Research Note: Evaluation of several inoculation procedures for colonization of day-old broiler chicks with Salmonella Heidelberg.

Before starting a study with many birds, it helps to know the method of chick inoculation. The objective was to compare 3 methods of Salmonella challenge (oral gavage [OR], intracloacal inoculation [IC], and seeder bird [SB]). Day-old broiler chicks (n = 100) were inoculated with 106 colony forming units (CFU) per chick of a marker strain of Salmonella Heidelberg (SH) with each route of inoculation. Chicks (n = 25) inoculated by each route were placed in floor pens on fresh pine shavings litter. For the seeder batch, 5 colonized chicks, each orally gavaged with 106 CFUs, were placed with 20 pen mates. Two weeks after inoculation, 10 birds from each pen and the 5 inoculated seeder birds were euthanized, the ceca were aseptically removed and macerated with a rubber mallet and weighed, and 3 times (w/v) buffered peptone was added and stomached for 60 s. Serial dilutions were made and plated onto Brilliant Green Sulfa plates containing 200 ppm nalidixic acid. Plates were incubated along with the stomached ceca for 24 h at 37°C. If no colonies appeared on the plates, an additional plate was streaked from the preenriched bag and incubated for 24 h at 37°C. In addition to all seeder birds being positive, the number of SH-positive birds out of 20 sampled in each group was 13, 17, and 7 for OR, IC, and SB, respectively. The level of SH per g of ceca and cecal contents was log (SE) 3.0 (0.7), 2.0 (0.4), and 2.6 (0.4) for OR, IC, and SB, respectively. After enrichment, the number of colonized birds out of 20 was 18, 20, and 10 for OR, IC, and SB, respectively. In conclusion, this study suggests that IC is the method to use to ensure most of the challenged birds are colonized. However, if you prefer to have a smaller percentage of the birds colonized with higher levels, then OR might be better.

One Health and antimicrobial resistance, a United States perspective.

Antimicrobial drugs are a precious resource, responsible for saving millions of lives since their discovery. Unfortunately, some antimicrobials are rapidly losing their effectiveness due to the development and spread of antimicrobial resistance (AMR), a multi-faceted and complex problem affecting humans, animals, plants and the environment. While AMR is a global problem, in this paper, the authors briefly highlight some ongoing efforts in the United States of America aimed at integrating a One Health approach into policies and programmes that address this important health threat.

Les antibiotiques sont des ressources de grande valeur qui ont sauvé des millions de vies depuis leur découverte. Malheureusement, certains agents antimicrobiens perdent rapidement leur efficacité en raison de l'apparition et propagation des résistances à ces agents, phénomène complexe et multidimensionnel qui affecte l'homme, les animaux, les plantes et l'environnement. La résistance aux agents antimicrobiens est un problème mondial ; dans cet article, les auteurs décrivent certaines initiatives actuellement mises en oeuvre aux États-Unis d'Amérique pour intégrer l'approche Une seule santé dans les politiques et les programmes conçus pour lutter contre cette menace sanitaire majeure.

Los fármacos antimicrobianos son un recurso valiosísimo, cuyo uso ha salvado millones de vidas desde que fueron descubiertos. Lamentablemente, algunos de ellos están perdiendo rápidamente eficacia debido a la aparición y propagación de resistencias, lo que plantea un problema tan complejo como poliédrico, que afecta a personas, animales, plantas y ecosistemas. Aunque la dimensión del problema es planetaria, los autores destacan aquí brevemente algunas de las iniciativas en curso en los Estados Unidos de América que tienen por objetivo integrar los planteamientos de Una sola salud en el conjunto de políticas y programas desde los cuales se aborda esta importante amenaza sanitaria.

Managing Beef Backgrounding Residual Soil Contaminants by Alum and Biochar Amendments.

