Chemical characterization and antibacterial activities of Brazilian propolis extracts from Apis mellifera bees and stingless bees (Meliponini).

The aim of this study was to evaluate the physicochemical composition and antibacterial activity of Brazilian propolis extracts from different types, concentrations, and extraction solvents and from different regions in Brazil. A total of 21 samples were analyzed, comprising 14 samples from Apis mellifera (12 green, 1 brown, and 1 red) and 7 samples from stingless bees (3 mandaçaia, 2 jataí, 1 hebora, and 1 tubuna). The analyses performed were dry extract, total phenolic content (TPC) and antioxidant activity (DPPH and ABTS). The antibacterial activity was performed by Determination of Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC). The results showed that very low levels of phenolic compounds and antioxidant activity decreased the antimicrobial activity of the propolis extracts from tubuna and jataí. However, there was no correlation between the increase in propolis concentration in the extract, and the increase in antimicrobial activity. The highest TPC and antioxidant activity was obtained for green propolis extract made with 70% raw propolis that presented similar antibacterial activity to the samples formulated with 30% or less raw propolis. The aqueous propolis extract showed lower antimicrobial activity compared to the alcoholic extracts, indicating that ethanol is a better solvent for extracting the active compounds from propolis. It was observed that the MIC (0.06 to 0.2 mg/mL) and MBC (0.2 to 0.5 mg/mL) values for Gram-negative bacteria were higher compared to Gram-positive bacteria (MIC 0.001-0.2 mg/mL, and the MBC 0.02-0.5 mg/mL). The propolis extracts that exhibited the highest antimicrobial activities were from stingless bees hebora from the Distrito Federal (DF) and mandaçaia from Santa Catarina, showing comparable efficacy to samples 5, 6, and 7, which were the green propolis from the DF. Hence, these products can be considered an excellent source of bioactive compounds with the potential for utilization in both the pharmaceutical and food industries.

Characterization and Determination of the Antibacterial Activity of Baccharis dracunculifolia Essential-Oil Nanoemulsions.

The aim of this study was to evaluate the antibacterial activity of nanoemulsions of Baccharis dracunculifolia essential oil. The volatile compounds of the essential oil were identified using gas chromatography-mass spectrometry. The properties of the nanoemulsions (droplet size, polydispersity index, pH, and electrical conductivity) were determined. The antibacterial activities of the essential oil and its nanoemulsions were evaluated using MIC, MBC, and disk diffusion. The microorganisms used were: Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 14579, Streptococcus mutans ATCC 25175, and Enterococcus faecalis ATCC 29212) and Gram-negative bacteria (Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC BAA-1706, Salmonella enterica ATCC 14028, and Escherichia coli ATCC 25922). The major volatile compounds of the B. dracunculifolia essential oil were limonene (19.36%), (E)-nerolidol (12.75%), bicyclogermacrene (10.76%), and ß-pinene (9.60%). The nanoemulsions had a mean droplet size between 13.14 and 56.84 nm. The nanoemulsions presented lower and statistically significant MIC values compared to the essential oil, indicating enhancement of the bacteriostatic action. The disk diffusion method showed that both the nanoemulsions and the essential oil presented inhibition zones only for Gram-positive bacteria, while there were no results against Gram-negative bacteria, indicating that B. dracunculifolia essential oil has a better antimicrobial effect on Gram-positive microorganisms.

Prevalence and Antimicrobial Resistance of Salmonella spp. Isolated From Chilled Chicken Meat Commercialized at Retail in Federal District, Brazil.

Salmonella represents one of the most common foodborne pathogens, frequently associated with the contamination of poultry products, constituting a prominent worldwide public health concern. This study determined the prevalence and antimicrobial resistance of Salmonella spp. in chilled chicken meat (115 samples) commercialized at retail in the Federal District, Brazil. Microbiological tests were performed to screen for Salmonella spp. in the chicken meat samples, and the isolated strains were confirmed by the invA gene presence (PCR technique). The strains were evaluated for antimicrobial susceptibility by the disk diffusion technique (Kirby-Bauer method) and tested for the presence of the sul2, blaCTX, and tetB antimicrobial resistance genes. The Salmonella spp. prevalence in chilled chicken meat sold at retail in the Federal District, Brazil, was 46.1% (53 of 115 chicken meat samples analyzed had invA gene-positive strains). Seventy-eight strains of Salmonella spp. isolated from the 53 contaminated samples showed higher resistance to amoxicillin/clavulanic acid (83.3%), followed by sulfonamide (64.1%) and tetracycline (46.2%); 53.8% of the isolates were multidrug-resistant (MDR). The sul2 gene that confers resistance to sulfonamide was found in 53 strains (68.0%), the blaCTX gene that confers resistance to beta-lactams was identified in 39 strains (50.0%), and the tetB gene that confers resistance to tetracycline was identified in 29 strains (37.2%). The high percentage of Salmonella contamination in chicken meat can pose a risk to consumers' health due to the possibility of causing salmonellosis. In addition, many isolates were MDR and carried antimicrobial resistance genes. Public agencies can use these results to develop effective public health policies and strategies to ensure the safety of these food products.

