During the late eighties for the first time in the history of mankind Barta et al. successfully developed human gonadotropin, a therapeutic protein in recombinant tobacco and sunflower plants (Barta et al. 1986) and with this landmark invention the post modern civilization has entered into a new era “The Era of Molecular Farming”. In agricultural literature conventional farming is considered as the practice of producing commercial goods in a living system. The fine line of difference between conventional farming and molecular farming is in molecular farming manipulation of the living (expression) system at the molecular level is the principle strategy for commercial production of goods. So in technical terms we can define molecular farming as the practice of using a living system partially or as a whole in the form of bio reactors for the production of commercial products via recombinant DNA technology.

Therefore the living system as bioreactor and recombinant DNA technology are the two basic pre requisites for molecular farming. Technically a bioreactor is defined as a vessel that carries out a biological reaction and is used to culture aerobic cells for conducting cellular or enzymatic immobilization (Bhatia et al., 2015) whereas Recombinant DNA Technology is defined by the “the joining together of DNA molecules from different organisms and inserting it into a host organism to produce new genetic combinations that are of value to science, medicine, agriculture and industry.”( Nambisan et al., 2017)

Though the practical approaches of molecular farming greatly varies from product to product or from expression system to system it’s fundamental mechanism is common for all cases and it involves the following steps-

1. Isolation followed by the cloning of the gene of interest (GOI): GOI is the particular gene that belongs to the genome of a particular species responsible for expression of the product of interest (commercial product).  In a brief this primary step involves the isolation of DNA (using a standard protocol), extraction of GOI from the isolated DNA by using a standard restriction enzyme as molecular scissor and in-vitro amplification of the GOI by Polymerase Chain Reaction (PCR).

2. Transferring the GOI into a host species (species that received the foreign GOI) by direct or indirect method of gene transfer followed by integration of the GOI into the host genome using DNA ligase the molecular glue.

3. Growing of the genetically modified or transformed host species in vitro or in vivo.

4.Recovering of biomass followed by downstream processing to obtain the desired product in the purest form possible.

Molecular farming can be characterized by a great variation in the expression system (host). Expression systems may vary from unicellular prokaryotic bacterium to higher eukaryotes like plants or animals. Each expression system has it’s own pros and cons and in our next paragraph we’re going to have a glance on various expression systems with their pros and cons.

A. Bacteria as a host: In case of bacteria as a host species the only advantage is –

1. It is an ideal system for the production of small, aglycosylated proteins like insulin.

whereas having limitations like –

1.Due to the absence of eukaryotic translational and post translational machineries unable to produce higher proteins like antibodies.

2. Low scalability accompanied by higher cost of production.

3. Higher risk of contamination of the product by bacterial endotoxin.

B. Animal based system – When an animal cell or the whole animal functions as an expression system we have certain advantages like-

1. Due to the presence of eukaryotic translation and post translational machineries production of higher proteins is possible.

2. The cost of production is relatively less than the bacterial system.

But the limitations are-

1. Legal and ethical issues associated with animal trials.

2. Delicate nature of the animal cells due to the absence of the cell wall.

3. Chances of contamination of the final product by carcinogenic onco genes or human pathogens.

C. Plant based system: Due to numerous advantages in contrast to limited cons usually a plant based system is considered as the most efficient one among others. Here advantages are-

1. A versatile, easier and ideal for production of higher proteins by using the translational and post translational machineries of the higher plants.

2. Lowest production cost.

3. Contamination chances are negligible due to the absence of bacterial endotoxin, human pathogens or onco genes in plants.

Though the plant based method is the most ideal one yet we cannot nullify the hazardous effects of trans gene and trans protein pollution. So our approaches should be aimed at neutralising every possible chance of trans gene and trans protein pollution for the shake sustainable development and a better future of this globe.