Heavy manure-derived contamination of soils can make animal congregating areas nonpoint sources for environmental pollution. In situ soil stabilization is a cost-effective management strategy with a focus on lowering contaminant availability and limiting release to the environment. Soil stabilizing amendments can help mitigate the negative environmental impacts of contaminated soils. In this 2-yr study, we examined the effects of adding no amendment (control) or treating with alum [Al (SO)⋅18HO] or biochar as soil amendments on Mehlich-3 extractable soil P, Cu, and Zn contents, antimicrobial monensin concentrations, total bacteria (16S ribosomal RNA [rRNA] gene), antibiotic resistance genes (1 and B), and Class 1 integrons (1) in an abandoned beef backgrounding setting. The alum reduced soil P (1374 to 1060 mg kg), Cu (7.7 to 3.2 mg kg), and Zn (52.4 to 19.6 mg kg) contents. Both alum and biochar reduced monesin concentrations (1.8 to 0.7 and 2.1 to 1.1 ng g, respectively). All the treatments harbored consistent 16 rRNA concentrations (10 copies g) throughout. The B gene concentration (10 copies g) was lower than either the 1 or the 1 genes (10 copies g), regardless of treatments. However, concentrations of all genes in the soils of animal congregation areas were higher than those in background soils with the least animal impact. In contrast with the effect on other contaminants, the effect of soil amendments on bacteria with antibiotic resistance genes was not biologically significant. Future research should be directed toward evaluating effective alternative methods to mitigate these bacterial populations.

Management Practices Affect Soil Nutrients and Bacterial Populations in Backgrounding Beef Feedlot.

Contaminants associated with manure in animal production sites are of significant concern. Unless properly managed, manure-derived soil nutrients in livestock production sites can deteriorate soil and water quality. This 3-yr study evaluated a soil nutrient management strategy with four sequentially imposed management practices: 12-mo backgrounding (BG), manure removal from the feeder area (FD), 12-mo destocking (DS), and 12-mo grass hay harvesting (H) in a small backgrounding feedlot. Resulting soil nutrient levels, total (), and N cycling bacterial ( and ) populations after each management practice in feedlot feeder and grazing (GR) areas and in crop grown at the control location (CT) were measured. Irrespective of management practice, FD contained greater soil nutrient concentrations than the GR and CT. Regardless of management practice, total bacteria cells (1.4 × 10 cells g soil) and nitrate reducers (5.2 × 10 cells g soil) were an order of magnitude higher in the FD than in the GR and CT, whereas nitrifying bacteria concentrations (1.4 × 10 cells g soil) were higher in the GR. Manure removal from the feeder area reduced M3-P (39%), total C (21%), total N (23%), NH-N (47%), and NO-N (93%) levels established in the FD during BG. Destocking lowered total C and N (45%) in the FD and NH-N (47%), NO-N (76%), and Zn (16%) in the GR. Hay harvesting reduced all soil nutrients in the FD and GR marginally. The management strategy has potential to lower soil nutrient concentrations, control soil nutrient buildup, and limit nutrient spread within the feedlot.

Effect of turning frequency and season on composting materials from swine high-rise facilities.

Composting swine slurries has several advantages, liquid slurries are converted to solids at lower moisture, the total volume and weight of material is reduced and the stabilized product is more easily transported off-site. Despite this, swine waste is generally stored, treated and applied in its liquid form. High-rise finishing facilities (HRFF) permit liquid slurries to be converted to solids which are partially decomposed underneath the HRFF and then finished in compost windrows. The purpose of this study was to evaluate the effect of turning frequency and ambient weather conditions on biological, physical and chemical properties of composted slurry-woodchip mixtures from HRFF. Compost trials were conducted in either fall (FT) or spring (ST) and piles were turned once or three times per week or upon compost temperature reaching 65°C. Physical, chemical and microbiological characteristics were measured over the course of 112 (FT) or 143 (ST) days of composting. Total carbon, total nitrogen (N) and inorganic N decreased in all piles. Ammonium decreased while nitrate increased in all piles (including unturned), but total N losses were greatest in piles turned more frequently during the ST. Microbial populations of nitrifiers were dominated by ammonia-oxidizing archaea (3.0×10(3)-4.2×10(6)cellsg(-1) compost) but ammonia oxidizing bacteria (below detection to 6.0×10(5)cellsg(-1) compost) varied in response to turning and compost temperature; denitrifiers were present in high concentrations throughout the process. Swine HRFF materials composted well in windrows regardless of turning frequency and despite significant differences in starting materials and low initial C/N. Volume reduction, low moisture and low readily degradable organic matter suggest that the finished compost would have lower transportation costs and should provide value as a soil conditioner.

Short communication: Milk fat depression induced by conjugated linoleic acid and a high-oil and low-fiber diet occurs equally across the day in Holstein cows.

