No abstract

Listeriosis is a serious foodborne disease caused by Listeria monocytogenes, a pathogen often found in food processing plants. Poultry meat and its derivatives may harbor L. monocytogenes even if good manufacturing practices are implanted in abattoirs. Little information exists in Brazil on the frequency of L. monocytogenes contamination, even though the country is considered the top poultry meat exporter in the world. This study attempted to compare 2 exporters poultry facilities following same the standards but differing only in manual (plant M) or automatic (plant A) evisceration. Eight hundred fifty-one samples from food, food contact and non-food contact surfaces, water, and workers' hands were collected from cage to finished products over a 1-yr period. In plant A, 20.1% of the samples were positive for L. monocytogenes, whereas in plant M, 16.4% was found. The greatest incidence of contamination with the pathogen in plant A was found in non-food contact surfaces (27.3%), while in plant M, it was found in products (19.4%). The most prevalent serovars were 1/2a or 3a (plant M) and 4b, 4d, or 4e (plant A). Despite having proper hygiene and good manufacturing practices, controlling the entry and persistence of L. monocytogenes in processing facilities remains a formidable task.

Brazil is the first exporter of chicken meat and the third producer of this kind of meat in the world. The consumption of this protein source in Brazil has been increasing, having passed from 23.2 Kg/inhabitant in 1995 to 35.5 Kg/inhabitant in 2005. The international market has become more demanding for safety of these products. Because of the importance of this food commodity to Brazilian economy and because of Listeria monocytogenes importance as a foodborne pathogen this study was conducted. The presence of the pathogen in two facilities, one with automatic evisceration (Plant A) and another with manual evisceration (Plant M), was evaluated to identify possible routes of microorganism dissemination in the processing line. From a total of 851 collected samples of products, food contact and non-food contact surfaces, workers' hands and water used in the process, 423 samples were from Plant A and 428 from Plant M. VIP ® Listeria was used for the samples screening, positive ones were plated and suspected characteristic colonies submitted to biochemical characterization. Selected strains were submitted to identification and typing by molecular techniques (BAX ® System, multiplex-PCR 16S rRNA, multiplex-PCR, ribotyping and PFGE). L. monocytogenes was isolated in 20.1% of the samples from Plant A with 61.6% belonging to serogroup 4b, 4d or 4e; 19.2% to serogroup 1/2a or 3a; 15.2% to serogroup 1/2c or 3c; and 4.0% to serogroup 1/2b, 3b or 7. From Plant M 16.4% of the samples were positive for L. monocytogenes, with predominance of serogroup 1/2a or 3a (72.9%) followed by serogroup 4b, 4d or 4e (27.1%). Based on the results of phenotypic and genotypic characterization, it was verified that L. monocytogenes present in the final product had similar characteristics to those isolated in the plant, and not in the animals. Only one strain was isolated in the dirty zone of Plant A, on the floor of defeathering section, and all others were isolated in the clean zone of both plants.

Linguiça is a highly popular and appreciated pork product in Brazil, frequently consumed undercooked. Aiming at collection of data for a future risk assessment, this study evaluated the prevalence and counts of Listeria monocytogenes in linguiça samples collected at retail level in Sao Paulo, SP, Brazil. ISO methods were used for detection and enumeration of the pathogen (11290-1 and 11290-2, respectively). Isolates were submitted to Simplex-PCR for hlyA gene and those with biochemical features of L. monocytogenes and hlyA positive were serotyped using a Multiplex PCR. Ninety percent of the samples were positive for Listeria spp., and L. monocytogenes was detected in 42% of the samples, with counts below 10(2)CFU/g in all samples. A prevalence of uncommon serotypes 4a and 4c was observed.

