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Are we biologically safe with snow precipitation? A case study in beijing.

Shen F, Yao M - PLoS ONE (2013)

Bottom Line: The results revealed that snow samples had bacterial concentrations as much as 16000 CFU/ml for those cultured at 26°C, and the conductance levels ranged from 5.6×10(-6) to 2.4×10(-5) S.Absent from the outdoor air, certain human, plant, and insect fungal pathogens were found in the snow samples.The results here suggest that snow precipitations are important sources of fungal pathogens and ice nucleators, thus could affect local climate, human health and agriculture security.

View Article: PubMed Central - PubMed

Affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China.

ABSTRACT
In this study, the bacterial and fungal abundances, diversities, conductance levels as well as total organic carbon (TOC) were investigated in the snow samples collected from five different snow occurrences in Beijing between January and March, 2010. The collected snow samples were melted and cultured at three different temperatures (4, 26 and 37°C). The culturable bacterial concentrations were manually counted and the resulting colony forming units (CFUs) at 26°C were further studied using V3 region of 16 S rRNA gene-targeted polymerase chain reaction -denaturing gradient gel electrophoresis (PCR-DGGE). The clone library was constructed after the liquid culturing of snow samples at 26°C. And microscopic method was employed to investigate the fungal diversity in the samples. In addition, outdoor air samples were also collected using mixed cellulose ester (MCE) filters and compared with snow samples with respect to described characteristics. The results revealed that snow samples had bacterial concentrations as much as 16000 CFU/ml for those cultured at 26°C, and the conductance levels ranged from 5.6×10(-6) to 2.4×10(-5) S. PCR-DGGE, sequencing and microscopic analysis revealed remarkable bacterial and fungal diversity differences between the snow samples and the outdoor air samples. In addition, DGGE banding profiles for the snow samples collected were also shown distinctly different from one another. Absent from the outdoor air, certain human, plant, and insect fungal pathogens were found in the snow samples. By calculation, culturable bacteria accounted for an average of 3.38% (±1.96%) of TOC for the snow samples, and 0.01% for that of outdoor air samples. The results here suggest that snow precipitations are important sources of fungal pathogens and ice nucleators, thus could affect local climate, human health and agriculture security.

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Culturable bacterial concentrations when cultured at three different temperatures (4, 26, and 37°C) in different snow samples and also in an outdoor air sample collected in Beijing from January to March, 2010.Collected snow samples were melted at room temperature immediately before the analysis; snow data represent averages of five snow samples collected for each snow occurrence on a particular date, and error bars represent standard deviation of three replicates; blank agar plates were used as negative controls.
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pone-0065249-g001: Culturable bacterial concentrations when cultured at three different temperatures (4, 26, and 37°C) in different snow samples and also in an outdoor air sample collected in Beijing from January to March, 2010.Collected snow samples were melted at room temperature immediately before the analysis; snow data represent averages of five snow samples collected for each snow occurrence on a particular date, and error bars represent standard deviation of three replicates; blank agar plates were used as negative controls.

Mentions: This study investigated the biological contents, conductance levels as well as total organic carbons in snow samples collected from five snow occurrences that happened during January-March 2010 in Beijing, and the relevant results were compared among them as well as with those in outdoor air samples. Fig. 1 shows the culturable bacterial concentrations in the snow samples and outdoor air samples obtained by culturing at three different temperatures: 4, 26 and 37°C. As observed in Fig. 1, in most cases the culturing of snow samples at 26°C resulted in the highest culturable bacterial concentrations, followed by culturing at 4 and 37°C. For two snow samples, the culturing at 4°C produced slightly higher concentrations than the culturing at 26°C. For all samples, the culturing at 37°C resulted in lowest concentration levels. Compared to the snow samples, outdoor air samples cultured at 4°C for 2 days produced very few colony forming units (below 10) under similar conditions. The culturable bacterial concentration levels for the snow samples here were found to range approximately from 2750 to 16000 CFU/ml of melted snow at 26°C, while those for the outdoor air sample were about 1600 CFU/m3. These data suggested that bacteria were abundant in the snow samples collected, and bacteria in the snow samples can be more active at lower temperatures than those (likely in the state of viable but not culturable) in outdoor air samples, implying they might play possible roles in ice nucleation and cloud formation. ANOVA tests indicated there were statistically significant differences in the bacterial concentrations obtained for five snow samples for different occurrences at different incubation temperatures (p-values = 0.001–0.028).


