Molecular typing and virulence markers of Yersinia enterocolitica strains from human, animal and food origins isolated between 1968 and 2000 in Brazil

Molecular typing and virulence markers were used to evaluate the genetic profiles and virulence potential of 106 Yersinia enterocolitica strains. of these strains, 71 were bio-serotype 4/O: 3, isolated from human and animal clinical material, and 35 were of biotype 1 A or 2 and of diverse serotypes, isolated from food in Brazil between 1968 and 2000. Drug resistance was also investigated. All the strains were resistant to three or more drugs. The isolates showed a virulence-related phenotype in the aesculin, pyrazinamidase and salicin tests, except for the food isolates, only two of which were positive for these tests. For the other phenotypic virulence determinants (autoagglutination, Ca++ dependence and Congo red absorption), the strains showed a diverse behaviour. The inv, ail and ystA genes were detected in all human and animal strains, while all the food isolates were positive for inv, and 3% of them positive for ail and ystA. The presence of virF was variable in the three groups of strains. The strains were better discriminated by PFGE than by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). A higher genomic similarity was observed among the 4/O: 3 strains, isolated from human and animal isolates, than among the food strains, with the exception of two food strains possessing the virulence genes and grouped close to the 4/O: 3 strains by ERIC-PCR. Unusually, the results revealed the virulence potential of a bio-serotype 1 A/O: 10 strain, suggesting that food contaminated with Y. enterocolitica biotype 1 A may cause infection. This also suggests that ERIC-PCR may be used as a tool to reveal clues about the virulence potential of Y. enterocolitica strains. Furthermore, the results also support the hypothesis that animals may act as reservoirs of Y. enterocolitica for human infections in Brazil, an epidemiological aspect that has not been investigated in this country, confirming data from other parts of the world.

Quality and safety of oils and fats obtained as co-products or by-products of the food chain and destined to animal production

The aim of the first part of this thesis was to evaluate the effect of trans fatty acid- (TFA), contaminant, polycyclic aromatic hydrocarbon (PAH)- and oxidation productenriched diets on the content of TFA and conjugated linoleic acid (CLA) isomers in meat and liver of both poultry and rabbit. The enriched feedings were prepared with preselected fatty co-and by-products that contained low and high levels of TFA (low, palm fatty acid distillate; high, hydrogenated palm fatty acid distillate), environmental contaminants (dioxins and PCBs) (two different fish oils), PAH (olive oil acid oils and pomace olive oil from chemical refining, for low and high levels) and oxidation products (sunflower-olive oil blend before and after frying), so as to obtain single feedings with three enrichment degrees (high, medium and low) of the compound of interest. This experimental set-up is a part of a large, collaborative European project (http://www.ub.edu/feedfat/), where other chemical and health parameters are assessed. Lipids were extracted, methylated with diazomethane, then transmethylated with 2N KOH/methanol and analyzed by GC and silver-ion TLC-GC. TFA and CLA were determined in the fats, the feedings, meat and liver of both poultry and rabbit. In general, the level of TFA and CLA in meat and liver mainly varied according to those originally found in the feeding fats. It must be pointed out, though, that TFA and CLA accumulation was different for the two animal species, as well as for the two types of tissues. The TFA composition of meat and liver changes according to the composition of the oils added to the feeds with some differences between species. Chicken meat with skin shows higher TFA content (2.6–5.4 fold) than rabbit meat, except for the “PAH” trial. Chicken liver shows higher TFA content (1.2–2.1 fold) than rabbit liver, except for the “TRANS” and “PAH” trials. In both chicken and rabbit meats, the TFA content was higher for the “TRANS” trial, followed by the “DIOXIN” trial. Slight differences were found on the “OXIDATION” and “PAH” trends in both types of meats. In both chicken and rabbit livers, the TFA content was higher for the “TRANS” trial, followed by those of the “PAH”, “DIOXIN” and “OXIDATION” trials. This trend, however, was not identical to that of feeds, where the TFA content varied as follows: “TRANS” > “DIOXIN” >“PAH” > “OXIDATION”. In chicken and rabbit meat samples, C18:1 TFA were the most abundant, followed by C18:2 TFA and C18:3 TFA, except for the “DIOXIN” trial where C18:3 TFA > C18:2 TFA. In chicken and rabbit liver samples of the “TRANS” and “OXIDATION” trials, C18:1 TFA were the most abundant, followed by C18:2 TFA and C18:3 TFA, whereas C18:3 TFA > C18:2 in the “DIOXIN” trial. Slight differences were found on the “PAH” trend in livers from both species. The second part of the thesis dealt with the study of lipid oxidation in washed turkey muscle added with different antioxidants. The evaluation on the oxidative stability of muscle foods found that oxidation could be measured by headspace solid phase microestraction (SPME) of hexanal and propanal. To make this method effective, an antioxidant system was added to stored muscle to stop the oxidative processes. An increase in ionic strength of the sample was also implemented to increase the concentration of aldehydes in the headspace. This method was found to be more sensitive than the commonly used thiobarbituric acid reactive substances (TBARs) method. However, after antioxidants were added and oxidation was stopped, the concentration of aldehydes decreased. It was found that the decrease in aldehyde concentration was due to the binding of the aldehydes to muscle proteins, thus decreasing the volatility and making them less detectable.

