Leonardo Alberghini

Multiple-Locus Sequence Typing and Analysis of Toxin Genes in Bacillus cereus Food-Borne Isolates†

ABSTRACT In the present study we characterized 47 food-borne isolates of Bacillus cereus using multilocus sequence typing (MLST). Newly determined sequences were combined with sequences available in public data banks in order to produce the largest data set possible. Phylogenetic analysis was performed on a total of 296 strains for which MLST sequence information is available, and three main lineages—I, II, and III—within the B. cereus complex were identified. With few exceptions, all food-borne isolates were in group I. The occurrence of horizontal gene transfer (HGT) among various strains was analyzed by several statistical methods, providing evidence of widespread lateral gene transfer within B. cereus. We also investigated the occurrence of toxin-encoding genes, focusing on their evolutionary history within B. cereus. Several patterns were identified, indicating a pivotal role of HGT in the evolution of toxin-encoding genes. Our results indicate that HGT is an important element in shaping the population structure of the B. cereus complex. The results presented here also provide strong evidence of reticulate evolution within the B. cereus complex.

Heavy Metal Presence in Two Different Types of Ice Cream: Artisanal Ice Cream (Italian Gelato) and Industrial Ice Cream

Ice cream, a popular product worldwide, is usually a milk-based product with other types of ingredients (fruit, eggs, cocoa, dried fruit, additives, and others). Different materials are used to obtain the desired taste, texture, consistency, and appearance of the final product. This study surveyed ice cream products available in Italy for heavy metals (lead, cadmium, chromium, tin, and arsenic). The differences between artisanal and industrial ice cream were also investigated because of the importance in the Italian diet and the diffusion of this ready-to-eat food. Ice cream sampling was performed between October 2010 and February 2011 in the northeast of Italy. A total of 100 samples were randomly collected from different sources: 50 industrial samples produced by 19 different brands were collected in coffee bars and supermarkets; 50 artisanal ice cream samples were gathered at nine different artisanal ice cream shops. Ten wooden sticks of industrial ice cream were analyzed in parallel to the ice cream. All samples were negative for arsenic and mercury. None of the artisanal ice cream samples were positive for lead and tin; 18% of the industrial ice cream samples were positive. All positive lead samples were higher than the legal limit stated for milk (0.02 mg/kg). All industrial ice cream samples were negative for cadmium, but cadmium was present in 10% of the artisanal ice cream samples. Chromium was found in 26% of the artisanal and in 58% of the industrial ice cream samples. The heavy metals found in the wooden sticks were different from the corresponding ice cream, pointing out the lack of cross-contamination between the products. Considering the results and the amount of ice cream consumed during the year, contamination through ice cream is a low risk for the Italian population, even though there is need for further analysis.

Proximate composition, fatty acid profile, and heme iron and cholesterol content of rabbit meat as affected by sire breed, season, parity order, and gender in an organic production system

The study evaluated the effects of sire breed (SB: Vienna Blue (VB) and Burgundy Fawn (BF)), parity order (P: 1 = nulliparous, 2 = primiparous, ≥3 = multiparous), slaughter season (SS: spring, summer), and gender (G: males, females) on the meat quality of rabbits reared under an organic production system. They originated from VB and BF sires mated with females derived from a mix of crossbreds (mediumto large-sized breeds). Rabbits were 46 ± 6 days old, they were housed in groups of five in collective cages, fed a pelleted diet, and slaughtered at a live weight of 2.8 ± 0.13 kg. The hind leg meat samples (from 30 VB and 28 BF crossbred rabbits) were divided into two sub-samples: one was freshly packed in plastic bags, and the other was freeze-dried. Samples were stored at –20°C until analysis. The fresh hind leg samples were analyzed for heme iron and cholesterol contents, and fatty acid (FA) profiles. The freeze-dried hind leg samples were analyzed for proximate composition. Moisture and protein contents were affected by SS. The hind leg meat of rabbits slaughtered in summer showed lower moisture (P < 0.01), higher protein (P < 0.01), and lower cholesterol (P < 0.05) contents than that of rabbits slaughtered in spring. Meat of rabbits slaughtered in summer had less C14:0 (P < 0.05) and C16:0 FA (P < 0.01) and a higher proportion of total polyunsaturated FA (PUFA) (P < 0.001) due to n-6 FA (P < 0.01). The proportion of total saturated FA, C18:3 n-3 and C20:3 n-6 (P < 0.05), was influenced by gender. The BF crossbreed showed higher levels of total PUFA (P < 0.05) when reared in summer, primarily due to significant differences in C18:2 n-6 (P < 0.01) and C18:3 n-3 (P < 0.01). This study demonstrates that when rabbits are slaughtered in summer, their meat quality is better because the animals require longer time to reach the fixed slaughter weight; the meat is therefore characterized by a higher degree of maturity, with higher total PUFA and lower cholesterol contents.

