tests of quorum sensing mediated by AI-1 and biofilm formation in Salmonella. Thus, this study directs future prospecting of plant extracts for inhibition of quorum sensing mechanism depending on AHL and biofilm formation. In addition, the use of inhibitors of quorum sensing and biofilm formation can be combined with antibiotics for better treatment efficacy, as well as the use of these compounds to design new drugs.

Quorum sensing is a cell-cell communication mechanism mediated by chemical signals that leads to differential gene expression in response to high population density. Salmonella is unable to synthesize the autoinducer-1 (AI-1), N-acyl homoserine lactone (AHL), but is able to recognize AHLs produced by other microorganisms through SdiA protein. This study aimed to evaluate the fatty acid and protein profiles of Salmonella enterica serovar Enteritidis PT4 578 throughout time of cultivation in the presence of AHL. The presence of N-dodecanoyl-homoserine lactone (C12-HSL) altered the fatty acid and protein profiles of Salmonella cultivated during 4, 6, 7, 12 and 36 h in anaerobic condition. The profiles of Salmonella Enteritidis at logarithmic phase of growth (4 h of cultivation), in the presence of C12-HSL, were similar to those of cells at late stationary phase (36 h). In addition, there was less variation in both protein and fatty acid profiles along growth, suggesting that this quorum sensing signal anticipated a stationary phase response. The presence of C12-HSL increased the abundance of thiol related proteins such as Tpx, Q7CR42, Q8ZP25, YfgD, AhpC, NfsB, YdhD and TrxA, as well as the levels of free cellular thiol after 6 h of cultivation, suggesting that these cells have greater potential to resist oxidative stress. Additionally, the LuxS protein which synthesizes the AI-2 signaling molecule was differentially abundant in the presence of C12-HSL. The NfsB protein had its abundance increased in the presence of C12-HSL at all evaluated times, which is a suggestion that the cells may be susceptible to the action of nitrofurans or that AHLs present some toxicity. Overall, the presence of C12-HSL altered important pathways related to oxidative stress and stationary phase response in Salmonella.

Listeria monocytogenes is a Gram-positive bacterium commonly associated with foodborne diseases. Due its ability to survive under adverse environmental conditions and to form biofilm, this bacterium is a major concern for the food industry, since it can compromise sanitation procedures and increase the risk of post-processing contamination. Little is known about the interaction between L. monocytogenes and Gram-negative bacteria on biofilm formation. Thus, in order to evaluate this interaction, Escherichia coli and L. monocytogenes were tested for their ability to form biofilms together or in monoculture. We also aimed to evaluate the ability of L. monocytogenes 1/2a and its isogenic mutant strain (ΔprfA ΔsigB) to form biofilm in the presence of E. coli. We assessed the importance of the virulence regulators, PrfA and σB, in this process since they are involved in many aspects of L. monocytogenes pathogenicity. Biofilm formation was assessed using stainless steel AISI 304 #4 slides immersed into brain heart infusion broth, reconstituted powder milk and E. coli preconditioned medium at 25 °C. Our results indicated that a higher amount of biofilm was formed by the wild type strain of L. monocytogenes than by its isogenic mutant, indicating that prfA and sigB are important for biofilm development, especially maturation under our experimental conditions. The presence of E. coli or its metabolites in preconditioned medium did not influence biofilm formation by L. monocytogenes. Our results confirm the possibility of concomitant biofilm formation by L. monocytogenes and E. coli, two bacteria of major significance in the food industry.

Bacteria engage on a cell-density dependent communication mechanism known as quorum sensing (QS) in order to regulate important phenotypes, including virulence. QS inhibition through the use of small interfering molecules has become attractive as an anti-virulence strategy. There is great potential presented by plant secondary metabolites due to multiple interactions between plants and microbes. The broad classes of phenolic compounds are valuable resources since their interference with QS has been suggested. This chapter will present studies dealing with plant compounds that can interfere with QS and how this interaction happens at the molecular level. We also discuss those compounds or plant extracts in which QS interference has been suggested based upon inhibition of QS controlled phenotypes, even though details about the mechanism of action are still missing. Quorum sensing inhibition has emerged as an antivirulence strategy and phytochemicals are among the main compounds that can be used in biotechnological applications directed to the food and pharmaceutical industries.