Presence of Tetracycline and Sulfonamide Resistance Genes in Salmonella spp.: Literature Review.

Tetracyclines and sulfonamides are broad-spectrum antibacterial agents which have been used to treat bacterial infections for over half a century. The widespread use of tetracyclines and sulfonamides led to the emergence of resistance in a diverse group of bacteria. This resistance can be studied by searching for resistance genes present in the bacteria responsible for different resistance mechanisms. Salmonella is one of the leading bacteria causing foodborne diseases worldwide, and its resistance to tetracyclines and sulfonamides has been widely reported. The literature review searched the Virtual Health Library for articles with specific data in the studied samples: the resistance genes found, the primers used in PCR, and the thermocycler conditions. The results revealed that Salmonella presented high rates of resistance to tetracycline and sulfonamide, and the most frequent samples used to isolate Salmonella were poultry and pork. The tetracycline resistance genes most frequently detected from Salmonella spp. were tetA followed by tetB. The gene sul1 followed by sul2 were the most frequently sulfonamide resistance genes present in Salmonella. These genes are associated with plasmids, transposons, or both, and are often conjugative, highlighting the transference potential of these genes to other bacteria, environments, animals, and humans.

Prevalence and Antimicrobial Resistance of Salmonella spp. in Aquacultured Nile Tilapia (Oreochromis niloticus) Commercialized in Federal District, Brazil.

This study aimed to assess Salmonella spp. prevalence in aquaculture Nile tilapia commercialized in the Federal District, Brazil, and determine the antimicrobial resistance profile of the isolates. Fifty-seven Salmonella spp. strains were isolated from 101 samples of fresh tilapia fillets collected in the Federal District, Brazil. These isolates were subjected to antimicrobial susceptibility testing by the Kirby-Bauer disk diffusion method and analyzed for the presence of blaCTX, tetB, sul2, and floR resistance genes. The Salmonella spp. prevalence in fresh tilapia fillets was 45.5%; that is, 46 of 101 samples were positive for the InvA gene. The antimicrobial resistance profile showed high resistance rates for amoxicillin/clavulanic acid (87.7%), tetracycline (82.5%), sulfonamide (57.9%), and chloramphenicol (26.3%). Additionally, 56.1% of Salmonella spp. isolates were multidrug-resistant (MDR) isolates. The beta-lactam-resistant gene blaCTX was identified in 66.7% of isolates, the tetracycline resistance gene tetA in 54.4%, and the chloramphenicol resistance gene floR in 50.9%, while the sulfonamide resistance gene sul2 was present in 49.1%. The results revealed that tilapia fillets were highly contaminated with MDR Salmonella. These Salmonella spp. strains carried multiple antimicrobial resistance genes, which might facilitate their dissemination to consumers along the production chain. Hence, there is an evident need to control Salmonella in fish production systems to ensure public health.

Enzymatic hydrolysis of starch into sugars is influenced by microgel assembly.

The use of alginate and chitosan polymer in the immobilization of Aspergillus oryzae ATCC 3940 fungal crude enzyme extract (CEE) amylase was presented. The assembly results change in the application of optimal pH and temperature hydrolysis to convert starch to sugar. Bead arrangement in three microgel supports: the internal support phase (IP), the external support phase (EP), and the internal and external support phase (UP). The best results were obtained using IP and EP. Reusing beads evaluated the stability of immobilized enzymes on IP support, remained active and bound during three cycles of reuse. For free and immobilized (IP) activity showed pH ranged from 5.0 to 7.0; optimum thermal enzymatic greater activity at 45 °C. The method of building the microgel influencing sugar reduction, in a single-step way to immobilize crude fungal amylase extracts can be used in industry.