Recently, a circadian rhythm of milk and milk component synthesis has been characterized that is partially dependent on the timing of feed intake. Our objective was to determine if inhibition of milk fat synthesis during diet-induced milk fat depression occurred to a higher degree during certain phases of the day. A retrospective analysis was conducted on 2 experiments that induced milk fat depression while milking cows 3 times per day at equal intervals. The response at each milking was analyzed using mixed model ANOVA with repeated measures. In experiment 1, nine multiparous Holstein cows were arranged in a 3×3 Latin square design, and treatments were control, 3-d intravenous infusion of 10 g/d of trans-10,cis-12 conjugated linoleic acid (CLA), and a low-forage and high-fat diet for 10 d. In experiment 2, ten multiparous ruminally cannulated cows were arranged in a replicated design and milk samples were collected during a control period or after 5 d of abomasal infusion of 10 g/d of CLA. The daily pattern of milk fat concentration and yield did not differ between treatments in either experiment. In experiment 1, an effect was found of treatment and milking time on milk fat concentration and yield. Similarly, in experiment 2, main effects were found of treatment and milking time on milk fat concentration and an effect of treatment, but no effect of milking time on milk fat yield. Milk fat percent was increased from 3.41 to 4.06% and 3.25 to 3.48% from the morning to the afternoon milking in experiments 1 and 2, respectively. Additionally, milk fatty acid profile, including trans intermediates, was changed over the day in experiment 1, but the magnitude of the changes were small and the pattern did not differ among treatments. A daily rhythm of milk fat concentration and yield was observed in cows milked 3 times a day, but milk fat depression decreases milk fat yield equally over the day.

Detection of pathogens, indicators, and antibiotic resistance genes after land application of poultry litter.

Poultry litter (PL) is a by-product of broiler production. Most PL is land applied. Land-applied PL is a valuable nutrient source for crop production but can also be a route of environmental contamination with manure-borne bacteria. The objective of this study was to characterize the fate of pathogens, fecal indicator bacteria (FIB), and bacteria containing antibiotic resistance genes (ARGs) after application of PL to soils under conventional till or no-till management. This 2-yr study was conducted in accordance with normal agricultural practices, and microbial populations were quantified using a combination of culture and quantitative, real-time polymerase chain reaction analysis. Initial concentrations of in PL were 5.4 ± 3.2 × 10 cells g PL; sp. was not detected in the PL but was enriched periodically from PL-amended soils. was detected in PL (1.5 ± 1.3 × 10 culturable or 1.5 ± 0.3 × 10 genes g) but was rarely detected in field soils, whereas enterococci (1.5 ± 0.5 × 10 cells g PL) were detected throughout the study. These results suggest that enterococci may be better FIB for field-applied PL. Concentrations of ARGs for sulfonamide, streptomycin, and tetracycline resistance increased up to 3.0 orders of magnitude after PL application and remained above background for up to 148 d. These data provide new knowledge about important microbial FIB, pathogens, and ARGs associated with PL application under realistic field-based conditions.

Soil Nutrients, Bacteria Populations, and Veterinary Pharmaceuticals across a Backgrounding Beef Feedlot.

Beef cattle backgrounding operations that grow out weaned calves for feedlot finishing contain several environmentally significant constituents. A better understanding of these constituents and their environmental distribution will aid in the development of effective management guidelines for sustainable beef production. This research investigated soil nutrients, bacterial, and veterinary pharmaceutical concentrations across a small backgrounding beef feedlot on a karst landscape. Results indicated that all contaminants were highly concentrated in the feeder area (FD) and were lower in the other feedlot areas. The FD soils had a pH of 8.2, 59 mg kg soil organic matter (SOM), 2002 mg kg soil test phosphorus (STP), 99.7 mg kg NH-N, and 18.3 mg kg NO-N. The other locations were acidic (5.9-6.9 pH) and contained 39 mg kg SOM, 273 mg kg STP, 21.5 mg kg NH-N, and 2.0 NO-N mg kg. Bacteria populations in the FD averaged 2.7 × 10 total cells, 3.9 × 10 spp., 2.9 × 10 spp, and 4.5 × 10 cells per gram of soil. spp. and spp. concentrations were 1 to 4 orders of magnitude lower at the other locations. showed lower dynamic range and was generally uniformly distributed across the landscape. Antibiotic and parasiticide concentrations in the FD were 86.9 ng g monensin, 25.0 ng g lasalocid, and 10.3 ng g doramectin. Their concentrations were 6- to 27-fold lower in the other feedlot locations. Contaminant management plans for this small feedlot will therefore focus on the feeder and nearby grazing areas where soil nutrients, bacteria populations, and veterinary pharmaceuticals were most concentrated.

