Richard ssell Agricultural Research Center
Richard ssell Agricultural Research Center
Pedroso A.A.,University of Georgia |
Hurley-Bacon A.L.,Merial |
Zedek A.S.,Zoetis Animal Health |
Kwan T.W.,University of Georgia |
And 7 more authors.
International Journal of Environmental Research and Public Health | Year: 2013
Food animal production systems have become more consolidated and integrated, producing large, concentrated animal populations and significant amounts of fecal waste. Increasing use of manure and litter as a more "natural" and affordable source of fertilizer may be contributing to contamination of fruits and vegetables with foodborne pathogens. In addition, human and animal manure have been identified as a significant source of antibiotic resistance genes thereby serving as a disseminator of resistance to soil and waterways. Therefore, identifying methods to remediate human and animal waste is critical in developing strategies to improve food safety and minimize the dissemination of antibiotic resistant bacteria. In this study, we sought to determine whether withdrawing antibiotic growth promoters or using alternatives to antibiotics would reduce the abundance of antibiotic resistance genes or prevalence of pathogens in poultry litter. Terminal restriction fragment length polymorphism (T-RFLP) paired with high throughput sequencing was used to evaluate the bacterial community composition of litter from broiler chickens that were treated with streptogramin growth-promoting antibiotics, probiotics, or prebiotics. The prevalence of resistance genes and pathogens was determined from sequencing results or PCR screens of litter community DNA. Streptogramin antibiotic usage did not elicit statistically significant differences in Shannon diversity indices or correlation coefficients among the flocks. However, T-RFLP revealed that there were inter-farm differences in the litter composition that was independent of antibiotic usage. The litter from all farms, regardless of antibiotic usage, contained streptogramin resistance genes (vatA, vatB, and vatE), macrolide-lincosamide-streptogramin B resistance genes (ermA and ermB), the tetracycline resistance gene tetM and class 1 integrons. There was inter-farm variability in the distribution of vatA and vatE with no statistically significant differences with regards to usage. Bacterial diversity was higher in litter when probiotics or prebiotics were administered to flocks but as the litter aged, diversity decreased. No statistically signficant differences were detected in the abundance of class 1 integrons where 3%-5% of the community was estimated to harbor a copy. Abundance of pathogenic Clostridium species increased in aging litter despite the treatment while the abundance of tetracycline-resistant coliforms was unaffected by treatment. However some treatments decreased the prevalence of Salmonella. These findings suggest that withdrawing antibiotics or administering alternatives to antibiotics can change the litter bacterial community and reduce the prevalence of some pathogenic bacteria, but may not immediately impact the prevalence of antibiotic resistance. © 2013 by the authors; licensee MDPI, Basel, Switzerland.
Chen C.-Y.,U.S. Department of Agriculture |
Lindsey R.L.,Richard ssell Agricultural Research Center |
Strobaugh Jr. T.P.,U.S. Department of Agriculture |
Frye J.G.,Richard ssell Agricultural Research Center |
Meinersmann R.J.,Richard ssell Agricultural Research Center
Applied and Environmental Microbiology | Year: 2010
Multi-antimicrobial-resistant Salmonella enterica strains frequently carry resistance genes on plasmids. Recent studies focus heavily on large conjugative plasmids, and the role that small plasmids play in resistance gene transfer is largely unknown. To expand our previous studies in assessing the prevalence of the isolates harboring ColE1-like plasmids carrying the aph gene responsible for kanamycin resistance (Kanr) phenotypes, 102 Kan r Salmonella isolates collected through the National Antimicrobial Resistance Monitoring System (NARMS) in 2005 were screened by PCR using ColE1 primer sets. Thirty isolates were found to be positive for ColE1-like replicon. Plasmids from 23 isolates were able to propagate in Escherichia coli and were subjected to further characterization. Restriction mapping revealed three major plasmid groups found in three or more isolates, with each group consisting of two to three subtypes. The aph genes from the Kanr Salmonella isolates were amplified by PCR, sequenced, and showed four different aph(3')-I genes. The distribution of the ColE1 plasmid groups in association with the aph gene, Salmonella serovar, and isolate source demonstrated a strong linkage of the plasmid with S. enterica serovar Typhimurium DT104. Due to their high copy number and mobility, the ColE1-like plasmids may play a critical role in transmissionof antibiotic resistance genes among enteric pathogens, and these findings warrant a close monitoring of this plasmid incompatibility group. © 2010, American Society for Microbiology.