Food as Cause of Human Salmonellosis

Foodborne salmonellosis is still today a serious public health issue: very common in poor developing countries, due to the bad general hygiene conditions, it is also largely widespread in developed countries. In the latter, 95% of recorded clinical cases are foodborne (Liu et al., 2011). According to EFSA epidemiological data (2011), in the European Union (EU) Salmonella is the second cause of foodborne disease after Campylobacter and it is still first in many EU States, such as Italy. Unlike Campylobacter, Salmonella often cause very large multistate outbreaks of food infection; this proves the greater resistance of this pathogen in the external environment and in food. In developed countries the main source of salmonellosis is still today food of animal origin, particularly meat (fresh and processed) and shell eggs. Also fresh fruits and vegetables can convey the bacteria to humans, as well as undrinkable water. Salmonella is quite resistant to adverse conditions and this allows them to persist in the environment and spread along the food chain, from the animals to the food of animal origin, or to plants that are fertilized with animal manure. Two species are currently registered into the genus Salmonella: S. enterica and S. bongori. The former is better adapted than the latter to live in the intestine of man and warm-blooded animals, whereas S. bongori travels in the external environment and is detectable in the intestinal contents of warm-blooded animals, so it is rare for it to be found in food for human consumption. The dangers for human health mainly arise from food contaminated with Salmonella enterica, which is often present in the intestines of livestock and pets, without causing any infection to the animals (“healthy carrier” condition). Humans can be healthy carriers of S. enterica in the intestine too. This may be a potential hazard to food hygiene, if the healthy carriers are the people involved in producing and handling the food. Usually a healthy carrier eliminates Salmonella in their faeces for several months after the episode of gastroenteritis through which they became carrier. In the case of Salmonella ser. Typhi, however, it has been demonstrated that humans can be asymptomatic carriers of the bacterium for decades (Weill, 2009). The genus Salmonella has more than 2,500 serotypes, and over 1,600 of these are within the enterica species, but not all serotypes have the same affinity for human and/or animals and they are not all found in the food that humans consume. Some serotypes (Typhy, Paratyphi A and C, some clones of Paratyphi B and Sendai) travel almost exclusively among men, and express their pathogenicity only when they infect a human being. Few serotypes travel exclusively among animals and do not infect humans, if not seldom (e.g. Abortusovis in sheep and Gallinarum-Pullorum in poultry). On the contrary, approximately 150 serotypes travel more or less constantly between the animal reservoir, the environment, food and man, starting from Salmonella ser. Typhimurium. Some serotypes, however, have a particular preference for some animal species: Enteritidis, Hadar, Heidelberg, Saintpaul,

Undeclared animal species in dry and wet novel and hydrolyzed protein diets for dogs and cats detected by microarray analysis

BackgroundAlthough the European Pet Food Industry Federation (FEDIAF) stated that labels must be accurate and provide detailed information on the ingredients, mislabeling of pet food has been documented by several authors. This phenomenon is of particular concern when related to products used as elimination diets for the diagnosis of adverse food reaction (AFR) in dogs and cats because the presence of undeclared ingredients may negatively interfere with the trial and prevent the veterinarian from making an appropriate diagnosis. The aim of this study was to shed light upon the problem of contamination and mislabeling in both dry and wet novel protein diets (NPDs) and hydrolyzed protein diets (HPDs) using a microarray-based commercial kit which tests for the presence of 19 animal species.ResultsOf the 40 analyzed products (9 dry NPDs, 22 wet NPDs, 6 dry HPDs and 3 wet HPDs), ten presented a content that correctly matched the label, while five did not contain the declared animal species, twenty-three revealed the presence of undeclared animal species, and two had a vague label that did not allow the evaluation of its accuracy. The most frequently contaminants identified in both dry and wet pet foods were pork, chicken and turkey. The presence of undeclared animal species was higher in dry than wet pet foods; furthermore, a lower number of contaminating animal species was identified in HPDs than NPDs (4 vs 10), and a lower number of contaminated HPDs (6 out of 9, 67%) than contaminated NPDs was detected (24 out of 31, 77%). Thirteen out of 14 brands tested presented at least one mislabeled product.ConclusionsMislabeling seems to be a widespread issue in pet foods used as elimination diets. Contamination can occur in all types of products used for the purpose, although dry NPDs are the main issue. Due to the high risk of contamination, particular attention should be given to both the selection of raw material suppliers and the production process.