Transcript Determining Microbial Assemblages in Snow Using Different Growth

Determining Microbial Assemblages in Snow Using Different
Growth Media
Ama Agyekum
Department of Biological Sciences, York College of Pennsylvania
Plates showing microbial diversity
Introduction
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Studies have been done on the microbial diversity of
thermophiles from extremely hot environments but only a
handful have focused on the microbial diversity of
microbes that live in extremely cold environments
(Jungblut et al 2012).
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Molecular methods of soil and water microbial
populations have been done using genetic sequencing of
small subunits (SSU) ribosomal RNA(Crump et al 2012 ,
Imazaki and Kobori 2010)
Microbial population analyses of snow taken from two
different lakes in Canada revealed a diverse collection of
taxa with a total of 25 bacterial operational taxonomic
units (OTUs) and 23 eukaryotic OTUs (Harding et al 2012).
Bacterial and eukaryotic communities, taken from snow
and ice sheet covers of high mountain top lakes, were
morphologically diverse (Felip et al 1995).
In determining the viability of bacteria, the spread-plate
procedure has been used to isolate and recover bacteria
from environmental samples because it is an easy and
reliable technique (Imazaki and Kobori 2010).
Molecular methods for measuring diversity do not
measure viability. Also, since few microbes can be
cultured, determining the diversity of viable environmental
microbes is challenging.
Viability and diversity can be determined by counting
microbes grown on various enriched and selective medias.
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Objectives
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To investigate the diversity and likely source
environments of microbes in the snow in York College of
Pennsylvania Campus.
To access the ability of different media to culture
microorganisms
Mold and yeast on R2A plates
Material and Methods
R2A
Bacto Yeast Extract .5
Bacto Proteose Peptone No. 3
Bacto dextrose
Bacto Cosamino Acids
Soluble starch
Sodium Pyruvate
Potassium Phosphate dibasic
Magnesium sulfate
Total Grams
0.5g
0.5g
0.5g
0.5g
0.5g
0.3g
0.3g
0.05g
3.15 g
Nutrient agar
Beef extract
Pancreatic Digest of Gelatin
3.0 g
5.0 g
• R2A results
Total grams
8.0 grams
Table. 1. The grams of nutrients in 1 liter of the 2 different media. R2A agar has a wide variety of nutrient but the
total amount per Liter is half as much as the Nutrient agar.
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• Nutrient agar results
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Results
Mold was present in all 5 sites
Bacteria present at sites 1, 2, 4,5
Yeast present in site 1 and 5
Bacteria and yeast was present in sites 1, 2 and 5
Mold was only present in site 4
Conclusion
• There was more microbial diversity on R2A, which was expected
because of nutrient content of agar.
• Site 5 had the highest microbial counts on both plates so location
(closest to city) might influence concentration.
• Yeast counts were low which was probably due to competition for
nutrients (plates overgrown by fungus and/or bacteria).
Literature Cited
Felip, M., Sattler B., Psenner, R., and Catalan, J. 1995.Highly Active Microbial Communities in the Ice and
Snow Cover of High Mountain Lakes. Applied and Environmental Microbiology 61: 2394–2401
Harding, T., Jungblut, A. D., Lovejoy, C. and Warwick , V. F. 2011. Microbes in High Arctic Snow and
Implications for the Cold Biosphere. Available from: http://aem.asm.org/content/77/10/3234.full.
Accessed 2013 September 12
Imazaki, I., and Kobori, Y. (2010). Improving the culturability of freshwater bacteria using FW70, a lownutrient solid medium amended with sodium pyruvate. Canadian Journal Of Microbiology 56: 333-341.
Figure 1. Pictures of bacteria (top right and left), mold (bottom left) and
yeast (bottom right). Pictures were taken with Samsung Illusion camera
phone
Jungblut, A. D., Lovejoy, C. and Vincent, W. F. 2010. Global distribution of cyanobacterial ecotypes in the cold
biosphere. The ISME Journal 4:191–202.
Morris, C. E et al. 2008. The life history of the plant pathogen Pseudomonas syringae is linked to the water
cycle. Available from:http://www.nature.com/ismej/journal/v2/n3/full/ismej2007113a.html. Accessed
2013 September 13.