A study was conducted to evaluate a high pressure spray (HPS) with water as an alternative to trimming to remove gastrointestinal contamination on poultry carcasses and improve microbiological quality. The study was conducted under commercial conditions in 5 slaughter plants with one plant presenting approximately 5% of carcasses with visible gastrointestinal contamination (VGC), and the others showing approximately 12% of VGC. In all 5 plants, carcasses were sampled from the slaughter line and separated into 6 groups corresponding to 3 different treatments: A) carcasses with VGC before and after trimming; B) carcasses with VGC before and after HPS; and C) carcasses with no VGC before and after HPS. At the end of Trial A and prior to Trials B and C, an HPS equipment was installed before the end of the slaughter line. The HPS equipment was operated with 10 kgf/cm² of pressure and 1.5 L of potable water per carcass. Carcasses were analyzed using a rinsing procedure, and the following microbiological parameters were evaluated: the prevalence of Salmonella and Campylobacter, the abundance of Escherichia coli (EC), Enterobacteriaceae (EB), and the Total Viable Count (TVC). Salmonella was found in all plants at a prevalence ranging from 0.8% (plant 1) to 17.3% (plant 5), and the difference between plants was significant (P < 0.05%). The prevalence of Campylobacter ranged from 2.1 (plant 1) to 18.6% (plant 4) (P < 0.05%). The prevalence of Campylobacter was similar in plants 2, 3, and 5, and a significant difference (P < 0.05%) was observed compared to plants 1 and 4. In all plants, the EC, EB, and TVC counts did not show a significant difference (P > 0.05%) in any treatments. These results demonstrate that HPS with water is an alternative method for removing VGC and improving or maintaining the microbiological quality and safety of broiler carcasses.

The recombinant green fluorescent protein (gfp(uv)) was expressed by Escherichia coli DH5-alpha cells transformed with the plasmid pGFPuv. The gfp(uv) was selectively permeabilized from the cells in buffer solution (25 mM Tris-HCl, pH 8.0), after freezing (-70 degrees C for 15 h), by four freeze (-20 degrees C)/thaw cycles interlaid by sonication. The average content of released gfp(uv) (experiment 2) was 7.76, 34.58, 39.38, 12.90, and 5.38%, for the initial freezing (-70 degrees C) and the first, second, third and fourth freeze/thaw cycles, respectively. Superfusion on freezing was observed between -11 degrees C and -14 degrees C, after which it reached -20 degrees C at 0.83 degrees C/min.

O aumento do uso da proteína verde fluorescente (GFPuv) como ferramenta de pesquisas biotecnológicas requer um estudo mais cuidadoso das propriedades bioquímicas e físicas da molécula de GFPuv. Este trabalho teve como objetivo a aplicação de métodos físicos e químicos para o isolamento, a extração da GFPuv de células de Escherichia coli DH5-α, purificação da proteína, e o estudo da estabilidade desta em diferentes valores de pH. Células de E. coli expressando GFPuv foram submetidas a quatro ciclos sucessivos de congelamento e descongelamento intercalados por sonicação (CDS), para promover a permeação seletiva da GFPuv. Os permeados foram submetidos à extração por partição em três fases (TPP) e posterior purificação por eluição da proteína em coluna cromatográfica de interação hidrofóbica (HIC).Obteve-se rendimento semelhante em GFPuv no 1 o ciclo de permeação seletiva (CDS) e por extração (TPP) associada à purificação (HIC) para os quais impurezas não foram visualizadas por eletroforese. As estruturas moleculares da GFPuv extraída e purificada mostraramse inalteradas em valores de pH entre 6,0 e 9,8, e foram confirmadas nos espectros de emissão e de excitação.

The aim of this study was to isolate new bacteriocin-producing lactic acid bacteria (LAB) from goat milk and cheeses produced in Sao Paulo State, Brazil, with activity against Listeria monocytogenes. Samples of goat milk obtained from a farm (Sitio Rekantinho, Ibiúna, SP, Brazil) and goat cheeses obtained from a local supermarket (Butanta, Sao Paulo, SP, Brazil) were screened for presence of bacteriocin-producing LAB. Based on preliminary inhibition tests performed using the three levels method described by Todorov (2008), more than 30% of the LAB colonies isolated from these products were potential bacteriocin producers. These colonies were isolated and confirmed for bacteriocin production using L. monocytogenes ScottA, L. monocytogenes ATCC 7644 and L. innocua USP FCF 01 as indicators of inhibitory activity. A total of 14 isolates were selected and identified based on API 50 CHL and 16S rRNA sequencing. The bacteriocins of all 14 isolates inhibited the growth of a large number of L. monocytogenes strains from different serological groups. The highest bacteriocins production was recorded during the beginning of stationary growth phase and remained stable for at least 24 h at 30 o C. Treatment of the cell-free supernatants with proteolytic enzymes inhibited the antimicrobial activity of the bacteriocins. No significant changes in bacteriocin activity of all 14 isolates were recorded when they were exposed to pH from 2.0 to 12.0, and to temperatures from 25 o C to 100 o C for 2h. These LAB strains present an interesting potential of application as biotechnological tools for improvement of the microbiological safety of goat cheeses.