Estimate of mercury and methyl mercury intake associated with fish consumption from Sagua la Grande River,Cuba

This paper provides an estimate of the weekly intake of total mercury (THg) and methyl mercury (MeHg) from consumption of fish from the Sagua la Grande River, Villa Clara, Cuba, by determining the THg levels in different fish species. The levels varied between 0.143 and 0.484 μg g^?1 on a fresh weight basis. None of the analysed fish was found to have levels above the national and international regulatory levels, although THg levels over 0.2 μg g^?1, the threshold concentration established by the World Health Organization (WHO) for the consumption by vulnerable population groups, were found in 75% of samples. The MeHg level was found to be 84% of the THg content. A Food Frequency Survey was given to 127 townspeople to estimate river fish consumption. The weekly intake of MeHg was found to be greater than the value established by the provisional tolerable weekly intake (PTWI) in 50% of children, in 80% of pregnant women, and in 75% of women in childbearing age. These weekly intakes can represent an important risk to the population's health, especially for vulnerable groups.     

Antibiotic resistance of coagulase-negative staphylococci associated with food and used in starter cultures

The resistance of 330 coagulase-negative staphylococci (CNS) associated with food or used in starter cultures and belonging to the species Staphylococcus carnosus, Staphylococcus condimenti, Staphylococcus piscifermentans, Staphylococcus equorum, Staphylococcus succinus and Staphylococcus xylosus, against 21 antibiotics was determined using the disk diffusion method. The incidence and number of resistances was found to be species and source of isolation dependent. Most strains of S. equorum (63%), S. succinus (90%) and S. xylosus (95%) exhibited resistances against up to seven antibiotics, whereas only few strains of S. carnosus (12%) and S. piscifermentans (27%) were antibiotic resistant. Resistances to lincomycin, penicillin, fusidic acid, oxacillin, ampicillin and tetracycline were predominant. Among strains of S. xylosus, the incidence of resistance ranged from 22% for tetracycline up to 69% for penicillin. Concerning the source of isolation, resistances were often determined in strains of S. equorum, S. succinus and S. xylosus isolated from cheese (87%) and sausage (83%), and strains of S. xylosus obtained from meat starter cultures (93%). Remarkably, all CNS were sensitive to the clinically important antibiotics chloramphenicol, clindamycin, cotrimoxazol, gentamicin, kanamycin, linezolid, neomycin, streptomycin, synercid and vancomycin. The phenotypic resistances to ss-lactam antibiotics, lincomycin and tetracycline were verified by PCR amplification and could be traced back to the genes blaZ, lnuA and tetK, respectively. This study permitted a comprehensive insight into the incidence of antibiotic resistances in food-associated CNS.     

Antibiotic resistance profiling and valorization of food waste streams to starter culture biomass and exopolysaccharides through fed-batch fermentations

Food Science and Biotechnology - The present study evaluated antibiotic resistance (ABR) in bacteria isolated from different food wastes viz., meat slaughterhouses, dairy and restaurants. About 120...     

市售即食食品中非致病菌的耐药性及耐药基因转移的研究

目的 了解西安市即食食品中的非致病菌的耐药性分布、耐药程度及耐药基因的转移情况,分析潜在的食品安全问题.方法 对西安市的几家大型超市零售的熟肉、果盘、凉拌菜3大类即食食品样品进行食源性非致病菌的红霉素和氨苄青霉素耐药性分析、耐药基因转移、菌株16 S rRNA序列测序鉴定等.结果 42.5％的分离株具有不同程度的红霉素耐药性,47.5％的分离株具有不同程度的氨苄青霉素耐药性,21.2％的分离株同时具有2种抗生素耐药性;11.3％的红霉素耐药株耐药性高达160 mg/L,6.3％的氨苄青霉素耐药株耐药性高达500 mg/L.随机挑选的部分耐药株在无抗生素培养基中连续传代1000代以后,60％的氨苄青霉素耐药株和45％的红霉素耐药株的耐药性消失.部分耐药株的耐药基因可水平转移至非耐药株中.这些耐药株多为肠球菌、葡萄球菌、芽孢杆菌、假单胞菌等.结论 即食食品中的非致病菌有潜在的风险,耐药基因在细菌间的转移可能对人体敏感肠道菌群和致病菌有一定影响.     

