Eliezer Avila Gandra

Identification of Staphylococcus aureus, S. intermedius and S. hyicus by PCR amplification of coa and nuc genes

Sixty-five strains of coagulase positive staphylococci (Staphylococcus aureus, S. intermedius and S. hyicus) were identified at species level by PCR amplification of the coa gene, specific for S. aureus, and of the nuc gene, specific for S. intermedius and for S. hyicus.

Listeria spp. no processamento de lingüiça frescal em frigoríficos de Pelotas, RS, Brasil

Food that is highly manipulated, such as fresh sausages, is frequently responsible for spreading food borne diseases. Due to the threat that the bacterium Listeria monocytogenes represents to public health, the aim of this work was to study the presence of Listeria spp., especially Listeria monocytogenes, during processing of fresh sausages, in three slaughterhouses with state food inspection, in the city of Pelotas, Brazil. The raw material used for the sausage elaboration, the equipment used in the processing and the end products were analyzed. The results showed Listeria spp. in 100% of the 41 samples analyzed. Among the different species, L. innocua was the most frequent, isolated from 97.6% of the samples, followed by the L. monocytogenes and L. welshimeri that were isolated from 29.3% and 24.4% of the samples, respectively. The presence of these microorganisms in the samples analyzed, especially in the end product, shows the need for adequateness of the cleaning and sanitation practices of the food processing plants analyzed. It also shows a potential risk of listeriosis to the consumer.

Influence of cutting and deboning operations on the microbiological quality and shelf life of buffalo meat

Considering the specific biochemical composition of buffalo (Bubalus bubalis) meat (high iron content, high biological value proteins and essential fatty acids, low amounts of fat and cholesterol), we evaluated the influence of cutting and deboning operations on the microbiological quality and shelf-life of vacuum-packed buffalo meat stored under refrigeration. On the processing day, samples were collected from carcass, deboning room surfaces and meat cuts. Samples from meat cuts were evaluated weekly for two months. On the processing day, higher counts of Pseudomonas spp. were observed in samples from meat cuts compared with the hindquarters and the processing surfaces. For thermotolerant coliform scores, the averages were -0.5 log MPN·cm(-2), -0.4 log MPN·cm(-2) and 0.9 log MPN·g(-1), respectively. Higher counts of Pseudomonas spp. and LAB in meat cuts were observed on the processing day and after the first week of storage, respectively, remaining constant during shelf life. Listeria grayi was identified in two samples of hindquarters and meat cuts during storage. Listeria innocua was identified in one meat cut. In conclusion, cutting and deboning operations influence the microbiological quality and shelf life of vacuum-packed buffalo meat stored under refrigeration.

Sanitização com produto à Base de Cloro e com Ozônio: Efeito Sobre Compostos Bioativos de Amora-preta (rubus fruticosus) cv. Tupy

O objetivo deste trabalho foi avaliar e comparar a eficiencia da sanitizacao de amora-preta, com diferentes concentracoes e tempos de imersao em hipoclorito de sodio e com ozonio, e avaliar a influencia do processo sobre os compostos bioativos do produto. Foram feitas analises microbiologicas e a determinacao dos compostos bioativos. Os compostos de cloro utilizados na sanitizacao induziram a perdas significativas dos compostos bioativos (compostos fenolicos, antocianinas, tocoferois, acido ascorbico e carotenoides), presentes na amora-preta, sendo eficientes na sanitizacao contra fungos, quando utilizados na concentracao de 200 ppm e por 15 minutos de imersao. Ja os frutos sanitizados com ozonio apresentaram adequacao aos padroes microbiologicos (fungos, coliformes totais e termotolerantes, Escherichia coli e Salmonella spp) estabelecidos pela legislacao, e nao apresentaram alteracoes significativas no conteudo dos compostos bioativos, sendo que a menor concentracao de ozonio presente neste estudo apresentou maior eficacia na sanitizacao dos frutos, comparada com as solucoes de cloro utilizadas.

Evaluation of the (haem)Fe--Nepsilon(2)(HisF8) bond distances from haemoglobin structures deposited in the Protein Data Bank.

