Influence of different shrinking temperatures and vacuum conditions on the ability of psychrotrophic Clostridium to cause 'blown pack' spoilage in chilled vacuum-packaged beef

This study determined the ability of psychrotrophic Clostridium strains isolated from vacuum-packaged beefs and abattoir environments to cause 'blown-pack' spoilage of vacuum-packaged beef stored at 2 and 15 degrees C. The influence of shrinking temperatures (83, 84 and 87 degrees C) and vacuum pressure (6 and 9 mbar) on the occurrence of such spoilage as well as the effects of simulated transportation (500 km) on the integrity of packages was determined. At 15 degrees C and 2 degrees C, twelve and six strains caused 'blown-pack' spoilage, respectively. The combination of vacuum pressure (9 mbar) combined with shrinking temperature (87 degrees C) retarded the occurrence of spoilage. The simulated transportation under the experimental conditions did not affect the integrity of packages. More studies that assess the factors that may contribute for the occurrence of 'blown-pack' spoilage should be performed to avoid the occurrence of such spoilage during its shelf-life. (C) 2012 Elsevier Ltd. All rights reserved.

Molecular typing of Clostridium perfringens isolated from swine in slaughterhouses from Sao Paulo State, Brazil

Clostridium perfringens is an anaerobic Gram-positive bacterium known as common pathogen for humans, for domestic and wildlife animals. Although infections caused by C. perfringens type C and A in swine are well studied, just a few reports describe the genetic relationship among strains in the epidemiological chain of swine clostridioses, as well as the presence of the microorganism in the slaughterhouses. The aim of the present study was to isolate C. perfringens from feces and carcasses from swine slaughterhouses, characterize the strains in relation to the presence of enterotoxin, alpha, beta, epsilon, iota and beta-2 toxins genes. using polymerase chain reaction (PCR) and comparing strains by means of Pulsed field gel electrophoresis (PFGE). Clostridium perfringens isolation frequencies in carcasses and finishing pig intestines were of 58.8% in both types of samples. According to the polymerase chain reaction assay, only, alfa toxin was detected, being all isolates also negative to enterotoxin and beta2 toxin. Through PFGE technique, the strains were characterized in 35 pulsotypes. In only one pulsotype, the isolate from carcass sample was grouped with fecal isolate of the same animal, suggesting that the risk of cross-contamination was low. Despite the high prevalence of C. perfringens in swine carcasses from the slaughterhouses assessed, the risk of food poisoning to Brazilian pork consumers is low, since all strains were negative to cpe-gene, codifying enterotoxin.

Molecular typing of Clostridium perfringens isolated from swine in slaughterhouses from São Paulo State, Brazil

Clostridium perfringens is an anaerobic Gram-positive bacterium known as common pathogen for humans, for domestic and wildlife animals. Although infections caused by C. perfringens type C and A in swine are well studied, just a few reports describe the genetic relationship among strains in the epidemiological chain of swine clostridioses, as well as the presence of the microorganism in the slaughterhouses. The aim of the present study was to isolate C. perfringens from feces and carcasses from swine slaughterhouses, characterize the strains in relation to the presence of enterotoxin, alpha, beta, epsilon, iota and beta-2 toxins genes, using polymerase chain reaction (PCR) and comparing strains by means of Pulsed field gel electrophoresis (PFGE). Clostridium perfringens isolation frequencies in carcasses and finishing pig intestines were of 58.8% in both types of samples. According to the polymerase chain reaction assay, only alfa toxin was detected, being all isolates also negative to enterotoxin and beta2 toxin. Through PFGE technique, the strains were characterized in 35 pulsotypes. In only one pulsotype, the isolate from carcass sample was grouped with fecal isolate of the same animal, suggesting that the risk of cross-contamination was low. Despite the high prevalence of C. perfringens in swine carcasses from the slaughterhouses assessed, the risk of food poisoning to Brazilian pork consumers is low, since all strains were negative to cpe-gene, codifying enterotoxin.

Distribution of sewage input in marine sediments around a maritime Antarctic research station indicated by molecular geochemical indicators

Sediments from Admiralty Bay, Antarctica were collected during the austral summers of 2002/2003 and 2003/2004 in order to assess the distribution and concentration of sewage indicators originating from Comandante Ferraz Brazilian Antarctic Station. Fecal sterols (coprostanol + epicoprostanol) and linear alkylbenzenes (LABs) ranged from <0.01 to 0.95 mu g g(-1) and <1.0 to 23 ng g(-1) dry weight, respectively. In general, the higher concentrations were found only locally in the vicinity of Ferraz station at Martel Inlet. Baseline values for fecal sterols and coprostanone were calculated as 0.19 and 0.40 mu g g(-1), respectively. According to fecal sterols concentrations, sewage contribution to Martel Inlet has increased more than twice since 1997, as result of the increase in the number of researchers at the station especially during the last decade. A low correlation was found between total LABs and fecal steroids, which could be attributed to the contribution of the natural sources of steroids. (C) 2010 Elsevier B.V. All rights reserved.