Salmonella typhimurium resistance on pulsed electric fields associated with membrane fluidity and gene regulation

Effects of different growth temperatures on cytoplasmic membrane fluidity and phospholipids phase transition temperature (T_m) of Salmonella typhimurium and resistance to pulsed electric field (PEF) inactivation, as well as the expression of stress-related genes and fatty acid biosynthesis-associated genes were investigated. Results indicated that the PEF resistance of S. typhimurium increased as growth temperature increased. S. typhimurium cultivated at 10 °C exhibited the lowest PEF resistance with the reduction of 4.23 log₁₀ CFU/mL, while the reduction of 2.10 log₁₀ CFU/mL was found in S. typhimurium cultivated at 45 °C under the same PEF treatment, due to the up-regulation of the expression of fabA gene, which was characterized by the lowest T_m of membrane phospholipids and the greatest membrane fluidity. Although the expression of alternative sigma factors were altered by growth temperature, these genes were not essential for S. typhimurium to develop PEF resistance, suggesting that the PEF resistance modified by growth temperature could be caused by alterations in membrane fluidity.Industrial relevancePulsed electric fields (PEF) treatment has been widely applied in nonthermal pasteurization and increasingly focused on synergistic combinations with other techniques such as thermal treatment, sonication and antibacterial agents to improve the efficacy of PEF to inactivate micro-organisms. Our results indicated that S. typhimurium cultivated at relatively lower temperature was easily inactivated by PEF, due to the up-regulation of the expression of fabA gene, which was characterized by the lowest phase transition temperature of cytoplasmic membrane phospholipids and the greatest membrane fluidity. Therefore, the underlying mechanism of alterations in PEF resistance of S. typhimurium induced by growth temperature was explored to achieve better understanding of microbial inactivation by PEF.     

Antibiotic resistance in bacteria isolated from vegetables with regards to the marketing stage (farm vs. supermarket)

The aim of this study was to elucidate whether and to what extent fresh produce from Germany plays a role as a carrier and reservoir of antibiotic resistant bacteria. For this purpose, 1001 vegetables (fruit, root, bulbous vegetables, salads and cereals) were collected from 13 farms and 11 supermarkets in Germany and examined bacteriologically. Phenotypic resistance of Enterobacter cloacae (n = 172); Enterobacter gergoviae (n = 92); Pantoea agglomerans (n = 96); Pseudomonas aeruginosa (n = 295); Pseudomonas putida (n = 106) and Enterococcus faecalis (n = 100) against up to 30 antibiotics was determined by using the microdilution method. Resistance to ß-lactams was most frequently expressed by P. agglomerans and E. gergoviae against cefaclor (41% and 29%). Relatively high resistance rates were also observed for doxycycline (23%), erythromycin (21%) and rifampicin (65%) in E. faecalis, for spectinomycin (28%) and mezlocillin (12%) in E. cloacae, as well as for streptomycin (19%) in P. putida. In P. aeruginosa, relatively low resistance rates were observed for the aminoglycosides amikacin, apramicin, gentamicin, neomycin, netilmicin and tobramycin (< 4%); 11% was resistant to streptomycin. No glycopeptide-resistant enterococci were observed. Resistance rates of bacteria isolated from farm samples were higher than those of the retail markets whenever significant differences were observed. This suggests that expressing resistance is at the expense of bacterial viability, since vegetables purchased directly at the farm are probably fresher than at the supermarket, and they have not been exposed to stress factors. However, this should not keep the customer from buying directly at the farm, since the overall resistance rates were not higher than observed in bacteria from human or animal origin. Instead, peeling or washing vegetables before eating them raw is highly recommended, since it reduces not only the risk of contact with pathogens, but also that of ingesting and spreading antibiotic resistant bacteria.     

Antibiotic resistance in food-related bacteria--a result of interfering with the global web of bacterial genetics

A series of antibiotic resistance genes have been sequenced and found to be identical or nearly identical in various ecological environments. Similarly, genetic vectors responsible for assembly and mobility of antibiotic resistance genes, such as transposons, integrons and R plasmids of similar or identical type are also widespread in various niches of the environment. Many zoonotic bacteria carry antibiotic resistance genes directly from different food-producing environments to the human being. These circumstances may have a major impact on the degree for success in treating infectious diseases in man. Several recent examples demonstrate that use of antibiotics in all parts of the food production chain contributes to the increasing level of antibiotic resistance among the food-borne pathogenic bacteria. Modern industrialized food production adds extra emphasis on lowering the use of antibiotics in all parts of agriculture, husbandry and fish farming because these food products are distributed to very large numbers of humans compared to more traditional smaller scale niche production.     