Scientists working on the structure and function of proteins use haemoglobin as a model of allosteric proteins. In this molecule, the (haem)Fe-N(2)(His) bond is one of the most significant because the length of this bond provides relevant information about the mechanism of cooperativity and affinity for O(2). Thus, the aim of the present study was to evaluate the quality of the structural models of Hb deposited in the Protein Data Bank (PDB), in particular the reliability of the Fe-N(2) bond distance. To achieve this, 329 Hb structures solved by X-ray diffraction were downloaded from the PDB. The Fe-N(2) bond distance was computed and compared with the ideal value determined using the spectroscopic techniques of X-ray absorption and EXAFS. This investigation showed the presence of crystallographic structures of native haemoglobins deposited in the PDB in which the Fe-N(2) bond distance was far beyond the ideal value found for this length, a fact that makes their use in studies that correlate haemoglobin structure and function questionable.

CONDIÇÕES MICROBIOLÓGICAS DE CALDOS DE CANA COMERCIALIZADOS EM UMUARAMA (PR)

O caldo de cana, tambem conhecido popularmente como garapa, e uma bebida de grande aceitacao pelo consumidor brasileiro, nos vendedores ambulantes normalmente e comercializada sem levar em consideracao conceitos basicos de higiene. Este trabalho teve como objetivo avaliar as condicoes higienico-sanitarias de caldos de cana comercializados na cidade de Umuarama(PR). Para isso, foram realizadas a enumeracao de bacterias mesofilas aerobias, coliformes totais e fecais, bolores e leveduras e Estafilococos coagulase positiva, em 24 amostras de caldos de cana provenientes de estabelecimentos comercializadores destes produtos em Umuarama(PR). Verificaram-se condicoes higienico-sanitarias inadequadas das amostras analisadas, nao sendo estas adequadas para o consumo.

Antimicrobial and antioxidant activity of unencapsulated and encapsulated clove (Syzygium aromaticum, L.) essential oil

Clove (Syzygium aromaticum, L.) essential oil is known for its antimicrobial activity against several pathogenic bacteria. Encapsulation of clove oil was proposed as a mean to disguise its strong odor that limits its uses in food industry. Thus, the aim of this study was extraction, encapsulation and assessment of the antimicrobial and antioxidant potential of clove essential oil. The essential oil showed high DPPH scavenging capacity and low hydroxyl radical inhibition. Clove essential oil showed in vitro inhibitory and bactericidal effect against S. aureus, E. coli, L. monocytogenes and S. Typhimurium. In addition, in situ antimicrobial activity of clove oil against S. aureus was superior to nitrite. The essential oil particles encapsulated with sodium alginate and emulsifiers, showed high encapsulation efficiency, low antioxidant activity and strong antimicrobial inhibition. Similar bacterial growth was observed in meat-like products after addition of either particles or nitrite.

Genetic diversity of Campylobacter jejuni and Campylobacter coli isolated from poultry meat products sold on the retail market in Southern Brazil

ABSTRACT Campylobacter is regarded as the most common bacterial cause of gastroenteritis throughout the world and most cases of human campylobacteriosis can be traced back to the consumption of poultry meat. In Brazil, few studies evaluated the genetic relatedness among Campylobacter isolates. The aim of this research was to evaluate the genetic diversity of Campylobacter spp. isolated from poultry meat products sold on the retail market in Southern Brazil. The presumptive identification of Campylobacter was performed using traditional microbiological analysis, followed by molecular confirmation by PCR. The genetic diversity of isolates was analyzed by pulsed‐field gel electrophoresis (PFGE). Campylobacter spp. was isolated from 91.7% (33/36) of the samples, totaling 48 isolates. Campylobacter jejuni was the most prevalent species isolated (90.8%). PFGE data revealed 26 pulsotypes and 18 PFGE patterns composed of only 1 isolate. Campylobacter isolates exhibited high genetic diversity; however, some clones were recurrent in the poultry meat products sold on the retail market. As the south region of Brazil is an important producer and exporter of chicken meat, our results highlight the need to control this pathogen in the food chain in this area of the world to reduce the risks of exposing consumers to campylobacteriosis.

