A review on the shape changes in pathogenic bacteria with emphasis on Mycobacterium tuberculosis

Bacteria show a plenty of cellular shapes and can alter their forms. The bacterial cell shape is functionally important. Bacteria have a number of options to select their shapes in order to uptake more nutrient, motility, attachment to surface, symmetrical division of chromosomal elements, and localization of complex secretion apparatuses. Some factors including peptidoglycan and cytoskeleton-like proteins can regulate and keep the bacterial shape. In the case of Mycobacterium tuberculosis, the reported morphological variation in the pathogen are classified into two categories; those which frequently seen at exponential phase of growth that is rod, V, Y-shape, branched, or buds, and those that are seen occasionally under stress or environmental conditions which are round, oval, ultra-virus, spore-like, and cell wall defiant or L-forms. Growth conditions and age of the cells can influence on the shape and size of the pathogen in a range from coccobacilli to long rods. Under unsuitable conditions including starvation or oxygen deprivation, tubercle bacillus assumed a swollen shape without making the vacuolar or globoid bodies. The physical circumstances and nutritional feature will control the temporary lifestyle of the pathogen.