Chloroplasts as cellular factories for the cost-effective production of cellulases.

Chloroplasts are vital photosynthetic organelles in plant cells that carry out several important cellular functions including synthesis of amino acids, fatty acids, and lipids and metabolism of nitrogen, starch, and Sulphur to sustain the homeostasis in plants. These organelles have got their own genome, and related genetic machinery to synthesize required proteins for various plant functions. Genetic manipulations of the chloroplast genome for different biotech applications has been of great interest due to desired features including the availability of operonal mode of gene expression, high copy number, and maternal mode of inheritance (in the most field crops). Their capacity to often express transgenes at high levels make it a cost-effective platform for the production of foreign proteins, particularly high-value targets of industrial importance, at large scale. This article reviews briefly the research work carried out to produce cellulolytic enzymes in higher plant chloroplasts. The challenges and future opportunities for the same are also discussed.