Are we biologically safe with snow precipitation? A case study in beijing.

Shen F, Yao M - PLoS ONE (2013)

Culturable bacterial concentrations when cultured at three different temperatures (4, 26, and 37°C) in different snow samples and also in an outdoor air sample collected in Beijing from January to March, 2010.Collected snow samples were melted at room temperature immediately before the analysis; snow data represent averages of five snow samples collected for each snow occurrence on a particular date, and error bars represent standard deviation of three replicates; blank agar plates were used as negative controls.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3675146&req=5

pone-0065249-g001: Culturable bacterial concentrations when cultured at three different temperatures (4, 26, and 37°C) in different snow samples and also in an outdoor air sample collected in Beijing from January to March, 2010.Collected snow samples were melted at room temperature immediately before the analysis; snow data represent averages of five snow samples collected for each snow occurrence on a particular date, and error bars represent standard deviation of three replicates; blank agar plates were used as negative controls.
Mentions: This study investigated the biological contents, conductance levels as well as total organic carbons in snow samples collected from five snow occurrences that happened during January-March 2010 in Beijing, and the relevant results were compared among them as well as with those in outdoor air samples. Fig. 1 shows the culturable bacterial concentrations in the snow samples and outdoor air samples obtained by culturing at three different temperatures: 4, 26 and 37°C. As observed in Fig. 1, in most cases the culturing of snow samples at 26°C resulted in the highest culturable bacterial concentrations, followed by culturing at 4 and 37°C. For two snow samples, the culturing at 4°C produced slightly higher concentrations than the culturing at 26°C. For all samples, the culturing at 37°C resulted in lowest concentration levels. Compared to the snow samples, outdoor air samples cultured at 4°C for 2 days produced very few colony forming units (below 10) under similar conditions. The culturable bacterial concentration levels for the snow samples here were found to range approximately from 2750 to 16000 CFU/ml of melted snow at 26°C, while those for the outdoor air sample were about 1600 CFU/m3. These data suggested that bacteria were abundant in the snow samples collected, and bacteria in the snow samples can be more active at lower temperatures than those (likely in the state of viable but not culturable) in outdoor air samples, implying they might play possible roles in ice nucleation and cloud formation. ANOVA tests indicated there were statistically significant differences in the bacterial concentrations obtained for five snow samples for different occurrences at different incubation temperatures (p-values = 0.001–0.028).

Bottom Line: The results revealed that snow samples had bacterial concentrations as much as 16000 CFU/ml for those cultured at 26°C, and the conductance levels ranged from 5.6×10(-6) to 2.4×10(-5) S.Absent from the outdoor air, certain human, plant, and insect fungal pathogens were found in the snow samples.The results here suggest that snow precipitations are important sources of fungal pathogens and ice nucleators, thus could affect local climate, human health and agriculture security.

View Article: PubMed Central - PubMed

Affiliation: State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, China.

ABSTRACT
In this study, the bacterial and fungal abundances, diversities, conductance levels as well as total organic carbon (TOC) were investigated in the snow samples collected from five different snow occurrences in Beijing between January and March, 2010. The collected snow samples were melted and cultured at three different temperatures (4, 26 and 37°C). The culturable bacterial concentrations were manually counted and the resulting colony forming units (CFUs) at 26°C were further studied using V3 region of 16 S rRNA gene-targeted polymerase chain reaction -denaturing gradient gel electrophoresis (PCR-DGGE). The clone library was constructed after the liquid culturing of snow samples at 26°C. And microscopic method was employed to investigate the fungal diversity in the samples. In addition, outdoor air samples were also collected using mixed cellulose ester (MCE) filters and compared with snow samples with respect to described characteristics. The results revealed that snow samples had bacterial concentrations as much as 16000 CFU/ml for those cultured at 26°C, and the conductance levels ranged from 5.6×10(-6) to 2.4×10(-5) S. PCR-DGGE, sequencing and microscopic analysis revealed remarkable bacterial and fungal diversity differences between the snow samples and the outdoor air samples. In addition, DGGE banding profiles for the snow samples collected were also shown distinctly different from one another. Absent from the outdoor air, certain human, plant, and insect fungal pathogens were found in the snow samples. By calculation, culturable bacteria accounted for an average of 3.38% (±1.96%) of TOC for the snow samples, and 0.01% for that of outdoor air samples. The results here suggest that snow precipitations are important sources of fungal pathogens and ice nucleators, thus could affect local climate, human health and agriculture security.

Show MeSH