Akinosho H.,Georgia Institute of Technology |
Hawkins S.,Richard ssell Agricultural Research Center |
Wicker L.,University of Georgia |
Wicker L.,Korea University
Carbohydrate Polymers | Year: 2013
The methyl and hydroxypropyl substituents in hydroxypropyl methylcellulose (HPMC) affect the resulting gel properties. These substituents in five HPMC gels were characterized using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, small-amplitude oscillatory shear measurements, and differential scanning calorimetry (DSC). In FT-IR spectra, the most intense peak appeared at 1053 cm-1, denoting the presence of the glucose ring. The ratio of peak intensities at 1452 cm-1, which represents C H absorptions, and at 1053 cm-1 (I1452/I1053) and percent methylation from gas chromatography exhibited a linear association (r 2 = 0.6296). The broadening of the Raman spectra indicated that the relative crystallinity of HPMC decreases with increasing hydroxypropyl contents. DSC showed no linear relationship between the percent hydroxypropylation in HPMC and the percentage of free water in an HPMC gel. Small-amplitude oscillatory shear measurements revealed that the formation of an entanglements networks and/or weak gel depends on substituent contents. © 2013 Elsevier Ltd. All rights reserved.
Karnik D.,University of Georgia |
Jung J.,University of Georgia |
Jung J.,Sunchon National University |
Hawking S.,Richard ssell Agricultural Research Center |
And 2 more authors.
Food Hydrocolloids | Year: 2016
Isopropanol was used to sequentially precipitate sugar beet pectin (SBP) and generate six fractions that varied in galacturonic acid, protein, ferulic acid and other physic-chemical characteristics. Protein was high in Fractions 1 and 2 at 209 and 154 μg/mg alcohol insoluble solids (AIS), respectively. Fractions 3, 4, and 5 had lower protein values of 77-106 μg/mg AIS; the protein content was 87 μg/mg AIS in unfractionated control. Ferulic acid content in Fraction 1 was 93 μg/mg AIS and at least three times higher than measured in other fractions. The degree of esterification in Fraction 1 was 11% and ranged from 46 to 74% in later precipitating fractions. The relative fluorescence with an external probe for hydrophobicity ranged from 159 to 254 in F1, F2 and F3 compared to negligible values in later fractions. The ζ-potential ranged from -25 to -33 mV and was not different between fractions or control. Molecular weight analysis indicated highly heterogenous pectin (Mw/Mn greater than 2.5) with MW values of 398,630, 543,900, and 442,330 g/mol for F1, F4 and control, respectively. FTIR analysis confirmed that F1 and F2 were richer in protein. SBP that precipitated at the lowest isopropanol addition had the greatest protein, ferulic acid content, particle size, relative fluorescence intensity and lowest uronic acid content and degree of esterification. The type and/or nature of protein in F1 and F4 is likely different. Isopropanol fractionation resulted in SBP fractions with unique physico-chemical properties. © 2016 Published by Elsevier Ltd.
Lewis M.A.,Richard ssell Agricultural Research Center |
Trabelsi S.,Richard ssell Agricultural Research Center |
Nelson S.O.,Richard ssell Agricultural Research Center
Applied Engineering in Agriculture | Year: 2014
The present-day peanut drying process lacks the capability of in-situ kernel moisture content determination in real-time. Samples of peanut pods have to be taken from the drying trailer, cleaned and shelled by an operator to test for the kernel moisture content. The frequency with which the operator samples the peanuts in the drying trailer to determine kernel moisture content determines the accuracy of the drying process in reaching the targeted kernel moisture content. However, by using a microwave moisture meter, developed within USDA ARS and operating at power levels of a few milliwatts, the moisture content of the peanut kernel can be determined without having to shell the peanut pods. An automated quarter-scale drying system, equipped with the microwave meter, was developed and tested, and it has demonstrated effective control of the drying process and accurate real-time monitoring of kernel moisture content. The objective of this study was to evaluate the performance of the drying system with varying initial kernel moisture contents and atmospheric conditions. Therefore, three trials were run where such conditions were varied. Analysis of variance was performed, and standard errors of prediction were evaluated to compare the kernel moisture content values predicted by the microwave moisture meter to those determined by the oven method. In-shell kernel moisture content was determined in real-time with a standard error of performance ≤ 0.55% moisture when compared to the reference oven-drying method. Overall evaluation demonstrated that the automated drying system is an effective solution for user-independent dryer control and real-time, in-shell kernel moisture content monitoring.