Cristina Paiva de Sousa

The impact of food manufacturing practices on food borne diseases

Food-borne illness is a major international problem and an important cause of reduced economic growth. The contamination of the food supply with the pathogens and its persistence, growth, multiplication and/or toxin production has emerged as an important public health concern. Most of these problems could be controlled with the efforts on the part of the food handlers, whether in a processing plant, a restaurant, and others. In contrast with most chemical hazardous compounds, the concentration of food pathogens changes during the processing, storage, and meal preparation, making it difficult to estimate the number of the microorganisms or the concentration of their toxins at the time of ingestion by the consumer. This review shows main microorganisms related to the manipulation practices such as Staphylococcus spp., Escherichia coli and Salmonella spp. and describes the factors regarding the food-borne illness highlighting the impact of good manipulation practices on the food safety and food quality.

Microbiological evaluation of sugarcane juice sold at street stands and juice handling conditions in São Carlos, São Paulo, Brazil

Fresh sugarcane juice is sold by street vendors without any heat treatment in São Carlos, São Paulo, Brazil. Twenty-four samples of point-of-sale juice were tested by standard methods to determine heterotrophic bacteria, total and thermo-tolerant coliform counts, Salmonella, and parasites in the juice. 25% of samples showed poor sanitary conditions, with thermo-tolerant coliform levels higher than allowed by Brazilian standards. Salmonella spp. and parasites were absent in all samples. Thermo-tolerant coliforms were detected on the hands of 37% of juice handlers, and heterotrophic bacterial counts reached 2.0 x 10(3) cfu/per hand. Escherichia coli was detected in one hand sample, and no Salmonella spp. was detected. Screening questionnaires were used to interview the vendors, and 62% of interviewees were either unfamiliar with or failed to adopt adequate hygiene for food handling.

Pathogenicity mechanisms of prokaryotic cells: an evolutionary view.

The success of pathogenic microbes depends on their ability to colonize host tissues and to counter host defense mechanisms. Microorganisms can produce overwhelming infection because of their relatively short generation times, and because they have evolved powerful mechanisms for generating phenotypic diversity as an efficient strategy for adapting to rapidly responding immune system defenses and the broad range of polymorphisms characteristic of different host tissues. Bacterial evolution may not be a continuous process, but more of a succession of temporally spaced major events. These events cause a non-gradual sequence of adaptations to a given environment. The pathogenicity islands may be genetically unstable elements, and many of the genes coding for the adhesins, toxins and other virulence factors are present in pathogenicity islands, which almost certainly had former lives as accessory elements or as parts thereof, or were borne on functional accessory elements. Novel genes are also acquired by transduction (mediated by bacteriophages, plasmids or transposons), by conjugation (DNA transfer between cells) or by transformation (natural DNA uptake). Horizontal gene transfer from other species is a major source of variation and is fundamental to the genetic theory of adaptive evolution in prokaryotes.

Efeitos do processamento térmico e da radiação gama na conservação de caldo de cana puro e adicionado de suco de frutas

Sugarcane juice is a very well-known and popular beverage in Brazil, and provided it is properly exploited, it has a high market potential. The aim of this research was to evaluate the physicochemical, microbiological and sensory stability of pure sugarcane juice and mixed with fresh lemon and pineapple juice, subjected to a heat treatment (70 °C/25 min) and/or gamma radiation (2.5 kGy) and stored in high density polyethylene bottles. The data were evaluated by variance analysis and their mean values compared by Tukeys test. Processing of the sugarcane juice reduced the microorganism load without significantly altering the physicochemical composition, aroma and flavor of the beverages in comparison with the control. Luminosity was higher in the product subjected to the heat treatment combined with gamma radiation than that resulting from the other treatments. The polyphenol oxidase activity in the processed beverages was significantly lower than in the control. The addition of fruit juice to the sugarcane juice did not modify the latters physicochemical composition. However, the addition of 10% pineapple juice to the sugarcane juice increased the manganese and reduced sugars content when compared with pure sugarcane juice and with sugarcane juice mixed with 4% lemon juice.

Antagonistic properties of some microorganisms isolated from Brazilian tropical savannah plants against Staphylococcus coagulase-positive strain

Endophytic microorganisms are relatively unstudied as potential sources of novel natural products for medical and commercial exploitation. The aim of this work was to investigate some Brazilian tropical savannah trees Cassia leptophylla and Prunus spp. in order to isolate the endophytic microorganisms associated with these plants. The samples were disinfected to eliminate the epiphytic population. Colonies were diluted and displayed as drops in media and growing colonies were inactivated. Staphylococcus coagulase-positive strain was used as indicator microorganism and subjected to the antibioses test. Data showed that the microorganisms isolated from Cassia leptophylla had no inhibition against Staphylococcus. On the other hand, microorganisms isolated from Prunus spp. leaves showed antibacterial activity and inhibited Staphylococcus when cultivated in peptone agar as well as in yeast extract agar. Investigation proceeds in order to classify the isolated microorganisms presenting bioactive substance and exploit the potential of the compounds produced to inhibit the indicator bacteria. Other bioactive properties will be investigated.