Avaliação microbiológica de couve minimamente processada comercializada em supermercados de Brasília, DF

No Brasil, a couve minimamente processada é comercializada durante todo o ano e geralmente é considerada segura para o consumo pelos consumidores. Este estudo avaliou a qualidade microbiológica de seis diferentes marcas de couve minimamente processada comercializadas em supermercados de Brasília. As análises realizadas foram: contagem total de bactérias mesófilas e psicrotróficas, determinação de coliformes totais e coliformes termotolerantes e identificação molecular de E. coli,Salmonella spp. e L. monocytogenes por sequenciamento de DNA. Os resultados revelaram que as amostras de couve minimamente processada apresentaram baixa qualidade microbiológica. Coliformes termotolerantes foram encontrados em todas as amostras de couve minimamente processada, com populações superiores a 2 log NMP/g em metade das amostras. Após o sequenciamento de DNA, E. coli O157:H7 foi identificada em 2 das 6 amostras e Salmonella enteritidis foi identificada em 1 das 6 amostras. Listeriamono cytogenes foi encontrada em metade das amostras, sendo que a presença desta bactéria é geralmente associada a um período excessivo de armazenamento ou estocagem em temperaturas abusivas. Estes resultados mostraram que a couve minimamente processada exposta ao consumo nos supermercados de Brasília pode ser um veículo para a transmissão de bactérias patogênicas e indicaram a necessidade de melhorar a qualidade na cadeia de produção dos vegetais minimamente processados para garantir a vida útil e a segurança microbiológica desses produtos.(AU)

In Brazil, minimally processed collard greens is commercialized all year round and generally considered safe to eat by consumers. This study evaluated the microbiological quality of six different brands of minimally processed collard greens commercialized in supermarkets of Brasilia.The analyses carried out were: total counts of mesophilic and psychrotrophic bacteria, determination of total coliforms and thermotolerant coliforms and molecular identification of E. coli O157:H7, Salmonella spp. and L. monocytogenes by DNA sequencing. The results revealed that samples of minimally processed collard greens presented poor microbiological quality. Thermotolerant coliforms were found in all samples of minimally processed collard greens,with populations higher than 2 log MPN.g-1 in in 50% of samples. After DNA sequencing, E. coli O157:H7 was identified in 2 of the 6 samples and Salmonella enteritidis was identified in 1 of 6 samples. Listeria monocytogenes was found in 50%of the samples and the presence of this bacterium is usually associated with an excessive period of storage or storage in abusive temperatures.These results showed that the minimally processed collard greens exposed to consumption in supermarkets of Brasilia may be a vehicle for the transmission of foodborne pathogens and indicated the need of implementing quality programs in the production chain of minimally processed vegetables to improve shelf life and microbiological safety of these products.(AU)

Avaliação microbiológica de couve minimamente processada comercializada nos supermercados de Brasília ­ DF / Microbiological evaluation of minimally processed brassica commercialized in the supermarkets of Brasília - DF

No Brasil, a couve minimamente processada é comercializada durante todo o ano e geralmente é considerada segura para o consumo pelos consumidores. Este estudo avaliou a qualidade microbiológica de seis diferentes marcas de couve minimamente processada comercializadas em supermercados de Brasília. As análises realizadas foram: contagem total de bactérias mesófilas e psicrotróficas, determinação de coliformes totais e coliformes termotolerantes e identificação molecular de E. coli, Salmonella spp. e L. monocytogenes por sequenciamento de DNA. Os resultados revelaram que as amostras de couve minimamente processada apresentaram baixa qualidade microbiológica. Coliformes termotolerantes foram encontrados em todas as amostras de couve minimamente processada, com populações superiores a 2 log NMP/g em metade das amostras. Após o sequenciamento de DNA, E. coli O157:H7 foi identificada em 2 das 6 amostras e Salmonella enteritidis foi identificada em 1 das 6 amostras. Listeria monocytogenes foi encontrada em metade das amostras, sendo que a presença desta bactéria é geralmente associada a um período excessivo de armazenamento ou estocagem em temperaturas abusivas. Estes resultados mostraram que a couve minimamente processada exposta ao consumo nos supermercados de Brasília pode ser um veículo para a transmissão de bactérias patogênicas e indicaram a necessidade de melhorar a qualidade na cadeia de produção dos vegetais minimamente processados para garantir a vida útil e a segurança microbiológica desses produtos.(AU)

Glucosyltransferase production by Klebsiella sp. K18 and conversion of sucrose to palatinose using immobilized cells / Produção de glicosiltransferase por Klebsiella sp. K18 e conversão de sacarose em palatinose utilizando células imobilizadas

The strain Klebsiella sp. K18 produces the enzyme glucosyltransferase and catalyses the conversion of sucrose to palatinose, an alternative sugar that presents low cariogenicity. Response Surface Methodology was successfully employed to determine the optimal concentration of culture medium components. Maximum glucosyltransferase production (21.78 U mL-1) was achieved using the optimized medium composed by sugar cane molasses (80 g L-1), bacteriological peptone (7 g L-1) and yeast extract (20 g L-1), after 8 hours of fermentation at 28ºC. The conversion of sucrose to palatinose was studied utilizing immobilized cells in calcium alginate. The effects of the alginate concentration (2-4%), cell mass concentration (20-40%) and substrate concentration (25-45%) were evaluated and the yield of palatinose was approximately 62.5%.