Altering the thermal resistance of foodborne bacterial pathogens with an eggshell membrane waste by-product

Eggshells from egg-breaking operations are a significant waste disposal problem. Thus, the development of value-added by-products from this waste would be welcomed by the industry. The ability of extracted eggshell membranes containing, several bacteriolytic enzymes (i.e., lysozyme and beta-N-acetylglucosaminidase) or other membrane components to alter the thermal resistance of gram-positive and gram-negative bacterial pathogens was evaluated. Mid-log phase cells of Salmonella Enteritidis (SE), Salmonella Typhimurium (ST), Escherichia coli O157:H7 (EC), Listeria monocytogenes Scott A (LM), and Staphylococcus aureus (SA) were suspended in 100 ml of 0.1% peptone water (pH 6.9, 10(7-8) CFU/ml) containing either 0 (control) or 10 g of an eggshell membrane extract and incubated at 37 degrees C for 45 min. Following exposure, membrane-free samples (1.5 ml) were heated in a 56 degrees C (LM, SA), 54 degrees C (SE, ST), or 52 degrees C (EC) water bath from 0 to 14 min in sealed glass reaction vials (12 by 32 mm), and the survivors were recovered on brain heart infusion agar. Population reductions ranging from 27.6% (SA) to 99.8% (LM) (ST, 43.8%; SE, 47.5%; EC, 71.8%) were observed for cells treated for 45 min with extracted membrane, as compared to controls. D-value reductions ranging from 0 (LM) to 87.2% (SE) (SA, 36.7%; EC, 83.3%; ST, 86.3%) were observed when membrane-treated cells were subsequently heat inactivated. The effects of exposure pH, time, temperature, and organic load on membrane activity were also evaluated with Salmonella Typhimurium. Exposure pH (5.0 versus 6.9), time (15 versus 45 min), and temperature (4 degrees C versus 37 degrees C) did not significantly reduce the impact of eggshell membranes on D-values. However, the presence of organic matter (0.1% peptone water versus skim milk) significantly reduced the thermal resistance-reducing capacity of the membranes. These preliminary findings provide information on the potential use of extracted eggshell membranes to alter bacterial heat resistance.     

Determination of steroidal hormone profiles along the Jalle d'Eysines River (near Bordeaux, France)

Steroidal estrogens have been shown to be the main contributors to the estrogenic activity observed in aquatic systems contaminated with sewage treatment work effluents. Although the occurrence of steroid hormones in the environment has received a great deal of attention, little is known about their fate in aquatic systems. In the presentwork, concentrations of conjugated and unconjugated hormonal steroids (estrone, 17beta-estradiol, estriol, 17alpha-ethynylestradiol, mestranol, progesterone, norethindrone, and D-norgestrel) were determined in the effluent of the Eysines sewage treatment plant (near Bordeaux, France), and along the receiving river, the Jalle d'Eysines River. Sampling was undertaken in summer and in winter conditions, to study both the temporal and the spatial distributions of steroids in this river. Only unconjugated natural estrogens were detected in the effluent. Estrone was the dominant compound (detected in all effluent samples, 17.1-71.0 ng x L(-1)), while estradiol and its metabolite estriol were detected only once, at much lower levels (4.4 and 2.9 ng x L(-1), respectively). Levels of estrogens were clearly raised above the detection limits downstream of the Eysines STP effluent discharge. Seasonal variations of estrone degradation rates were observed. In summer, the apparent decay rates of estrogen levels exceeded that of dilution, indicating high removal rates from the water column: 50% of the initial amount of this steroid was degraded within 1.7 km downstream of the effluent discharge. In winter, however, estrone levels did not significantly decrease over a 10 km reach downstream of the effluent discharge (1.9-1.8 ng x L(-1)). Steroids were determined in the particulate material of the river, but levels were below the detection limits (0.4-1.9 ng x g(-1)), indicating that sorption was not a major sink of estrogens. Therefore, it is likely that biodegradation plays a major role in the removal of steroids from the river and the different decay rates are probably related to differences in bacterial activity within the river.     

浅谈制浆漂白废水深度处理技术

近年来,造纸行业对环境造成的污染受到越来越多的关注,如何治理漂白废水,使其不再成为污染源之一,同时力争变废为宝,使其再利用,是当前很多研究人员的主要课题之一,本文主要从物理化学法、生物法、膜分离技术和超滤技术法的角度,探讨了治理漂白废水的处理技术.     

Antibiotic resistance and tolerance to simulated gastrointestinal conditions of eight hemolytic Bacillus pumilus isolated from pulque,a traditional Mexican beverage

Food Science and Biotechnology - Traditional fermented sap beverages from two provinces of Mexico were studied for the isolation of pathogenic bacteria from these beverages. Eight strains of...     