Sensitivity of Mycobacterium avium subsp paratuberculosis, Escherichia coli and Salmonella enterica serotype Typhimurium to low pH, high organic acids and ensiling.

AIMS: To evaluate the persistence of Mycobacterium avium subsp paratuberculosis (Myco. paratuberculosis), Salmonella enterica serotype Typhimurium (Salm.Typhimurium) and a commensal Escherichia coli (E. coli) isolate under the low pH and high organic acid (OA) conditions of ensiling of forages. METHODS AND RESULTS: Decay rates and the time required to obtain a 90% reduction in cell concentration were calculated following (i) exposure to buffered OA (pH 4.0, 5.0, 6.0 or 7.0) (ii) exposure to silage exudates and (iii) survival through ensiling of forage materials. Salm. Typhimurium had higher decay rates in silage exudates (-0.5601 day(-1) ) than did E. coli (-0.1265 day(-1) ), but both exhibited lower decay rates in silage than in OA or silage exudates. Myco. paratuberculosis showed no decrease in silage and decay rates in silage exudates were significantly lower (2-12 times) than for the other two organisms. CONCLUSIONS: Escherichia coli, Salm. Typhimurium and Myco. paratuberculosis exhibit marked differences in response to acidity. All three organisms show acid resistance, but Myco. paratuberculosis in particular, if present in manure and applied to forage grasses, may survive the low pH and high OA of the ensilaging process; silage may therefore be a potential route of infection if ingested by a susceptible animal. SIGNIFICANCE AND IMPACT OF STUDY: This information contributes to the understanding of potential risks associated with silage preservation and contamination of livestock feed with manure-borne pathogens.

Atmospheric emissions of nitrous oxide, methane, and carbon dioxide from different nitrogen fertilizers.

Alternative N fertilizers that produce low greenhouse gas (GHG) emissions from soil are needed to reduce the impacts of agricultural practices on global warming potential (GWP). We quantified and compared growing season fluxes of NO, CH, and CO resulting from applications of different N fertilizer sources, urea (U), urea-ammonium nitrate (UAN), ammonium nitrate (NHNO), poultry litter, and commercially available, enhanced-efficiency N fertilizers as follows: polymer-coated urea (ESN), SuperU, UAN + AgrotainPlus, and poultry litter + AgrotainPlus in a no-till corn ( L.) production system. Greenhouse gas fluxes were measured during two growing seasons using static, vented chambers. The ESN delayed the NO flux peak by 3 to 4 wk compared with other N sources. No significant differences were observed in NO emissions among the enhanced-efficiency and traditional inorganic N sources, except for ESN in 2009. Cumulative growing season NO emission from poultry litter was significantly greater than from inorganic N sources. The NO loss (2-yr average) as a percentage of N applied ranged from 0.69% for SuperU to 4.5% for poultry litter. The CH-C and CO-C emissions were impacted by environmental factors, such as temperature and moisture, more than the N source. There was no significant difference in corn yield among all N sources in both years. Site specifics and climate conditions may be responsible for the differences among the results of this study and some of the previously published studies. Our results demonstrate that N fertilizer source and climate conditions need consideration when selecting N sources to reduce GHG emissions.

Is there a relationship between clinical presentation, diagnostic and radiographic findings and outcome in horses with osteoarthritis of the small tarsal joints?

REASONS FOR PERFORMING STUDY: Despite the possibility that sound horses may have radiographic signs consistent with osteoarthritis of the small tarsal joints (OA-STJ), a diagnosis of 'bone spavin' as a cause of lameness is often made based only on radiographic examination. OBJECTIVES: To determine whether severity of radiographic change and response to treatment are correlated with the duration and degree of lameness and the response to intraarticular anaesthesia in horses with OA-STJ. METHODS: A retrospective study of all horses that showed a positive response to intra-articular anaesthesia of the STJ was performed. Details of history, clinical presentation and diagnostic findings were recorded. Radiographs of affected tarsi were evaluated and scored independently by 2 observers. Follow-up was via a telephone questionnaire with the owner. Statistical analysis was used to assess the association between the duration and degree of lameness, the response to intra-articular anaesthesia and radiographic findings. Response to treatment was compared with the findings from the diagnostic work-up. RESULTS: Ninety-one horses were included (61 unilateral and 30 bilateral lameness). Fifty-nine percent of horses had been lame for over 2 months. There was no association between the duration and degree of lameness, or between duration or degree of lameness, intra-articular anaesthesia and radiographic findings. Response to treatment showed a significant positive association with less severe radiographic changes within the tarsometatarsal (TMT) joint. Follow-up was available for 48% of cases, with 52% horses returning to the same level of exercise. CONCLUSIONS: There is no association between the duration and degree of lameness, the response to intra-articular anaesthesia and radiographic findings in horses with OA-STJ. However, horses that improved following treatment tended to have less marked TMT joint pathology. POTENTIAL RELEVANCE: Response to intra-articular anaesthesia should remain the gold standard for diagnosis of OA-STJ. Predicting which cases are likely to improve following treatment remains difficult.

