Question

These questions are for ENTEROCOCCUS FAECALIS:

what is the Gram Stain, Cell shape, Arrangement, Colony characteristics (pigment, shape, texture, elevation , margin of growth on an agar plate), Dextrose (Glucose) Fermentation, Lactose Fermentation, Mannitol Fermentation, Methyl Red, Voges-Proskauer, Citrate Utilization, Starch Hydrolysis, Litmus Milk, Catalase, oxidase, hydrogen sulfide production, phenylethyl alcohol agar and Mannitol salts agar, and MacConkey agar of Enterococcus Faecalis? THANK YOU!

Answer 1

Enterococcus Faecalis

1. Gram stain- It is a staining technique which is used for bacterial species to distinguish between Gram positive and Gram negative. Enterococcus Faecalis is Gram- Positive.

2. Cell shape- It having Cocci shape which present in short chains. The cocci are spherical and oval with size 0.6 to 2.0 micrometers.

3. Arrangement- It may arranged in clusters, Short chains, Diplococci and, single cocci.

4. Colony characteristics-

a) On blood agar- It having non- haemolytic (gamma) colonies under 24 hours of incubation in aerobic condition at 37degree celcius temperature.

b) On bile Esculin azide agar- The black zones are present around the small oval colonies. and it is so because Esculetin combines with ferric ions and produce black complex.

c) On MacConkey agar - On MacConkey agar they form transparent, opalescent and pink coloured colonies.

d) On Mannitol salts agar- These bacteria are salt tolerant and produce yellow coloured colony on MSA. They can easily ferment the mannitol and produce lactic acid.

Fermentation- It is the process of enzymatic breakdown of any organic substance by bacteria, yeast etc under anaerobic conditions.

1) Dextrose fermentation- positive It ferment glucose without gas production.

2) Lactose Fermentation- positive It ferments lactose under acid production on purple agar.

3) Mannitol Fermentation- positive It ferment mannitol on MSA and produce acid.

BioChemical tests-

1) Methyl Red- It donot show methyl red test.

2) Voges-Proskauer- Positive

3) Citrate Utilization - Negative

4) Starch Hydrolysis-  Positive

5) Litmus Milk - Positive It produces reduction of litmus milk. This test is used to distinguish between different species of bacteria.

6) Catalase, oxidase - Negative The oxidase test detects the presence of cytochrome oxidase system. it is negative becoz donot produce intracellular oxidase enzyme.

7) hydrogen sulfide production - Negative

8) phenylethyl alcohol agar- It is selective media for Gram- positive bacteria, main purpose of it is to reduce the growthof Gram- negative bacteria.

9) Mannitol salts agar- These bacteria are salt tolerant and produce yellow coloured colony on MSA. They can easily ferment the mannitol and produce lactic acid.

10) MacConkey agar - On MacConkey agar they form transparent, opalescent and pink coloured colonies.