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Beltsville, MD, United States

Ingram D.T.,Animal and Natural Resources Institute | Callahan M.T.,Animal and Natural Resources Institute | Ferguson S.,Animal and Natural Resources Institute | Hoover D.G.,University of Delaware | And 6 more authors.
Journal of Applied Microbiology | Year: 2012

Aims: Zero-valent iron (ZVI) filters may provide an efficient method to mitigate the contamination of produce crops through irrigation water. Methods: A field-scale system was utilized to evaluate the effectiveness of a biosand filter (S), a biosand filter with ZVI incorporated (ZVI) and a control (C, no treatment) in decontaminating irrigation water. An inoculum of c.8·5logCFU100ml -1 of Escherichia coli O157:H12 was introduced to all three column treatments in 20-l doses. Filtered waters were subsequently overhead irrigated to 'Tyee' spinach plants. Water, spinach plant and soil samples were obtained on days 0, 1, 4, 6, 8, 10, 13 and 15 and analysed for E. coli O157:H12 populations. Results: ZVI filters inactivated c.6logCFU100ml -1E. coli O157:H12 during filtration on day 0, significantly (P<0·05) more than S filter (0·49CFU100ml -1) when compared to control on day 0 (8·3log CFU100ml -1). On day 0, spinach plants irrigated with ZVI-filtered water had significantly lower E. coli O157 counts (0·13logCFUg -1) than spinach irrigated with either S-filtered (4·37logCFUg -1) or control (5·23logCFUg -1) water. Soils irrigated with ZVI-filtered water contained E. coli O157:H12 populations below the detection limit (2logCFUg -1), while those irrigated with S-filtered water (3·56logCFUg -1) were significantly lower than those irrigated with control (4·64logCFUg -1). Conclusions: ZVI biosand filters were more effective in reducing E. coli O157:H12 populations in irrigation water than sand filters. Significance and Impact of the Study: Zero-valent ion treatment may be a cost-effective mitigation step to help small farmers reduce risk of foodborne E. coli infections associated with contamination of leafy greens. © 2011 No claim to US Government works. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology. Source


Schneider M.J.,Eastern Regional Research Center | Mastovska K.,Eastern Regional Research Center | Solomon M.B.,Beltsville Area Research Center
Journal of Agricultural and Food Chemistry | Year: 2010

The U.S. Food and Drug Administration sets tolerances for veterinary drug residues in muscle but does not specify which type of muscle should be analyzed. To determine if antibiotic residue levels are dependent upon muscle type, seven culled dairy cows were dosed with penicillin G (Pen G) from 1 to 3 days and then sacrificed on day 1, 2, or 5 of withdrawal. A variety (9-15) of muscle samples were collected, along with liver and kidney samples. In addition, corresponding muscle juice samples were prepared. All samples were extracted and analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) to determine Pen G levels. Results showed that Pen G residue levels can vary between and within different muscles, although no reproducible pattern was identified between cows or withdrawal times. Muscle juice appeared to be a promising substitute for muscle as a matrix for screening purposes. Because of the potential for variation within muscles, all samples taken need to be large enough to be representative. © This article not subject to U.S. Copyright. Published 2010 by the American Chemical Society. Source


Andreote A.P.D.,University of Sao Paulo | Rosario M.F.,University of Sao Paulo | Ledur M.C.,Embrapa Suinos e Aves | Jorge E.C.,University of Sao Paulo | And 3 more authors.
Genetics and Molecular Research | Year: 2014

MicroRNAs (miRNAs, miRs) encompass a class of small non-coding RNAs that often negatively regulate gene expression. miRNAs play an essential role in skeletal muscle, determining the proper development and maintenance of this tissue. In comparison to other organs and tissues, the full set of muscle miRNAs and its expression patterns are still poorly understood. In this report, a chicken skeletal muscle miRNA library was constructed, and the expression of selected miRNAs was further characterized during muscle development in chicken lines with distinct muscling phenotypes. Clone library sequence analysis revealed 40 small RNAs with similarities to previously described chicken miRNAs, seven miRNAs that were never identified before in chicken, and some sequence clusters representing other possible novel miRNAs. Temporal expression profiles of three miRNAs associated with cell proliferation and differentiation (miR-125b, miR-221, and miR-206) in two chicken lines (broiler and layer) revealed the differential steady-state levels of these miRs during skeletal muscle growth and suggests that miR-206 is involved in the muscling phenotype that is observed in growth-selected chicken lines. © FUNPEC-RP. Source