International audience; Salmonella enterica enters a viable but nonculturable (VBNC) state in adverse environmental conditions. Under nutritional stress, RelA and SpoT proteins synthesize (p) ppGpp, a molecule that controls the expression of genes important for the survival of a cell under those conditions. This study aimed to verify the involvement of (p) ppGpp in the entry of S. enterica serovar Enteritidis PT4 578 cells into the VBNC state by evaluating Delta relA and Delta relA Delta spoT mutants. The wild-type and mutant strains deficient in (p) ppGpp synthesis were subjected to osmotic, nutritional and cold stress, after which the cells entered a VBNC state at different time periods, concurrent with reductions in cell diameter, volume and length, and conversion from a bacillary to a coccoid form. No difference in the culturability or cell viability of the wild-type and single and double mutants was observed. Expression of the rpoS gene was increased in the double mutant, while both mutant strains presented a reduction in mreB gene expression after 25 days under conditions of nutritional and cold stress. Surprisingly, (p) ppGpp was not necessary for induction of the VBNC state in Salmonella PT4 578 cells, but may be associated with regulation of genes that control septum formation during cell division, maintaining the bacillary cell morphology (mreB) and stress response (rpoS). Our findings contribute to the understanding of the mechanisms of resistance and survival of Salmonella under adverse conditions.

A água de coco é muito popular em todo o mundo, principalmente em virtude das suas características sensoriais agradáveis, do valor nutricional e das baixas calorias. No entanto, a água de coco é um produto altamente perecível em função da presença de enzimas – tais como peroxidase e polifenoloxidase, que causam alterações indesejáveis na cor – e também em função da sua susceptibilidade à deterioração microbiana. O uso de aditivos químicos tem sido adotado pela indústria com a intenção de aumentar a vida de prateleira do produto. Neste estudo, a eficiência dos conservantes sorbato de potássio e metabissulfito de sódio foi avaliada considerando-se a estabilidade da água de coco carbonatada por meio do delineamento composto central rotacional (DCCR), variando as concentrações de sorbato de potássio entre 0 e 500 mg.L–1, e de metabissulfito de sódio entre 0 e 100 mg.L–1. Foram realizadas avaliações físico-químicas de volume de carbonatação, pH, sólidos solúveis totais, oxigênio e dióxido de carbono dissolvidos, acidez, ácido ascórbico, atividade de polifenoloxidase e peroxidase, cor e atributos de turbidez. As análises microbiológicas realizadas foram de contagem total de aeróbios, bem como de enumeração de bolores e leveduras. Observou-se que as concentrações de 375 mg.L–1 de sorbato de potássio e 75 mg.L–1 de metabissulfito de sódio apresentaram os melhores atributos de qualidade, no que diz respeito a pequenas alterações na acidez e à cor da água de coco, desde que a matéria-prima apresentasse contaminação microbiológica baixa. Coconut water is popular worldwide, mainly because of its pleasant sensory characteristics, nutritional value and low calorie density. However, coconut water is a highly perishable product due to the presence of enzymes such as peroxidase and polyphenoloxidase, which cause undesirable changes in colour, and also because of its susceptibility to microbial spoilage. The use of chemical additives has been adopted by the industry with the intent of increasing product shelf life. In this study, the efficiency of the preservatives potassium sorbate and sodium metabisulphite was assessed using a Central Composite Rotational Design (CCRD) to determine the stability of carbonated coconut water, varying the concentrations of potassium sorbate from 0 to 500 mg.L–1, and of sodium metabisulphite from 0 to 100 mg.L–1. The chemical evaluations included carbonation volume, pH, soluble solids, dissolved oxygen and carbon dioxide, acidity, ascorbic acid, polyphenoloxidase and peroxidase activities, colour and turbidity attributes. The microbiological evaluations considered the total aerobic plate count and the enumeration of yeasts and moulds. It was observed that concentrations of 375 mg.L–1 of potassium sorbate and 75 mg.L–1 of sodium metabisulphite gave the best quality attributes with respect to minor changes in acidity and colour of the coconut water, providing that the raw material had low microbiological contamination.