Habitat and Morphology of Listeria monocytogenes

Habitat of Listeria monocytogenes

1. They are the natural pathogens of wide range of animals, birds, fish, ticks and crustacean.
2. They are saprophytic in soil, water, sewage and plants decaying.
3. They occasionally colonizes the human gastrointestinal tract (1-10%).
4. They can be isolated from foods for human consumption, including raw and processed meat, dairy products, vegetables and sea fruit products.
5. Listeria monocytogenes can cause mastitis in cows, from which large number of bacteria can be shed in the milk.
6. They are resistance to the effects of freezing, drying, high heat, high salt and high pH.
7. They can also form biofilms.

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Morphology of Listeria monocytogenes

1. They are gram +ve short rod shaped bacteria.
2. They appear cocco-bacillary in clinical materials.
3. They are small and slender.
4. They are 1-3 µm long and 0.5 µm broad.
5. Poles of the cells are blunt.
6. They are non-sporing.
7. They are non-capsulated.
8. At, 35-37°C, they are non-motile.
9. At 25°C, they are motile and exhibit a tumbling motility.
10. They possess polar flagella (peritrichous) at 25°C.
11. Thirteen serotypes are found.

Genome of Listeria monocytogenes

1. Singular circular chromosome.
2. EGD-e strain is 2,994, 528 base pair long.
3. They have 2853 open reading frame.
4. 331 genes encodes transport protein.
5. GC Content: 39%