Biofilm Formation by Coagulase-Positive Staphylococcus aureus Isolated from Mozzarella Cheese Elaborated with Buffalo Milk and its Effect on Sensitivity to Sanitizers

Background: The buffalo milk mozzarella cheese is a new product in the market, with high consumer acceptance and excellent prospects for trade. The cheese is rich in nutrients, which favors the proliferation of microorganisms that can cause food-borne diseases in the consumer. Staphylococcus aureus can cause gastro-enteritis in humans by the production of enterotoxins in food. One problem that may hinder the elimination of undesirable microorganisms in the food industry is the formation of biofilms. The objective of this study was to determine the effect of biofilm formation by Staphylococcus aureus isolated from buffalo mozzarella cheese on sensitivity to sanitizers. Materials, Methods & Results: Fifty samples of buffalo mozzarella cheese were analyzed to investigate the presence of S. aureus. The isolates were obtained through microbiological analysis and identified by PCR. The similarity of the strains was compared through rep-PCR. The distinct strains were tested for biofilm formation in microtiter plates. Soy Tripticase Broth (TSB) was placed in each well of the microtiter plate and overnight cultures of each strain was added. Wells without bacterial culture were used as controls. A villous cap was then placed on the plate and incubated for 48 h at 37°C. During incubation, the biofilms formed on the surface of the villi of the caps. For quantification of biofilm formation, material that remained attached to the cap was stained with crystal violet, the stained biofilm was extracted and the OD570 of each well was measured. Each strain was classified as non-biofilm forming, weak forming, moderately formed or formative strong. Strong forming and non-biofilm forming strains were tested on high density polyethylene, stainless steel and glass surfaces. Plates of 4 cm² of the different materials were placed in TSB where the culture of each isolate was inoculated separately. At each 48 h incubation the plates were washed to remove unbound cells and re-inserted into TSB without the inoculum. After five replicates of the procedure, sterile swabs were passed over the entire surface of each plate for counting in Baird-Parker agar. They were also tested for sensitivity to sodium hypochlorite and iodine after biofilm formation. The biofilm plates were immersed in flasks containing sanitizers, where they remained for 10 min. At the established contact time, the plates were immersed in neutralizing solution for 30 s. After washing with PBS, a sterile swab was passed on the surface of each plate and counts on Baird-Parker agar were performed. The bands profiles obtained on rep-PCR were identical when compared to isolates from the same sample, indicating that each sample was contaminated with only one S. aureus strain. From the twenty S. aureus strain identified, two isolates were classified as strong biofilm formers, seven as moderate formers, ten weak formers and one as non-biofilm builder. The two strong forming strains produced biofilm on the three surfaces tested. The application of sodium hypochlorite and iodine sanitizers promoted a reduction of approximately 2 log bacterial populations on all surfaces of both the biofilm and non-forming strains. Discussion: Most strains of S. aureus isolated from buffalo milk mozzarella cheese have the ability to form biofilm on the surfaces of equipment and utensils that have stainless steel, glass or high density polyethylene components. Although biofilm forming strains are no longer resistant to sanitizers sodium hypochlorite and iodine than non-forming sanitizers, they reach higher concentrations in the biofilm, resulting in larger bacterial populations remaining after application of the sanitizers. These results support the recommendation that the good hygienic practices adopted by industries processing buffalo milk mozzarella cheese should include specific measures to control the Staphylococcus aureus contamination.

Total and Thermo-Tolerant Coliforms, Salmonella spp., Escherichia coli, Pseudomonas spp and Listeria monocytogenes in Broilers Chicken Meat Processing Chain in Southern Brazil

Sixty-six samples were collected from a broiler chicken abattoir. Eighteen samples were collected from the retail market in Southern Brazil, where the slaughtered broilers were commercialized, so that the microbiological assessment of the samples in the broiler industrial chain could be undertaken. And eighteen samples submitted to clients´ common home procedures were similarly assessed. All samples were evaluated by quantifying total and thermotolerant coliforms, psycrotrophic bacteria, Pseudomonas spp, Escherichia coli and research for Salmonella spp and Listeria monocytogenes. Results on counts and on the occurrence of microorganisms in samples from specific sites in the broiler processing chain demonstrate the need for a re-assessment of hygiene practices throughout the whole process and educational activities should be direct to all people involved, including consumers.