MYCOPLASMAS {CLASS MOLLICUTES}
The class Mollicutes has five orders and six
families. The best studied genera are found in this orders,
·
Mycoplasmatales (Mycoplasma,
Ureaplasma)
·
Entomoplasmatales (Entomoplasma,
Mesoplasma, Spiroplasma)
·
Acholeplasmatales (Acholeplasma)
·
Anaeroplasmatales (Anaeroplasma,
Asteroleplasma)
1. Members of the class Mollicutes are commonly called as Mycoplasmas.
2. These bacteria lack cell wall and cannot synthesize peptidoglycan precursors.
3. They are penicillin resistant but susceptible to lysis by osmotic shock and detergent treatment.
4. They are usually facultative anaerobes but some are obligate anaerobes.
5. The complete genome of Mycoplasma genitalium, parasite human genital and respiratory tracts has been sequenced.
6. The metabolism of Mycoplasmas are not unusual, although they are deficient in several biosynthetic sequences and often require sterols, fatty acids, vitamins, amino acids, purines and pyrimidines. Those Mycoplasmas needing sterols incorporate them into the plasma membrane.
7.Some produce ATP by the Emden-Meyerhof pathway and lactic acid fermentation. Others catabolize arginine or urea to generate ATP.
8. Mycoplasmas are remarkably widespread and can isolated from any animals, plants, the soil, and even compost piles
9. In animals, Mycoplasmas colonize mucous membranes and joints and often are associated with the diseases of the respiratory and urogenital tracts.
10. Mycoplasmas cause several major diseases in livestock. M. Pneumonia causes primary atypical pneumonia in humans.
|
Genus |
No. of recognized
species |
G+C content (kpb) |
Cholesterol requirements |
Habitat |
|
Acholeplasma |
13 |
26 – 36 |
No |
Animals,
some plants and insects |
|
Anaeroplasma |
4 |
29 – 34 |
Yes |
Bovine or
Ovine rumen |
|
Asteroleplasma |
1 |
40 |
No |
Bovine or
Ovine rumen |
|
Entomoplasma |
5 |
27 – 29 |
Yes |
Insects and
plants |
|
Mesoplasma |
12 |
27 – 30 |
No |
Insects and
plants |
|
Mycoplasma |
104 |
23 – 40 |
Yes |
Humans,
animals |
|
Spiroplasma |
22 |
25 – 30 |
Yes |
Insects and
plants |
|
Ureaplasma |
6 |
27 – 30 |
Yes |
Humans,
animals |