The transport of Mycobacterium avium subsp. paratuberculosis through saturated aquifer materials.

AIMS: To investigate the processes controlling the transport of Mycobacterium avium subsp. paratuberculosis (Map) through aquifer materials. METHODS AND RESULTS: We measured two important surface characteristics known to affect bacterial attachment to sediment surfaces: surface charge and hydrophobicity. We then measured the transport of Map through laboratory columns packed with aquifer sand with varying ionic strength solutions and sediment surface charge. We found that Map has a strong negative charge and is highly hydrophobic and that the transport of Map through positively charged Fe-coated sands was reduced compared with transport through negatively charged clean quartz sand, although Map transport for all treatments was low compared with the transport behaviour reported in the literature for other bacteria. CONCLUSIONS: Our results suggest that the potential for groundwater contamination by Map is low; however, the organism may remain bound to the soil near the surface where it can be ingested by grazing animals or be released during run off events. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study looking at the surface characteristics and transport behaviour of Map through aquifer materials and therefore provides important information for understanding the movement of Map in the environment.

3-Methylindole production is regulated in Clostridium scatologenes ATCC 25775.

AIMS: 3-Methylindole (3-MI) is a degradation product of L-tryptophan and is both an animal waste malodorant and threat to ruminant health. Culture conditions influencing 3-MI production in Clostridium scatologenes ATCC 25775 were investigated. METHODS AND RESULTS: Extracellular 3-MI levels in cells cultured in brain heart infusion (BHI) medium (pH 7.0) at 33 degrees C and 37 degrees C for 72 h were 907 +/- 38 and 834 +/- 121 micromol l(-1), respectively. Cells cultured in tryptone-yeast (TY) extract medium at 37 degrees C for 48 h produced 104 +/- 86 micromol l(-1) 3-MI; however, addition of 1 mmol l(-1) L-tryptophan failed to increase extracellular levels (113 +/- 50 micromol l(-1) 3-MI). Specific activity of indole acetic acid decarboxylase measured in BHI, TY and TY plus 1 mmol l(-1) tryptophan-grown cells displayed 35-, 33- and 76-fold higher levels than in semi-defined medium-grown cells. CONCLUSIONS: When cultured in rich medium, at 33 degrees C or 37 degrees C and pH 7.0, Cl. scatologenes ATCC 25775 optimally produced 3-MI. Addition of L-tryptophan to medium did not lead to significant increases in extracellular 3-MI levels. Whole cell assays indicate growth in rich medium significantly up-regulated 3-MI production. SIGNIFICANCE AND IMPACT OF THE STUDY: Information presented here may prove useful in understanding what factors influence 3-MI production in malodorous animal wastes.

The effect of alum addition on microbial communities in poultry litter.

Alum [Al(2)(SO(4))(3).14H(2)O] is a common poultry litter amendment used to decrease water-soluble phosphorus or reduce ammonia volatilization, or both. Although the physiochemical effects of alum addition have been well researched, little attention has been given to the poultry litter microbial communities. The goal of this study was to use molecular biological methods [denaturing gradient gel electrophoresis (DGGE), community cloning, and quantitative real-time PCR] to characterize general, group-specific and pathogenic microbial communities in alum (10% wt/wt) and non-alum-treated litter. According to quantitative real-time PCR analyses, alum addition to the poultry litter resulted in significant reductions in both Campylobacter jejuni and Escherichia coli concentrations by the end of the first month of the experiment (3 log and 2 log, respectively). The concentrations of Salmonella spp. were below detection (<5 x 10(3) cell.g(-1) of litter) for the entire experiment. The DGGE analyses revealed significant reductions in the Clostridium/Eubacterium and low %GC gram-positive groups in the alum-treated litters by the end of the first month, with no bands detectable for either group after 8 wk of incubation. Conversely, minimal effects of alum addition were observed in the Actinomycetes community. The most significant shift in the microbial community (based on DGGE analyses) occurred in the fungal population, with a large increase in diversity and abundance within 1 mo of alum addition (1 dominant band on d 0 to 9 dominant bands at 4 wk). Specifically, the incidence of Aspergillus spp. increased from 0 to 50% of the sequences in fungal clone libraries (n = 80) over the course of the experiment. This suggests that the addition of alum to poultry litter potentially shifts the microbial populations from bacterially dominated to dominated by fungi. The ramifications of this shift in dominance are still unknown, and future work will be aimed at characterizing these fungi and elucidating their role in the acidified litter environment.