A linhagem Klebsiella sp. K18 produz a enzima glicosiltransferase que catalisa a conversão de sacarose em palatinose, um açúcar alternativo que apresenta baixa cariogenicidade. Metodologia de Superfície de Resposta foi empregada com sucesso para determinar a concentração ótima dos componentes do meio de cultivo. A máxima produção deglicosiltransferase (21,78 U mL-1) foi obtida utilizando o meio de cultivo otimizado composto por melaço de cana de açúcar (80 g L-1), peptona bacteriológica (7 g L-1) e extrato de levedura (20 g L-1), após 8 horas de fermentação a 28ºC. A conversão desacarose em palatinose foi estudada utilizando células imobilizadas em alginato de cálcio. Os efeitos da concentração de alginato (2-4%), concentração de massa celular (20-40%) e concentração de substrato (25-45%) foram avaliados e a porcentagem de palatinose foi de aproximadamente 62,5%.

Glucosyltransferase production by Klebsiella sp. K18 and conversion of sucrose to palatinose using immobilized cells.

The strain Klebsiella sp. K18 produces the enzyme glucosyltransferase and catalyses the conversion of sucrose to palatinose, an alternative sugar that presents low cariogenicity. Response Surface Methodology was successfully employed to determine the optimal concentration of culture medium components. Maximum glucosyltransferase production (21.78 U mL(-1)) was achieved using the optimized medium composed by sugar cane molasses (80 g L(-1)), bacteriological peptone (7 g L(-1)) and yeast extract (20 g L(-1)), after 8 hours of fermentation at 28°C. The conversion of sucrose to palatinose was studied utilizing immobilized cells in calcium alginate. The effects of the alginate concentration (2-4%), cell mass concentration (20-40%) and substrate concentration (25-45%) were evaluated and the yield of palatinose was approximately 62.5%.

Glucosyltransferase production by Klebsiella sp. K18 and conversion of sucrose to palatinose using immobilized cells

The strain Klebsiella sp. K18 produces the enzyme glucosyltransferase and catalyses the conversion of sucrose to palatinose, an alternative sugar that presents low cariogenicity. Response Surface Methodology was successfully employed to determine the optimal concentration of culture medium components. Maximum glucosyltransferase production (21.78 U mL-1) was achieved using the optimized medium composed by sugar cane molasses (80 g L-1), bacteriological peptone (7 g L-1) and yeast extract (20 g L-1), after 8 hours of fermentation at 28°C. The conversion of sucrose to palatinose was studied utilizing immobilized cells in calcium alginate. The effects of the alginate concentration (2-4%), cell mass concentration (20-40%) and substrate concentration (25-45%) were evaluated and the yield of palatinose was approximately 62.5%.

A linhagem Klebsiella sp. K18 produz a enzima glicosiltransferase que catalisa a conversão de sacarose em palatinose, um açúcar alternativo que apresenta baixa cariogenicidade. Metodologia de Superfície de Resposta foi empregada com sucesso para determinar a concentração ótima dos componentes do meio de cultivo. A máxima produção de glicosiltransferase (21,78 U mL-1) foi obtida utilizando o meio de cultivo otimizado composto por melaço de cana de açúcar (80 g L-1), peptona bacteriológica (7 g L-1) e extrato de levedura (20 g L-1), após 8 horas de fermentação a 28°C. A conversão de sacarose em palatinose foi estudada utilizando células imobilizadas em alginato de cálcio. Os efeitos da concentração de alginato (2-4%), concentração de massa celular (20-40%) e concentração de substrato (25-45%) foram avaliados e a porcentagem de palatinose foi de aproximadamente 62,5%.

Características estructurales de la aorta de conejo oryctolagus cuniculus / Structural features of the aorta of rabbit oryctolagus cuniculus

La estructura microscópica de la aorta de conejo fue estudiada, con recursos de microscopías óptica, electrónica de barrido y de transmisión, en las porciones ascendente torácica y abdominal, observándose variaciones morfométricas en el diámetro vascular y espesor de las capas de la pared aórtica. Los valores obtenidos fueron, generalmente, mayores en la porción ascendente. Características estructurales de la pared vascular fueron descritas, destacándose la presencia de pliegues en la túnica íntima; la formación de conexiones mioelásticas en la túnica media, variaba el número de lamelas elásticas en distintos segmentos, siendo mayor en las porciones torácicas ascendente y descendente, en relación a la porción abdominal. En la túnica adventicia predominaban las fibras del conjuntivo, dispuestas de forma variada, constituyendo una red. Los resultados fueron discutidos en términos morfofuncionales, teniendo presentes las pequeñas, pero significativas, variaciones segmentares observadas en la estructura de la pared aórtica de conejo