Jeff Bowman         

Senior Thesis

 

 

 

 

Halomonas sp.

My Project

In some regions of the world inter-annual variations in precipitation constitute a major feature of the climate.  In these regions salinity changes within closed basins can be used to track precipitation changes.  In wet years rain dilutes the water of lakes and ponds, decreasing salinity.  In dry years evaporation concentrates the salts of lakes and ponds, increasing salinity.

 

These changes in salinity are recorded by the physiological responses of the microorganisms which inhabit these bodies of water.  When these microorganisms die some become embedded within lake sediment.  A sediment core pulled from the lake will retain some traces of these physiological responses.  If correctly correlated to salinity by laboratory experiments and field observations these physiological “proxies” can identify salinity trends and therefore precipitation trends.

 

I hope to identify a potential salinity proxy within the lipids of halotolerant bacteria of the genii Halomonas and Salinivibrio isolated from hypersaline lakes in Saskatchewan, Canada.  A lipid biomarker (lipid unique to the target organism) that changes relative to salinity will be identified and paired with a lipid biomarker that does not change relative to salinity.  The ratio of these two biomarkers could be correlated with salinity and developed into a proxy.

 

At this time I have successfully isolated Halomonas and Salinivibrio, and have cultured Salinivibrio at salinities as high as 170 g L^-1.  Lipid fractionation and analysis are being conducted by a combination of column and gas chromatography coupled with a flame ionization detector (GC-FID) and mass spectrometer (GC-MS).

 

Click on the link below for a copy of our article in Saline Systems describing the saline lake environments where the study organisms originated.

 

Bowman JS and Sachs JP.   2008.  Chemical and physical properties of some saline lakes in Alberta and Saskatchewan.  Saline Systems, 4:3. 

 

Click on the link below to view the final version of my senior thesis.  Although my project will continue through the summer, the manuscript details my techniques and initial results.  To aid in viewing, jpg images of the tables and figures are provided through the below links.

 

Manuscript

Table 1

Table 2

Table 3

Table 4

Figure 1

Figure 2

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Figure 4

Figure 5

 

I have developed a reduced lipid media for and unclassified strains of Halomonas.  Initial results from the quantification of the lipids produced by this organism suggest some very strong correlations with salinity.  At this time I am working to identify the compounds involved in these correlations using mass spectrometry.

Dense microbial growth in a puddle supersaturated with sodium sulfate.    Photo from Chaplin, SK.