Food lipids: their effects on quality and oxidative stability of animal tissues and emulsions

Lipolysis and oxidation of lipids in foods are the major biochemical and chemical processes that cause food quality deterioration, leading to the characteristic, unpalatable odour and flavour called rancidity. In addition to unpalatability, rancidity may give rise to toxic levels of certain compounds like aldehydes, hydroperoxides, epoxides and cholesterol oxidation products. In this PhD study chromatographic and spectroscopic techniques were employed to determine the degree of lipid oxidation in different animal products and its relationship with technological parameters like feeding fat sources, packaging, processing and storage conditions. To achieve this goal capillary gas chromatography (CGC) was employed not only to determine the fatty acids profile but also, after solid phase extraction, the amount of sterols (cholesterol and phytosterols) and cholesterol oxidation products (COPs). To determine hydroperoxides, primary products of oxidation and quantify secondary products UV/VIS absorbance spectroscopy was applied. Beef and pork meat in this study were analysed. In actual fact, lipid oxidation is a major deterioration reaction in meat, meat products and results in adverse changes in the colour, flavour, texture of meat and develops different compounds which should be a risk to human health as oxysterols. On beef and pork meat, a study of lipid fraction during storage was carried out to evaluate its shelf-life and some nutritional features life saturated/unsaturated fatty acids ratio and sterols content, in according to the interest that has been growing around functional food in the last years. The last part of this research was focused on the study of lipid oxidation in emulsions. In oil-in-water emulsions antioxidant activity of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) was evaluated. The rates of lipid oxidation of 1.0% stripped soybean oil-in-water emulsions with DOPC were followed by monitoring lipid hydroperoxide and hexanal as indicators of primary and secondary oxidation products and the droplet surface charge or zeta potential (ζ) of the emulsions with varying concentrations of DOPC were tested. This manuscript reports the main results obtained in the three activities briefly summarized as follows: 1. study on effects of feeding composition on the photoxidative stability of lipids from beef meat, evaluated during storage under commercial retail conditions; 2. evaluation of effects of diets and storage conditions on the oxidative stability of pork meat lipids; 3. study on oxidative behavior of DOPC in stripped soybean oil-in-water emulsions stabilized by nonionic surfactant.

Lipid quality and oxidative stability in food products from animal origin, as affected by breeding factor

Nowadays it is requested more investigations on alternative rearing systems that are able to improve poultry welfare and to warrant high-quality and safe meat products. This thesis work was focused on the evaluation of the oxidative stability of poultry meats, obtained with different rearing systems, diets (supplemented with bioactive compounds), and packaging conditions. The thesis work was divided into the following parts: - Evaluation of the effects of different rearing systems on the quality, fatty acid composition and oxidative stability of poultry thigh and breast meat belonging to different product categories (“rotisserie” and “cut-up” carcasses); - Evaluation of the effects of different rearing systems and packaging conditions on the shelf-life of poultry thigh meat stored at 4°C for 14 days, and the effects of feed supplementation with thymol (control diet and diet with 2 different concentration of thymol) and packaging conditions on lipid oxidation of poultry thigh meat shelf-life (stored at 4°C for 14 days). The oxidative stability of poultry meat was studied by means of the spectrophotometric determinations of peroxide value and thiobarbituric acid reactive substances. - Evaluation of anti-inflammatory effects of different flavonoids (thymol, luteolin, tangeretin, sulforaphane, polymethoxyflavones, curcumin derivates) to detect their biological activity in LPS-stimulated RAW 264.7 macrophage cells in vitro, in order to study more in depth their action mechanisms. It was evaluated the cell vitality (MTT assay), nitrite concentration and protein profile. The study was focused on the identification of potential dietary bioactive compounds in order to investigate their biological activity and possible synergic effects, and to develop new suitable strategies for long-term promotion of human health, in particular against cancer.

Where Is My Food? Brazilian Flower Fly Steals Prey from Carnivorous Sundews in a Newly Discovered Plant-Animal Interaction

A new interaction between insects and carnivorous plants is reported from Brazil. Larvae of the predatory flower fly Toxomerus basalis (Diptera: Syrphidae: Syrphinae) have been found scavenging on the sticky leaves of several carnivorous sundew species (Drosera, Droseraceae) in Minas Gerais and São Paulo states, SE Brazil. This syrphid apparently spends its whole larval stage feeding on prey trapped by Drosera leaves. The nature of this plant-animal relationship is discussed, as well as the Drosera species involved, and locations where T. basalis was observed. 180 years after the discovery of this flower fly species, its biology now has been revealed. This is (1) the first record of kleptoparasitism in the Syrphidae, (2) a new larval feeding mode for this family, and (3) the first report of a dipteran that shows a kleptoparasitic relationship with a carnivorous plant with adhesive flypaper traps. The first descriptions of the third instar larva and puparium of T. basalis based on Scanning Electron Microscope analysis are provided.

The curiosities of food; or, The dainties and delicacies of different nations obtained from the animal kingdom.

Mode of access: Internet.

Report to the Commissioner of the Food and Drug Administration by the FDA Task Force on the use of antibiotics in animal feeds.

Appended: Press briefing by Commissioner Charles C. Edwards and by C. D. Van Houweling.

Travelers' tips on bringing food, plant, and animal products into the United States.

Mode of access: Internet.