Endophytic Actinomycetes from Miconia albicans (Sw.) Triana (Melastomataceae ) and Evaluation of Its Antimicrobial Activity

The need for new and useful compounds to provide assistance and relief in all aspects of human condition is over-growing. Seeking to improve the quality of life, the natural products isolated from endophytic microorganisms are important to obtain new compounds that can be used in different

Optimal glucose and inoculum concentrations for production of bioactive molecules by Paenibacillus polymyxa RNC-D

The production of antimicrobial metabolites by Paenibacillus polymyxa RNC-D was assessed. Two process variables, glucose and inoculum concentrations, were evaluated at different levels (5–40 g L−1, and at φr = 2.5–5.0 %, respectively), and their effects on biomass formation, minimal inhibitory concentration (MIC) against Escherichia coli, and surface tension reduction (STR) were studied. When the fermentation process was carried out under non-optimised conditions, the biomass, MIC, and STR achieved the following values: 0.6 g L−1, 1 g L−1, and 18.4 mN m−1, respectively. The optimum glucose (16 g L−1) and inoculum volume ratio (φr = 5.0 %) were defined in order to maximise the biomass formation, with a low value of MIC and high STR of extract. The experiments carried out under optimal conditions showed the following values for the dependent variables: biomass concentration 2.05 g L−1, MIC 31.2 μg mL−1, and STR 10.7 mN m−1, which represented improvement of 241.7 %, 96.9 %, and 41.9 % for the responses of biomass, MIC, and STR, respectively. This is the first recorded study on the optimisation of culture conditions for the production of antimicrobial metabolites of P. polymyxa RNC-D, and constitutes an important step in the development of strategies to modulate the production of antimicrobial molecules by this microorganism at elevated levels.

Role of Endophytic Actinomycetes in Crop Protection: Plant Growth Promotion and Biological Control

Endophytes are microorganisms that inhabit the interior of plant tissues without causing apparent disease in the host plant. The utilization of endophytic microorganisms for agricultural purposes has increased recently, especially in the biological control of insect-pest and plant disease and in plant growth promotion. Research has shown that many endophytic actinomycetes are beneficial to host plants with regard to the biological control of phytopathogens and plant growth promotion. Endophytic actinomycetes may promote plant growth by a combination of mechanisms, such as the solubilization of nutrients and the production of growth hormones and enzymes. Because actinomycetes are able to produce spores, a dissemination structure that offers resistance to many adverse conditions. These actinobacteria could be used for the formulation of novel bioinoculants composed of spores and/or mycelium. An understanding of the mechanisms enabling these endophytes to interact with host is important for realizing the potential of these microorganisms in agriculture production.

Anti-staphylococcal effectiveness of nisaplin in refrigerated pizza doughs

This study evaluated the effectiveness of nisaplin, commercial product having nisin as active component, in decreasing the staphylococcal population in refrigerated pizza doughs. The refrigerated pizza dough pieces randomly chosen were dipped in the solutions with nisaplin concentrations of 1.0 x 10-3 g and 1.0 x 10-2 g nisaplin/mL named for the treatment A and B and kept under refrigeration (7 °C ± 1 °C). On times 0, 15 and 30 days post treatment the Staphylococcus spp. count was carried out. The results showed that both nisaplin treatments were able to reduce the Staphylococcus spp. count (CFU/g) in the refrigerated pizza doughs. However, only treatment B showed statistically significant reducer effect (p < 0.05) on the count providing a decrease of 1.0 and 0.98 log cycles, respectively, after 15 and 30 days post treatment. These data suggest that nisin could appear as promising alternative to control the survival of the pathogen microorganisms in the foods, particularly, Staphylococcus in the refrigerated pizza doughs.

Endophytic Microorganisms of the Tropical Savannah: A Promising Source of Bioactive Molecules

The Brazilian tropical savannah, known as the “Cerrado”, is comprised of rich and characteristic flora, which makes it one of the 25 most important terrestrial biodiversity hotspots on the planet. This ecosystem is characterized by seasonal weather with annual precipitation that varies between 1200 and 1800 mm and a dry season that occurs during 5–6 months a year. This Brazilian savannah is a typical mosaic biome characterized by plants that can be endemic to this niche and several plant species that have medicinal properties and great pharmaceutical relevance. Although interest has increased in the microbial biodiversity associated with medicinal plants, the diversity, taxonomic composition, and biotechnological potential of endophytic microorganisms associated with these tropical plants from the savannah remain unclear. Plant-associated microorganisms such as endophytes are subjected to constant metabolic and environmental interactions, and these organisms should produce more secondary metabolites. These molecules are characterized by their diverse chemical structures and may be of use due to the wide range of their bioactivity against pathogens. The native plants of the Brazilian savannah are commonly used to treat skin diseases, ulcers, anemia, diabetes, malaria, inflammatory reactions, and hepatic diseases, and this medicinal flora has been used as folk medicine by different people as an alternative to high-priced pharmaceutical drugs. However, only a few of the medicinal Brazilian plants have been studied as a source of bioactive endophytic microbial communities. Several endophytes are important for microbial activities such as antibiotic capability against Gram-positive and Gram-negative bacteria, antifungal, antibiotic resistance, enzyme production, antitumor activity, and anti-Leishimania activity. The exploration of endophytes from new host hosts is important for assessing the potential of these microorganisms in different application areas and for emphasizing the potential of natural compounds that can be used in clinics and the pharmaceutical industry.