Bioaerosol concentrations inside one naturally ventilated and one mechanically ventilated swine finishing barn were assessed by sampling air using membrane filtration and impaction (six-stage Andersen sampler), and assayed by culture method. The barns, located on the same commercial farm in northeast Kansas, did not show any significant difference (p > 0.05) in concentrations of total and respirable airborne microorganisms. The overall mean total concentrations inside the two barns were 6.6 x 10(4) colony forming units (CFU)/m3 (SD = 3.8 x 10(4) CFU/m3 as measured by filtration and 8.6 x 10(4) CFU/m3 (SD = 5.1 x 10(4) CFU/m3) by impaction. The overall mean respirable concentrations were 9.0 x 10(3) CFU/m3 (SD = 4.1 x 10(3) CFU/m3) measured by filtration and 2.8 x 10(4) CFU/m3 (SD = 2.2 x 10(4) CFU/m3) by impaction. Total and respirable CFU concentrations measured by impaction were significantly (p < 0.05) higher than that by filtration. The persistent strains of microorganisms were various species of the following genera: Staphylococcus, Pseudomonas, Bacillus, Listeria, Enterococcus, Nocardia, Lactobacillus, and Penicillium. It appears that filtration sampling can be used for a qualitative survey of bioaerosols in swine barns while the Andersen sampler is suitable for both quantitative and qualitative assessments.
The objective of this study was to obtain diurnal variation profiles of odor and gas (ammonia [NH3], hydrogen sulfide [H2S], carbon dioxide [CO2]) concentrations and emission rate (OGCER) from confined swine grower/ finisher rooms under three typical weather conditions (warm, mild, and cold weather) in a year. Two grower/ finisher rooms, one with a fully slatted floor and the other with partially slatted floors, were measured for 2 consecutive days under each weather condition. The results revealed that the diurnal OGCER in the room with a fully slatted floor was 9.2-39.4% higher than that with a partially slatted floor; however, no significant differences in the diurnal OGCER were found between these two rooms, except for the NH3 concentrations in August, the NH3 and H2S concentrations and emissions in October, and odor concentrations and emissions in February (p > 0.05). The OGCER variations presented different diurnal patterns as affected by time of day, season, type of floor, ventilation rate, animal growth cycles, in-house manure storage, and weather conditions. Significant diurnal fluctuations in the OGCER (except for the odor concentrations and H2S emissions) were observed in August (p < 0.05); all of the gas emissions in October and the CO2 concentrations and emissions in February also showed significant diurnal variations (p < 0.05). These significant diurnal variations indicated that the OGCER during different periods of a day should be monitored when quantifying OGCER concentrations and emissions; for example, source emission data used in air dispersion modeling to decrease the great incertitude of setback determination using randomly measured data.
eIn this study, we tested the antimicrobial activity of three metal nanoparticles (NPs), ZnO, MgO, and CaO NPs, against Salmonella enterica serovar Enteritidis in liquid medium and on solid surfaces. Out of the three tested metal NPs, ZnO NPs exhibited the most significant antimicrobial effect both in liquid medium and when embedded on solid surfaces. Therefore, we focused on revealing the mechanisms of surface-associated ZnO biocidal activity. Using the global proteome approach, we report that a great majority (79%) of the altered proteins in biofilms formed by Salmonella enterica serovar Enteritidis were downregulated, whereas a much smaller fraction (21%) of proteins were upregulated. Intriguingly, all downregulated proteins were enzymes involved in a wide range of the central metabolic pathways, including translation; amino acid biosynthetic pathways; nucleobase, nucleoside, and nucleotide biosynthetic processes; ATP synthesis-coupled proton transport; the pentose phosphate shunt; and carboxylic acid metabolic processes, indicating that ZnO NPs exert a panmetabolic toxic effect on this prokaryotic organism. In addition to their panmetabolic toxicity, ZnO NPs induced profound changes in cell envelope morphology, imposing additional necrotic effects and triggering the envelope stress response of Salmonella serovar Enteritidis. The envelope stress response effect activated periplasmic chaperones and proteases, transenvelope complexes, and regulators, thereby facilitating protection of this prokaryotic organism against ZnO NPs.
Inhalable and total dust sampling devices were compared for evaluating airborne dust in swine confinement buildings. Measurements from three swine facilities (n = 77 paired means) were obtained by area sampling using the IOM (Institute of Occupational Medicine, Edinburgh, U.K.) inhalable dust sampler and a 37-mm closed-face total (TCF) dust sampler. The overall geometric mean IOM concentration (1.18 mg/m(3), geometric standard deviation [GSD] = 2.00) was significantly greater (P < 0.05) than the overall geometric mean TCF concentration (1.08 mg/m(3), GSD = 1.98). Regression analysis with IOM and TCF values as independent and dependent variables, respectively, yielded a factor of 0.86 (+/-0.04 95% confidence interval), which can be used to estimate TCF values from the IOM measurements. Additional paired sampling data were obtained to compare the following pairs of dust samplers: (1) IOM sampler and conical inhalable sampler (CIS) (n = 20 paired means), (2) IOM and open-face total (TOF) dust samplers (n = 14), (3) CIS and TCF samplers (n = 19), and (4) TCF and TOF samplers (n = 8). Paired t-tests showed significantly (P < 0.05) higher IOM concentrations than the CIS sampler; no significant difference (P > 0.05) was found for the other three pairs compared. It may be necessary to establish work-specific conversion coefficients to obtain a reasonable estimate of worker exposure to total dust from measurements using other types of dust sampling devices.
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