Microbiological Media Images

Please click on the links below to view various images of Microbiological Media. In most cases the media will be presented before inoculation and with a positive and negative result.

IMViC Test - Tryptone Broth before adding Kovacs

 

 

Tryptone Broth after addition of Kovacs

(+) Indole test on left   ---   (-) Indole test on right

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Carbohydrate Fermentation tubes

Left is (+)  --  Middle indicates (+) with gas  -- Right is a (-) test

 

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Gelatin Hydrolysis test

Test tube on left is (+) as indicated by liquid nature

 

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IMViC test – Simmons Citrate

Test tube on right is (+) as indicated by blue color

 

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Litmus milk

1 control, 2 pink = acid, 3 white = reduction, 4 & 5 stormy fermentation, 6 blue = alkaline

 

Litmus Milk same as above different lighting

 

Litmus milk

Close up of Stormy Fermentation

Notice the Whey – clear fluid on top of curd

 

 Litmus milk

Stormy Fermentation notice the tracks of the gas bubbles through the curd

 

Litmus milk – compare the reduction to the control

 

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MR-VP without reagents

 

 

MR-VP tubes after addition of Methyl Red  --  Red is (+) test

 

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Nitrate Tubes after 24 hours – Tube on left has no gas in Durham tube

Test tube on right has gas – this is a (+) test – the Nitrate was converted to Nitrite then to N2 gas

 

 

Nitrate tube after 24 hour inoculation and addition of nitrite pillow – Red is (+) for

nitrite indicating the bacteria can reduce nitrate

 

Nitrate tubes after 24 hour inoculation and addition of nitrite pillows.  Tube 1 is (-) it did not turn red

and has no gas, tube 2 is (+) because it is red indicating presence of nitrite, tube 3 is also (+) while there is

no red color to indicate the presence of nitrite there is gas

 

 

 

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Peptone Iron Agar (PIA) 

Tubes 2 & 3 show the black precipitate that is the (+) indicator for production of H2S

 

 Peptone Iron Agar (PIA) 

 

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Skim Milk plate

Notice the faint clearing around the Bacillus bacteria, this

indicates that Bacillus produces exoenzymes that can digest casein

 

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Starch agar plate

Containing two bacteria – this test will determine if the bacteria possess the ability to digest starch.

 

This is the same Starch Agar plate after the addition of iodine. 

The iodine reacts with starch to for a blue/black compound. 

Around the Bacillus bacteria there is a clear zone, indicating that the Bacillus can digest starch.

 

 

 

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Tributyrin Agar

Tests for ability to digest lipids. 

Psuedomonas has a clear zone around it  indicating that it can digest lipids.

 

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Urea Test

Tube 1 is salmon color = uninnoculated

Tube 2 is Cerise (cherry red) positive test for urea hydrolysis

Tube 3 is yellow negative test for urea hydrolysis

 

 

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IMViC test Vogues Proskauer

Innoculated but prior to addition of Barritt’s A and B

 

Vogues Proskauer test after addition of  Barritt’s A& B and waiting 20-25 minutes.

The red color on the right tube is a (+) test.

 

 

 

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Mannitol salt 

This plate contains the sugar (mannitol), NaCL (salt), and phenol red (pH indicator).

If the bacteria can tolerate the salt you will observe colony growth. If it can not tolerate the salt the plate will have no

growth or pinpoint colonies. If the bacteria can tolerate the salt and eat the mannitol an acid is produced causing the pH indicator to give a yellow appearance to the plate.

 

 

Staph a growing on Mannitol salt – able to digest the mannitol and tolerate the salt

 

 

Staph e growing on Mannitol salt – cannot digest the mannitol but can tolerate the salt

 

 

 Micrococcus luteus unable to grow on Mannitol salt

 

 

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 E. coli on an EMB plate

 

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Blood Agar plate

 

 

Staph E on a Blood Agar plate – notice the slight hemolysis (alpha hemolysis)

 

 

 

 

Staph A on Blood Agar plate – notice clear zones of complete hemolysis (Beta Hemolysis)

 

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SS agar clear versus dark colonies

 

 

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MacConkey agar

Lactose fermenting bacteria show purple colored colonies