Listeria sp. Identification Test

Listeria sp.

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Morphology: Rods

Gram: Positive

Catalase: Positive

Respiratory system: Facultative anaerobe 

Motility: Peritrichous

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Tests to identify the genus

• Hemolysis test - Sheep blood agar
• CAMP factor - Sheep blood agar
• Mixed acid or butane-diol fermentation - Clark and Lubs medium
• Sugar fermentation: xylose, mannitol, rhamnose
• Nitrate reductase

Culture

PALCAM agar

Listeria sp. on PALCAM agar

On BD PALCAM Listeria Agar, colonies of Listeria appear gray-green with a black halo. Confirmation of the presence of Listeria is made following subculture onto appropriate media and biochemical/serological identification. Colonies of mannitol-fermenting organisms such as staphylococci, which may grow on this medium, appear yellow with a yellow halo.

Refererence: BD™ [Link]

ALOA™ agar

Listeria monocytogenes on ALOA™

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Bacillus sp. Identification Test

Bacillus sp.

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Morphologie: Rods

Gram: Positive

Catalase: Positive

Respiratory system: Facultative aerobe (B. subtilis: Obligate aerobe)

Motility: Peritrichous
Characteristic: Produces endospores

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Tests to identify spieces

• CO₂ production - Gibson Abdel Malek (GAM) medium
• Acetyl-methyl-carbinol (AMC) production - AMC medium
• Indole production - Peptone water indole-free
• Urease test - Christensen medium
• Citrate utilization - Simmons medium
• Growth at 65° C
• 7 % NaCl resistance
• Proteolysis test
• Gelatinase test
• Amylase test
• Hemolysis - Sheep blood agar
• Sugar fermentations: glucose, arabinose, mannitol and xylose

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Clostridium sp. Identification Test

Clostridium sp.

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Morphology: Rods

Gram: Positive

Catalase: Negative
Oxidase: Negative

Respiratory system: Obligate anaerobe

Motility: Motile

Characteristic: Produces endospores

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Tests to identify the genus

• API 20A
• Rosenow medium
• Nitrate reductase test
• Proteolysis and acidification
• Sulfites reduction
• Lecithinase test

Test to identify butyric Clostridium

• Lactate utilization: butyric acid and CO₂ production - Bryant and Burkey medium

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Lactic Acid Bacteria (rods) Identification Test

Lactic acid bacteria (rods)

Lactobacillus casei, L. plantarum, L. fermentum, L. acidophilus, L. bulgaricus and L. helveticus

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Morphology: Rods

Gram: Positive

Catalase: Negative
Motility: Non-motile
Respiratory system: Facultative aerobe

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Tests to identify the genus Lactobacillus 

• CO₂ production from glucose
• Culture at 15° C and 45° C - MRS medium
• Arginine dihydrolase - Moeller medium
• Sugar fermentation : ribose, lacotse, maltose, sorbitol or sucrose

Test to identify the species

• Esculin hydrolysis - Esculin agar
• Acidification and reduction

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Lactic Acid Bacteria (cocci) Identification Test

Lactic acid bacteria

Lactococcus lactis, Lactococcus lactis subsp. lactis biovar diacetylactis, Lactococcus lactis subsp. cremoris, Streptococcus thermophilus, Pedicoccus acidilactici and Leuconostoc sp.

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Morphology: Cocci

Gram: Positive

Catalase: Negative
Respiratory system: Facultative anaerobe

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Tests to identify the genus

• Growth at 10° C and 45° C - Elliker/M17 broth
• NaCl resistance: 2, 4, 6 % NaCl
• CO2 production - MRS medium with bell

Tests to identify the species

• Acidification and reduction test
• Citratase test
• Arginine dihydrolase test - Moeller medium
• Sugar fermentations: glucose, sucrose, ribose, xylose, maltose, lactose

Please, feel free to comment if there is any mistake.