Question

Mycoplasma like mollicutes, which do not require sterols in culture medium are called as:

• A. PPLO
• B. MLO
• C. Acholeplasma
• D. Spirochaetes

Answer 1

Answer: (C)

Acholeplasma

Mycoplasma, the smallest prokaryotic organisms that have rigid plasma membrane rich in sterols and lipoglycan. Mycoplasma obtains sterols from the growth medium and incorporates in their membranes. Mycoplasmas were discovered as the causative agents of a sheep disease and were first named PPLO, pleuropneumonia-like organisms. Nocard and Roux, 1896, were first to isolate Mycoplasma mycoides, the causative agent of contagious bovine pleuropneumonia and coined the term “mycoplasma” for them. Thus, PPLO is the name first given to Mycoplasma.

MLOs are Mycoplasma-like organisms that lack cell wall but have a rigid plasma membrane and exhibit pleomorphism; they also exhibit sterol requirement as Mycoplasma.

Acholeplasma are the mollicutes that synthesise carotenoids which serve the function of sterols and hence, they do not have an absolute requirement for sterols from the growth medium.

Spirochaetes are Gram-positive bacteria with well-defined cell wall and high G+C% and hence, are not mollicutes.

Thus, the correct answer is option (C).