Development of a quantitative real-time polymerase chain reaction assay to target a novel group of ammonia-producing bacteria found in poultry litter.

Ammonia production in poultry houses has serious implications for flock health and performance, nutrient value of poultry litter, and energy costs for running poultry operations. In poultry litter, the conversion of organic N (uric acid and urea) to NH(4)-N is a microbially mediated process. The urease enzyme is responsible for the final step in the conversion of urea to NH(4)-N. Cloning and analysis of 168 urease sequences from extracted genomic DNA from poultry litter samples revealed the presence of a novel, dominant group of ureolytic microbes (representing 90% of the urease clone library). Specific primers and a probe were designed to target this novel poultry litter urease producer (PLUP) group, and a new quantitative real-time PCR assay was developed. The assay allowed for the detection of 10(2) copies of target urease sequences per PCR reaction (approximately 1 x 10(4) cells per gram of poultry litter), and the reaction was linear over 8 orders of magnitude. Our PLUP group was present only in poultry litter and was not present in environmental samples from diverse agricultural settings. This novel PLUP group represented between 0.1 to 3.1% of the total microbial populations (6.0 x 10(6) to 2.4 x 10(8) PLUP cells per gram of litter) from diverse poultry litter types. The PLUP cell concentrations were directly correlated to the total cell concentrations in the poultry litter and were found to be influenced by the physical parameters of the litters (bedding material, moisture content, pH), as well as the NH(4)-N content of the litters, based on principal component analysis. Chemical parameters (organic N, total N, total C) were not found to be influential in the concentrations of our PLUP group in the diverse poultry litters Future applications of this assay could include determining the efficacy of current NH(4)-N-reducing litter amendments or in designing more efficient treatment protocols.

Survival of Campylobacter jejuni and Escherichia coli in groundwater during prolonged starvation at low temperatures.

AIMS: To evaluate the survival of Campylobacter jejuni relative to that of Escherichia coli in groundwater microcosms varying in nutrient composition. METHODS AND RESULTS: Studies were conducted in groundwater and deionized water incubated for up to 470 days at 4 degrees C. Samples were taken for culturable and total cell counts, nutrient and molecular analysis. Die-off in groundwater microcosms was between 2.5 and 13 times faster for C. jejuni than for E. coli. Campylobacter jejuni had the lowest decay rate and longest culturability in microcosms with higher dissolved organic carbon (4 mg l(-1)). Escherichia coli survival was the greatest when the total dissolved nitrogen (12.0 mg l(-1)) was high. The transition of C. jejuni to the coccoid stage was independent of culturability. CONCLUSION: The differences in the duration of survival and response to water nutrient composition between the two organisms suggest that E. coli may be present in the waters much longer and respond to water composition much differently than C. jejuni. SIGNIFICANCE AND IMPACT OF THE STUDY: The data from these studies would aid in the evaluation of the utility of E. coli as an indicator of C. jejuni. This study also provided new information about the effect of nutrient composition on C. jejuni viability.

Spatial shifts in microbial population structure within poultry litter associated with physicochemical properties.

