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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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Neighbour-joining phylogenetic tree showing the relationship of representative sequences of OTUs in all snow samples and reference sequences in GenBank.It was constructed based on analysis of 16 S rRNA gene sequences of bacteria clone libraries from snow samples. Clone names from 1 (2010) to 4 (2010) represent samples collected on January 1, March 1, 8, 14, Feb 7 of 2010. Clone name 5 (2011) represents snow samples collected on Feb 27 of 2011. The capital “C” in the clone name means Clone. An Escherichia coli strain ATCC 25922 (dq 360844.1) was used as the outgroup.
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pone-0065249-g005: Neighbour-joining phylogenetic tree showing the relationship of representative sequences of OTUs in all snow samples and reference sequences in GenBank.It was constructed based on analysis of 16 S rRNA gene sequences of bacteria clone libraries from snow samples. Clone names from 1 (2010) to 4 (2010) represent samples collected on January 1, March 1, 8, 14, Feb 7 of 2010. Clone name 5 (2011) represents snow samples collected on Feb 27 of 2011. The capital “C” in the clone name means Clone. An Escherichia coli strain ATCC 25922 (dq 360844.1) was used as the outgroup.

Mentions: Here, a V3 region of 16 S rRNA gene clone library was constructed from four snow samples collected in 2010 and one snow sample collected in 2011 to characterize the diversity of the snow bacterial communities and to identify the dominant taxonomic groups. As shown in Fig. 5, all snow samples were dominated by the representatives of genus Bacillus. On one hand, this finding might due to the liquid culturing method used to retrieve the bacteria of snow samples. Spore-forming organisms, such as Bacillus species and other Gram-positives, tend to dominate culture-dependent surveys of airborne microbial diversity [18]. On the other hand, Bacillus species show high resistance to environmental stresses, including UV light exposure, desiccation, and the presence of oxidizers [50]. In previous studies, Bacillus species had been collected from spacecraft and facility surfaces, and Bacillus pumilus was found to be the second most dominant species among the aerobic spore-forming bacteria [51], which was also found in snow samples. Bacterial strain closely related to Bacillus flexus was also isolated from surface snow samples collected from Antarctica [52]. Our results here imply that Bacillus species could serve as an efficient ice nucleator.


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

Shen F, Yao M - PLoS ONE (2013)

Neighbour-joining phylogenetic tree showing the relationship of representative sequences of OTUs in all snow samples and reference sequences in GenBank.It was constructed based on analysis of 16 S rRNA gene sequences of bacteria clone libraries from snow samples. Clone names from 1 (2010) to 4 (2010) represent samples collected on January 1, March 1, 8, 14, Feb 7 of 2010. Clone name 5 (2011) represents snow samples collected on Feb 27 of 2011. The capital “C” in the clone name means Clone. An Escherichia coli strain ATCC 25922 (dq 360844.1) was used as the outgroup.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0065249-g005: Neighbour-joining phylogenetic tree showing the relationship of representative sequences of OTUs in all snow samples and reference sequences in GenBank.It was constructed based on analysis of 16 S rRNA gene sequences of bacteria clone libraries from snow samples. Clone names from 1 (2010) to 4 (2010) represent samples collected on January 1, March 1, 8, 14, Feb 7 of 2010. Clone name 5 (2011) represents snow samples collected on Feb 27 of 2011. The capital “C” in the clone name means Clone. An Escherichia coli strain ATCC 25922 (dq 360844.1) was used as the outgroup.
Mentions: Here, a V3 region of 16 S rRNA gene clone library was constructed from four snow samples collected in 2010 and one snow sample collected in 2011 to characterize the diversity of the snow bacterial communities and to identify the dominant taxonomic groups. As shown in Fig. 5, all snow samples were dominated by the representatives of genus Bacillus. On one hand, this finding might due to the liquid culturing method used to retrieve the bacteria of snow samples. Spore-forming organisms, such as Bacillus species and other Gram-positives, tend to dominate culture-dependent surveys of airborne microbial diversity [18]. On the other hand, Bacillus species show high resistance to environmental stresses, including UV light exposure, desiccation, and the presence of oxidizers [50]. In previous studies, Bacillus species had been collected from spacecraft and facility surfaces, and Bacillus pumilus was found to be the second most dominant species among the aerobic spore-forming bacteria [51], which was also found in snow samples. Bacterial strain closely related to Bacillus flexus was also isolated from surface snow samples collected from Antarctica [52]. Our results here imply that Bacillus species could serve as an efficient ice nucleator.

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
Related in: MedlinePlus