Osmotic pressure

To test an organism ability to grow under osmotic pressure, high solute tolerance, and the ability of an organism to drive transport processes to balance out the cell.  Organisms were grown on Brain Heart Infusion agar with varying concentrations of salt.  
                            0.85% NaCl BHI/Control


0.85% NaCl in BHI (Brain heart infusion agar) is normal osmotic pressure.  Controls are run to make sure all of the organisms used in the experiment are growing normally.  
All plate were inoculated as follows:
Top of plate: Bacillus subtilus
Lower left: Staphylococcus aureus
Lower Right: E. coli



Halotolerant/Osmotolerant

                        5% NaCl in BHI




5% NaCl in BHI. Bacterial species that will grow in the presence of NaCl but do not require it.

Halophile

7.5% NaCl in BHI

10% NaCl in BHI
      

       
      






        

     Bacterial species that can grow with an osmotic pressure of >3 to 20% NaCl.
        S. aureus grows at increased NaCl but does not require NaCl for growth.  S. aureus is part of the normal flora of the skin and is exposed to salt in sweat growing in salt concentrations of up to 15%.


       Extreme Halophiles/Extremeophile:

         Salt loving Bacterial species that will grow in an osmotic pressure range of 15 to 25% NaCl.  Bacterial species requires NaCl to grow. 
            Ex: Halobacterium salinarum (Archaeal species) Gram (-) marine organism.



                                           All images Copyright T.Sturm















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