Why are Mycobacterium digested with sodium hydroxede for 30min prior to staining?

Answer 1

First of all I suggest you to check and correct the mistakes which you have done in your question. It is sodium hydroxide (NaOH) rather than sodium hydroxede, the mycobacterium is not digested rather sodium hydroxide (NaOH) is used to homogenize and decontaminate the sputum sample which is generally collected in case of pulmonary tuberculosis. The sputum may contain the mycobacterium along with other normal commensal flora of the upper respiratory tract and the oral cavity. The load of mycobacterium may be less and it may be entrapped in the mucous part of the sputum sample, therefore, the process of homogenization is done using sodium hydroxide to digest the mucous, liberate the entrapped mycobacterium and destroy the contaminating commensal flora.

Homogenization and decontamination is generally done by different methods but Petroff's method is the most commonly used. The sample is then neutralized by adding HCl (hydrocholoric acid) and is used for smear and culture.