Microbial populations within poultry litter have been largely ignored with the exception of potential human or livestock pathogens. A better understanding of the community structure and identity of the microbial populations within poultry litter could aid in the development of management practices that would reduce populations responsible for toxic air emissions and pathogen incidence. In this study, poultry litter air and physical properties were correlated to shifts in microbial community structure as analyzed by principal component analysis (PCA) and measured by denaturing gradient gel electrophoresis (DGGE). Litter samples were taken in a 36-point grid pattern at 5 m across and 12 m down a 146 m x 12.8 m chicken house. At each sample point, physical parameters such as litter moisture, pH, air and litter temperature, and relative humidity were recorded, and samples were taken for molecular analysis. The DGGE analysis showed that the banding pattern of samples from the back and water/feeder areas of poultry house were distinct from those of samples from other areas. There were distinct clusters of banding patterns corresponding to the front, middle front, middle back, back, and waterer/feeder areas. The PCA analysis showed similar cluster patterns, but with more distinct separation of the front and midhouse samples. The PCA analysis also showed that moisture content and litter temperature (accounting for 51.5 and 31.5% of the separation of samples, respectively) play a major role in spatial diversity of microbial community in the poultry house. Based on analysis of DGGE fingerprints and cloned DGGE band sequences, there appear to be differences in the types of microorganisms over the length of the house, which correspond to differences in the physical properties of the litter.

Effect of microbial species richness on community stability and community function in a model plant-based wastewater processing system.

Microorganisms will be an integral part of biologically based waste processing systems used for water purification or nutrient recycling on long-term space missions planned by the National Aeronautics and Space Administration. In this study, the function and stability of microbial inocula of different diversities were evaluated after inoculation into plant-based waste processing systems. The microbial inocula were from a constructed community of plant rhizosphere-associated bacteria and a complexity gradient of communities derived from industrial wastewater treatment plant-activated sludge. Community stability and community function were defined as the ability of the community to resist invasion by a competitor (Pseudomonas fluorescens 5RL) and the ability to degrade surfactant, respectively. Carbon source utilization was evaluated by measuring surfactant degradation and through Biolog and BD oxygen biosensor community level physiological profiling. Community profiles were obtained from a 16S-23S rDNA intergenic spacer region array. A wastewater treatment plant-derived community with the greatest species richness was the least susceptible to invasion and was able to degrade surfactant to a greater extent than the other complexity gradient communities. All communities resisted invasion by a competitor to a greater extent than the plant rhizosphere isolate constructed community. However, the constructed community degraded surfactant to a greater extent than any of the other communities and utilized the same number of carbon sources as many of the other communities. These results demonstrate that community function (carbon source utilization) and community stability (resistance to invasion) are a function of the structural composition of the community irrespective of species richness or functional richness.

Treatment of periocular and non-ocular sarcoids in 18 horses by interstitial brachytherapy with iridium-192.

Treatment of the equine sarcoid has posed a significant challenge to clinicians for years and many different methods have been tried with varying success, including ionising radiation. The aim of this study was to review the efficacy of iridium-192 interstitial brachytherapy for the treatment of eight periocular sarcoids and 15 non-ocular sarcoids on 18 horses. All the periocular sarcoids and 13 of the 15 non-ocular sarcoids were treated successfully.

Culturability as an indicator of succession in microbial communities.

Successional theory predicts that opportunistic species with high investment of energy in reproduction and wide niche width will be replaced by equilibrium species with relatively higher investment of energy in maintenance and narrower niche width as communities develop. Since the ability to rapidly grow into a detectable colony on nonselective agar medium could be considered as characteristic of opportunistic types of bacteria, the percentage of culturable cells may be an indicator of successional state in microbial communities. The ratios of culturable cells (colony forming units on R2A agar) to total cells (acridine orange direct microscopic counts) and culturable cells to active cells (reduction of 5-cyano-2,3-ditolyl tetrazolium chloride) were measured over time in two types of laboratory microcosms (the rhizosphere of hydroponically grown wheat and aerobic, continuously stirred tank reactors containing plant biomass) to determine the effectiveness of culturabilty as an index of successional state. The culturable cell:total cell ratio in the rhizosphere decreased from approximately 0.25 to less than 0.05 during the first 30-50 days of plant growth, and from 0.65 to 0.14 during the first 7 days of operation of the bioreactor. The culturable cell:active cell ratio followed similar trends, but the values were consistently greater than the culturable cell:total cell ratio, and even exceeded I in early samples. Follow-up studies used a cultivation-independent method, terminal restriction fragment length polymorphisms (TRFLP) from whole community DNA, to assess community structure. The number of TRFLP peaks increased with time, while the number of culturable types did not, indicating that the general decrease in culturability is associated with a shift in community structure. The ratio of respired to assimilated C-14-labeled amino acids increased with the age of rhizosphere communities, supporting the hypothesis that a shift in resource allocation from growth to maintenance occurs with time. Results from this work indicate that the percentage of culturable cells may be a useful method for assessing the successional state of microbial communities.