Isolation and Characterization of Leuconostoc Mesenteroides From Cheese 3

The results and interpretation of growth, characterization, and biochemical activity of L. mesenteroides.

Isolation of Leuconostoc

From the cheddar cheese, two types of colonies were isolated. One colony was yellow colored shiny, smooth and entire marginated. And the other was pale white, slimy, smooth colonies. Gram staining results showed: 1) gram positive bacilli, 2) gram positive cocci, and 3) gram positive coccobacilli. So to isolate Leuconostoc from other LAB organisms, vancomycin was added to the MRS medium.

Characterization of Leuconostoc

S.No Cultural & Biochemical characteristics Results
1 Gram’s staining Gram positive, coccobacilli, with rounded ends.
2 Motility Motile
3 Capsule staining Non-capsulated
4 Spore staining Non-sporing
5 Growth at 37oC +
6 Growth at 30oC +
7 Growth at 4oC +
On MRS medium:
8 At 37oC Pale yellow colored, smooth, slimy, entire marginated, convex colonies.
9 At 4oC In refrigeration, colonies turned white, and slow growth was observed.
10 On MacConkey agar medium Lactose fermenting, pink colored colonies.
11 On blood agar medium Non-hemolytic, colorless colonies.
Biochemical tests:
12 Indole -
13 Methyl red -
14 Voges Proskauer +
15 Citrate -
16 Urease -
17 Arginine -
Carbohydrate fermentation tests:
18 Glucose + (acid and gas)
19 Arabinose +
20 Lactose +
21 Mannitol -
22 Sucrose +
23 Dextrose +
24 Maltose +

Discussion

From the three different colonies isolated from cheese (fig-1), Leuconostoc was isolated separately by its specific vancomycin resistant character (fig-2). Species was identified by its biochemical and carbohydrate tests. First, Leuconostoc mesenteroides was differentiated on the basis of Arginine hydrolysis. Only L.cremoris and L.mesenteroides is Arginine hydrolyser and both are possible in cheese. Secondly, Arabinose fermenters. Between both the species, only L.mesenteroides is Arabinose fermenters (Bettache Guessas and Mebrouk Kihal, 2004). Thus the species was confirmed as Leuconostoc mesenteroides.

Fig-1. Isolation of Leuconostoc species from cheese (different colonies)

Fig-2. Isolation of Leuconostoc in MRS medium added with vancomycin

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2 Responses to “Isolation and Characterization of Leuconostoc Mesenteroides From Cheese 3”
  1. Gerardo Moreno Says...

    On July 6, 2011 at 2:30 pm

    Hello my name is Gerardo Moreno, by now I\’m working on the same isolation, your article has been pretty helpful, I\’m interested in nowing the amount used of vancomycin. thanks alot greetings from Mexico


  2. tefera Says...

    On May 11, 2012 at 5:22 am

    hello i am Tefera Tadesse currently i am working on cassava fermentative microorganism isolation leuconostoc mesentriodes and lactobacillus plantarium.would you pls help in how to carry out biochemical, phsiological and carbohydrate test with proceduers. Thanks to much greeting from Ethiopia.


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