Antibiotic resistance in gut bacteria from dairy calves: a dose response to the level of antibiotics fed in milk

Dairy calves are commonly fed milk from cows treated with antibiotics. The concentration of beta-lactam antibiotic residues found in milk from treated cows was used to determine the range of concentrations of penicillin used in a dose-regulated experiment. Thirty-one Holstein calves were randomly assigned to milk with penicillin G added at concentrations of 0, 6.25, 12.5, 25, and 50 microl/kg. Fecal swabs were taken from each calf twice weekly. Resistance to penicillin was tested by measuring the zone of inhibition in bacterial growth around a disk impregnated with the antibiotic. Inhibition was greatest for bacteria from calves fed milk with no penicillin (2.89 +/- 0.14 mm), and declined as the penicillin dose provided in the milk increased (to a low of 0.70 +/- 0.10 for the 50 microl/kg treatment group). In conclusion, resistance of gut bacteria to antibiotics increases with increasing concentrations of penicillin in the milk fed to dairy calves.     

Polymorphisms in the bovine leptin gene associated with perinatal mortality in Holstein-Friesian heifers

Leptin is an important regulator of fetal and placental growth. This study evaluated the association of single nucleotide polymorphisms (SNP) in the leptin gene with perinatal mortality (stillbirths and mortality within 24 h of parturition) in 385 Holstein-Friesian heifers on 18 dairy farms in the United Kingdom. The 3 SNP evaluated were exon 2FB, UASMS1, and UASMS2. The mean age at first calving was 27.0 ± 0.2 mo. Associations between each SNP and perinatal mortality (calf alive or dead) were tested using a generalized linear model that included herd-year-season, calf sex, age at first calving, and age and pedigree of the dam. The overall level of perinatal mortality in the population was 16.9%, with significant allelic substitution effects for exon 2FB and UASMS1. These 2 SNP were in close linkage disequilibrium with each other (r² = 0.98) but not with UASMS2 (r² = 0.10). For exon 2FB, perinatal mortality was similar between heifers carrying the CT and TT alleles (20%), but was higher than in heifers carrying the CC allele (11%). For UASMS1, mortality was 21% with the CC and CT alleles but only 10% with the TT allele. No associations of perinatal mortality with SNP were found in the UASMS2 data set, possibly influenced by the low frequency (2%) of the TT genotype. No significant effects of herd-year-season, age at first calving, or calf sex were found. In conclusion, polymorphisms in the leptin gene were associated with 2-fold differences in perinatal mortality in dairy heifers.     

Atmospheric deposition of V,Cr, and Ni since the late glacial: effects of climatic cycles,human impacts,and comparison with crustal abundances

Vanadium, Cr, and Ni accumulating in a Swiss peat bog since 12 370 14C yr B.P. have been measured using inductively coupled plasma-mass spectrometry (ICP-MS) after acid dissolution in a microwave autoclave. Strict quality control schemes were applied to guarantee the accuracy of the applied analytical methodology. The concentration gradients in the peat column and comparison with Pb indicate that V, Cr, and Ni are effectively immobile in the ombrotrophic section of the peat profile but that Ni is added to the minerotrophic peat layers by chemical weathering of the underlying sediments. The lowest metal concentrations were found during the Holocene climate optimum (5320-8230 14C yr B.P.) when "natural background" values averaged 0.55 +/- 0.13 microg g(-1) V, 0.76 +/- 0.17 microg g(-1) Cr, and 0.46 +/- 0.09 microg g(-1) Ni (n = 18); given the average bulk density (0.05 g/cm3) and accumulation rate (0.05 cm/ yr) of peat in this zone, the corresponding atmospheric fluxes are approximately 14, 19, and 12 microg m(-2) yr(-1) for V, Cr, and Ni, respectively. The highest concentrations of V, Cr, and Ni were found during the Younger Dryas cold climate event (centered at 10 590 14C yr B.P.) when background values were exceeded by about 40 times. Elevated concentrations and accumulation rates were also found at 8230 and 5320 14C yr B.P., which are consistent with the elevated dust fluxes recorded by Greenland ice cores. By far the greatest contribution of the three elements to the peat inventory is atmospheric soil dust, and the metal fluxes vary not only with climate change but also land-use history (especially the beginning of forest clearing for agriculture ca. 6 millennia ago). The V/Sc, Cr/Sc, and Ni/ Sc ratios were remarkably similar to their corresponding ratios in the earth's crust until the onset of the Industrial Revolution (240 14C yr B.P.), which largely validates the use of crustal concentrations for calculating enrichment factors (EF) for these elements. In modern samples, the EFs of V, Cr, and Ni reach maximum values between 2.4 and 4.1, relative to background; anthropogenic emissions are a more likely explanation of the elevated EFs than either plant uptake or chemical diagenesis. This study demonstrates the usefulness of peat bogs as archives of atmospheric metal deposition and underpins the potential of peat cores to help distinguish between lithogenic and anthropogenic metal sources.     