Establishment of the bacterial fecal community during the first month of life in Brazilian newborns

OBJECTIVE: The establishment of the intestinal microbiota in newborns is a critical period with possible long-term consequences for human health. In this research, the development of the fecal microbiota of a group of exclusively breastfed neonates living in low socio-economic conditions in the city of Sao Paulo, Brazil, during the first month of life, was studied. METHODS: Fecal samples were collected from ten neonates on the second, seventh, and 30th days after birth. One of the neonates underwent antibiotic therapy. Molecular techniques were used for analysis; DNA was extracted from the samples, and 16S rRNA libraries were sequenced and phylogenetically analyzed after construction. A real-time polymerase chain reaction (PCR) was performed on the samples taken from the 30th day to amplify DNA from Bifidobacterium sp. RESULTS: The primary phylogenetic groups identified in the samples were Escherichia and Clostridium. Staphylococcus was identified at a low rate. Bifidobacterium sp. was detected in all of the samples collected on the 30th day. In the child who received antibiotics, a reduction in anaerobes and Escherichia, which was associated with an overgrowth of Klebsiella, was observed throughout the experimental period. CONCLUSION: The observed pattern of Escherichia predominance and reduced Staphylococcus colonization is in contrast with the patterns observed in neonates living in developed countries.

Performance and composition of bacterial communities in anaerobic fluidized bed reactors for hydrogen production: Effects of organic loading rate and alkalinity

This study evaluated the effects of the organic loading rate (OLR) and pH buffer addition on hydrogen production in two anaerobic fluidized bed reactors (AFBRs) operated simultaneously. The AFBRs were fed with glucose, and expanded clay was used as support material. The reactors were operated at a temperature of 30 degrees C, without the addition of a buffer (AFBR1) and with the addition of a pH buffer (AFBR2, sodium bicarbonate) for OLRs ranging from 19.0 to 140.6 kg COD m(-3) d(-1) (COD: chemical oxygen demand). The maximum hydrogen yields for AFBR1 and AFBR2 were 2.45 and 1.90 mol H-2 mol(-1) glucose (OLR of 84.3 kg COD m(-3) d(-1)), respectively. The highest hydrogen production rates were 0.95 and 0.76 L h(-1) L-1 for AFBR1 and AFBR2 (OLR of 140.6 kg COD m(-3) d(-1)), respectively. The operating conditions in AFBR1 favored the presence of such bacteria as Clostridium, while the bacteria in AFBR2 included Clostridium, Enterobacter, Klebsiella, Veillonellaceae, Chryseobacterium, Sporolactobacillus, and Burkholderiaceae. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Dissecting structure-function-stability relationships of a thermostable GH5-CBM3 cellulase from Bacillus subtilis 168

Cellulases participate in a number of biological events, such as plant cell wall remodelling, nematode parasitism and microbial carbon uptake. Their ability to depolymerize crystalline cellulose is of great biotechnological interest for environmentally compatible production of fuels from lignocellulosic biomass. However, industrial use of cellulases is somewhat limited by both their low catalytic efficiency and stability. In the present study, we conducted a detailed functional and structural characterization of the thermostable BsCe15A (Bacillus subtilis cellulase 5A), which consists of a GH5 (glycoside hydrolase 5) catalytic domain fused to a CBM3 (family 3 carbohydrate-binding module). NMR structural analysis revealed that the Bacillus CBM3 represents a new subfamily, which lacks the classical calcium-binding motif, and variations in NMR frequencies in the presence of cellopentaose showed the importance of polar residues in the carbohydrate interaction. Together with the catalytic domain, the CBM3 forms a large planar surface for cellulose recognition, which conducts the substrate in a proper conformation to the active site and increases enzymatic efficiency. Notably, the manganese ion was demonstrated to have a hyper-stabilizing effect on BsCel5A, and by using deletion constructs and X-ray crystallography we determined that this effect maps to a negatively charged motif located at the opposite face of the catalytic site.

