Role of silicon in modulating the internal morphology and growth of Mycobacterium tuberculosis

Abstract

Silicon is known to enhance the growth and pathogenicity of Mycobactenum tuberculosis. In this study the pattern of growth of different strains of M.tuberculosis was studied on a carbon free silicon based culture medium and compared with that on conventional media. Thirty-two strains of M.tuberculosis from mostly clinical isolates were serially propagated on a carbon free silicate medium and on different conventional media using standard inocula There was initial good growth on the silicon based medium in comparison with the conventional media. However, the growth was considerably reduced after early serial transfers but improved again in late serial cultures. The initial good growth appears to be due to increased activity of silicon induced fatty acid synthase and the late improvement due to slow adaptation of M.tuberculosis to the carbon free metaboiism by the formation of silicic acid esterified cell wall and silicon induced genetic alteration. All these changes were probably responsible for the formation of fibrous, ropelike structures and dense granules seen under electron microscope. Since the silicon content of the lung tissue is comparatively higher than many other tissues of the human body, it could play a role in the pathogenicity of tuberculosis in the lungs.