Khatibi P.A.,U.S. Department of Agriculture | Roach D.R.,Beltsville Area Research Center | Donovan D.M.,Beltsville Area Research Center | Hughes S.R.,U.S. Department of Agriculture | Bischoff K.M.,U.S. Department of Agriculture
Biotechnology for Biofuels | Year: 2014

Background: One of the challenges facing the fuel ethanol industry is the management of bacterial contamination during fermentation. Lactobacillus species are the predominant contaminants that decrease the profitability of biofuel production by reducing ethanol yields and causing "stuck" fermentations, which incur additional economic losses via expensive antibiotic treatments and disinfection costs. The current use of antibiotic treatments has led to the emergence of drug-resistant bacterial strains, and antibiotic residues in distillers dried grains with solubles (DDGS) are a concern for the feed and food industries. This underscores the need for new, non-antibiotic, eco-friendly mitigation strategies for bacterial contamination. The specific objectives of this work were to (1) express genes encoding bacteriophage lytic enzymes (endolysins) in Saccharomyces cerevisiae, (2) assess the lytic activity of the yeast-expressed enzymes against different species of Lactobacillus that commonly contaminate fuel ethanol fermentations, and (3) test the ability of yeast expressing lytic enzymes to reduce Lactobacillus fermentum during fermentation. Implementing antibiotic-free strategies to reduce fermentation contaminants will enable more cost-effective fuel ethanol production and will impact both producers and consumers in the farm-to-fork continuum. Results: Two genes encoding the lytic enzymes LysA and LysA2 were individually expressed in S. cerevisiae on multi-copy plasmids under the control of a galactose-inducible promoter. The enzymes purified from yeast were lytic against Lactobacillus isolates collected from fermentors at a commercial dry grind ethanol facility including Lactobacillus fermentum, Lactobacillus brevis, and Lactobacillus mucosae. Reductions of L. fermentum in experimentally infected fermentations with yeast expressing LysA or LysA2 ranged from 0.5 log10 colony-forming units per mL (CFU/mL) to 1.8 log10 (CFU/mL) over 72 h and fermentations treated with transformed yeast lysate showed reductions that ranged from 0.9 log10 (CFU/mL) to 3.3 log10 (CFU/mL). Likewise, lactic acid and acetic acid levels were reduced in all experimentally infected fermentations containing transformed yeast (harboring endolysin expressing plasmids) relative to the corresponding fermentations with untransformed yeast. Conclusions: This study demonstrates the feasibility of using yeast expressing bacteriophage endolysins to reduce L. fermentum contamination during fuel ethanol fermentations. © 2014 Khatibi et al.; licensee BioMed Central Ltd. Source


Patel J.R.,Beltsville Area Research Center | Yossa I.,Beltsville Area Research Center | Yossa I.,U.S. Food and Drug Administration | Macarisin D.,Beltsville Area Research Center | And 2 more authors.
Applied and Environmental Microbiology | Year: 2015

This study investigated the effect of a 30-cm covering of finished compost (FC) on survival of Escherichia coli O157:H7 and Salmonella spp. in active static and windrow composting systems. Feedstocks inoculated with E. coli O157:H7 (7.41 log CFU/g) and Salmonella (6.46 log CFU/g) were placed in biosentry tubes (7.5-cm diameter, 30-cm height) at three locations: (i and ii) two opposing sides at the interface between the FC cover layer (where present) and the feedstock material (each positioned approximately 10 cm below the pile's surface) and (iii) an internal location (top) (approximately 30 cm below the surface). On specific sampling days, surviving populations of inoculated E. coli O157:H7 and Salmonella, generic E. coli, and coliforms in compost samples were determined. Salmonella spp. were reduced significantly within 24 h in windrow piles and were below the detection limit after 3 and 7 days at internal locations of windrow and static piles containing FC covering, respectively. Likewise, E. coli O157:H7 was undetectable after 1 day in windrow piles covered with finished compost. Use of FC as a covering layer significantly increased the number of days that temperatures in the windrows remained ≥55°C at all locations and in static piles at internal locations. These time-temperature exposures resulted in rapid reduction of inoculated pathogens, and the rate of bacterial reduction was rapid in windrow piles. The sample location significantly influenced the survival of these pathogens at internal locations compared to that at interface locations of piles. Finished compost covering of compost piles aids in the reduction of pathogens during the composting process. © 2015, American Society for Microbiology. Source

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