Inhalation cancer risk associated with exposure to complex polycyclic aromatic hydrocarbon mixtures in an electronic waste and urban area in South china

Atmospheric particulate matter samples were collected from May 2010 to April 2011 in a rural e-waste area and in Guangzhou, South China, to estimate the lifetime inhalation cancer risk from exposure to parent polycyclic aromatic hydrocarbons (PAHs), high molecular weight PAHs (MW 302 PAHs), and halogenated PAHs (HPAHs). Seasonal variations in the PAH concentrations and profiles within and between the e-waste and urban areas indicated different PAH sources in the two areas. Benzo[b]fluoranthene, benzo[a]pyrene, dibenz[ah]anthracene, and dibenzo[al]pyrene made the most significant contribution to the inhalation cancer risk. MW 302 PAHs accounted for 18.0% of the total cancer risk in the e-waste area and 13.6% in the urban area, while HPAHs made a minor contribution (<0.1%) in both the areas. The number of lifetime excess lung cancers due to exposure to parent PAHs, MW 302 PAHs, and HPAHs ranged from 15.1 to 1198 per million people in the e-waste area and from 9.3 to 737 per million people in Guangzhou. PAH exposure accounted for 0.02 to 1.94% of the total lung cancer cases in Guangzhou. On average, the inhalation cancer risk in the e-waste area was 1.6 times higher than in the urban area. The e-waste dismantling activities in South China led to higher inhalation cancer risk due to PAH exposure than the urban area.     

酒糟滤液回用技术在酒精生产中的应用研究

酒精糟液中含有大量可供酵母吸收利用的物质,经过滤处理后的上清液可以回用至酒精生产.该文以河南省某发酵酒精生产企业酒精生产线为例,通过对影响酒精糟液回用的因素进行分析,确定了最佳回流比和新鲜水添加比例,当回流比为50％,过滤液与清水的比值在1∶2.33左右时,发酵效果最好,提高了酒精糟液的回收利用率.酒精糟滤液回用技术的实施,将减少污染、合理利用资源、实现经济效益和环境效益相统一.     

Characterization of Listeria monocytogenes isolates from lactating dairy cows in a Wisconsin farm: Antibiotic resistance,mammalian cell infection,and effects on the fecal microbiota

Listeria monocytogenes is an invasive foodborne pathogen that is ubiquitously present in the dairy farm environment. Although cattle are a reservoir of L. monocytogenes, most adult animals do not exhibit clinical symptoms, suggesting a homeostasis between this pathogen and the bovine gastrointestinal ecosystem. Nevertheless, substantial prevalence of L. monocytogenes fecal shedding by dairy cattle has been reported in many studies, posing threats of transmission within the herd and contamination of the human food supply. Accordingly, understanding the L. monocytogenes ecology within the bovine gastrointestinal tract is important to prevent clinical illness in the animal host, reduce transmission, and guide intervention strategies. In this study, we conducted a longitudinal sampling of fecal samples from 20 lactating dairy cows in one Wisconsin farm over a 29-d period and found a strikingly high incidence of L. monocytogenes shedding, in 90% of sampled animals. The L. monocytogenes isolates were genetically diverse, representing all common serotypes previously identified from cattle. Additionally, most tested isolates were resistant to ampicillin, and a few were also resistant to gentamicin or trimethoprim/sulfamethoxazole. Most isolates effectively infected human epithelial cells (Caco-2) and murine fibroblasts (L2), suggesting that they are all capable of causing systemic infection if the intestinal barrier is breached. Finally, we investigated the effects of L. monocytogenes colonization on the gastrointestinal tract microbiota by analyzing the fecal bacterial communities of some shedding and nonshedding cows. Whereas L. monocytogenes did not affect the α and β diversity of tested animals, a subset of shedding cows exhibited different abundances of certain operational taxonomic units within the Bacteroidetes and Firmicutes phyla compared with nonshedding cows. Overall, our findings highlight the threat of antibiotic resistance among some L. monocytogenes isolates, emphasize the need for a strain-specific approach in listeriosis treatment, and suggest the potential negative influence of subclinical L. monocytogenes carriage on animal gut health.