Acute heat stress impairs performance parameters and induces mild intestinal enteritis in broiler chickens: Role of acute hypothalamic-pituitary-adrenal axis activation

Studies on the environmental consequences of stress are relevant for economic and animal welfare reasons. We recently reported that long-term heat stressors (31 +/- 1 degrees C and 36 +/- 1 degrees C for 10 h/d) applied to broiler chickens (Gallus gallus domesticus) from d 35 to 42 of life increased serum corticosterone concentrations, decreased performance variables and the macrophage oxidative burst, and produced mild, multifocal acute enteritis. Being cognizant of the relevance of acute heat stress on tropical and subtropical poultry production, we designed the current experiment to analyze, from a neuroimmune perspective, the effects of an acute heat stress (31 +/- 1 degrees C for 10 h on d 35 of life) on serum corticosterone, performance variables, intestinal histology, and peritoneal macrophage activity in chickens. We demonstrated that the acute heat stress increased serum corticosterone concentrations and mortality and decreased food intake, BW gain, and feed conversion (P < 0.05). We did not find changes in the relative weights of the spleen, thymus, and bursa of Fabricius (P > 0.05). Increases in the basal and the Staphylococcus aureus-induced macrophage oxidative bursts and a decrease in the percentage of macrophages performing phagocytosis were also observed. Finally, mild, multifocal acute enteritis, characterized by the increased presence of lymphocytes and plasmocytes within the lamina propria of the jejunum, was also observed. We found that the stress-induced hypothalamic-pituitary-adrenal axis activation was responsible for the negative effects observed on chicken performance and immune function as well as for the changes in the intestinal mucosa. The data presented here corroborate with those presented in other studies in the field of neuroimmunomodulation and open new avenues for the improvement of broiler chicken welfare and production performance.

Microbiota benefits after inulin and partially hydrolized guar gum supplementation - a randomized clinical trial in constipated women

Introduction: Prebiotics positively affect gut microbiota composition, thus improving gut function. These properties may be useful for the treatment of constipation. Objectives: This study assessed the tolerance and effectiveness of a prebiotic inulin/partially hydrolyzed guar gum mixture (I-PHGG) for the treatment of constipation in females, as well as its influence on the composition of intestinal microbiota and production of short chain fatty acids. Methods: Our study enrolled 60 constipated female health worker volunteers. Participants reported less than 3 bowel movements per week. Volunteers were randomized to treatment with prebiotic or placebo. Treatment consisted of 3 weeks supplementation with 15 g/d I-PHGG (fiber group) or maltodextrin (placebo group). Abdominal discomfort, flatulence, stool consistency, and bowel movements were evaluated by a recorded daily questionnaire and a weekly interview. Changes in fecal bacterial population and short chain fatty acids were assessed by real-time PCR and gas chromatography, respectively. Results: There was an increased frequency of weekly bowel movements and patient satisfaction in both the fiber and placebo groups with no significant differences. Total Clostridium sp significantly decreased in the fiber group (p = 0.046) and increased in the placebo group (p = 0.047). There were no changes in fecal short chain fatty acid profile. Conclusions: Consumption of I-PHGG produced clinical results comparable to placebo in constipated females, but had additional protective effects on gut rnicrobiota by decreasing the amount of pathological bacteria of the Clostridium genera.

Impact of Protease Inhibitors on Dentin Matrix Degradation by Collagenase

This proof-of-concept study assessed whether the reduction of the degradation of the demineralized organic matrix (DOM) by pre-treatment with protease inhibitors (PI) is effective against dentin matrix loss. Bovine dentin slices were demineralized with 0.87 M citric acid, pH 2.3, for 36 hrs. In sequence, specimens were treated or not (UT, untreated) for 1 min with gels containing epigallocatechin 3-gallate (EGCG, 400 A mu M), chlorhexidine (CHX, 0.012%), FeSO4 (1 mM), NaF (1.23%), or no active compound (P, placebo). Specimens were then stored in artificial saliva (5 days, 37 degrees C) with the addition of collagenase (Clostridium histolyticum, 100 U/mL). We analyzed collagen degradation by assaying hydroxyproline (HYP) in the incubation solutions (n = 5) and evaluated the dentin matrix loss by profilometry (n = 12). Data were analyzed by ANOVA and Tukey's test (p < 0.05). Treatment with gels containing EGCG, CHX, or FeSO4 led to significantly lower HYP concentrations in solution and dentin matrix loss when compared with the other treatments. These results strongly suggest that the preventive effects of the PI tested against dentin erosion are due to their ability to reduce the degradation of the DOM.

Gases and volatile compounds associated with micro-organisms in blown pack spoilage of Brazilian vacuum-packed beef

This study correlated the composition of the spoilage bacterial flora with the main gaseous and volatile organic compounds (VOCs) found in the package headspace of spoiled, chilled, vacuum-packed meat. Fifteen chilled, vacuum-packed beef samples, suffering from blown pack spoilage, were studied using 16S rRNA clone sequencing. More than 50% of the bacteria were identified as lactic acid bacteria (LAB), followed by clostridia and enterobacteria. Fifty-one volatile compounds were detected in the spoiled samples. Although the major spoilage compounds were identified as alcohols and aldehydes, CO2 was identified as the major gas in the spoiled samples by headspace technique. Different species of bacteria contribute to different volatile compounds during meat spoilage. LAB played an important role in blown pack deterioration of the Brazilian beef studied.