When the word ‘plant’ comes to mind, one associates it to a number of its uses such as fruits, vegetables, decoration, clothes, medicines, prevention of soil erosion, photosynthesis for Oxygen production – to name a few. However, when the tobacco plant comes to mind, one most likely associates it with production of cigarettes, cigars, shisha and potentially cancer. Considering the current worldwide applications of various plants, such associations to the tobacco plant are not entirely unreasonable. Tobacco is known to be grown in at least 124 countries, occupying 3.8 million hectares of agricultural land (1). In 2011, approximately 7.6 million metric tons of tobacco was produced for use in the smoking and related industry (2). However, this plant could be greeted with much positivity if its potential for alternative applications were explored.
Application in Biotechnology Research
Tobacco plants have been extensively used as model plants in Genetic Engineering research owing to their extensively studied genome, easy propagation and well-developed transformation methods (3) (4). Furthermore, they have high biomass yields (in excess of 40 tons of fresh leaves weight/acre based on multiple mowing per season and up to one million seeds produced per plant (5)) and rapid scalability, making them suitable for plant-based molecular pharming (a technique of protein production in a genetically modified host) (4) (6). Among the several companies that have been established to exploit such technology, a few are listed below:
- Medicago (7) has developed a tobacco based technology – Proficia™ (8) – for development of vaccines and therapeutic proteins. Their products are at various stages of development, with one (targeting influenza) having completed phase 2 clinical trials (9)
- An EU funded project – Pharma Planta – produced an anti-HIV antibody using genetically modified tobacco plants okwhich completed phase 1 clinical trial (10) (11)
- Mapp Biopharmaceutical has developed an experimental drug to fight the recent outbreak of Ebola using tobacco based antibody production (12) (13) (14)
- Caliber Biotherapeutics applies its expertise in tobacco plant-based expression for manufacturing recombinant proteins targeting non-Hodgkin’s lymphoma, multiple myeloma, and breast cancers (15)
- Planet Biotechnology (16) developed CaroRx – an antibody based product for protection against tooth decay – using transgenic tobacco plants. The product is currently undergoing phase 2 clinical trials under a US IND (Investigational New Drug). (17) (18)
Application in the Biofuel Industries
Seeds: Tobacco seeds contain high quantities of oil – roughly 40% by weight (19), making them an attractive contender as a source of biofuel (20). However, due to the relatively lower yield of tobacco seeds when compared with other biofuel oil producers like the rapeseeds and soybean, researchers are also looking at modifying tobacco plants to increase the oil content of leaves; this has resulted in about 20-fold more oil in some instances (21) (22). Boeing, South African Airways and SkyNRG have collaborated to manufacture biodiesel from tobacco seed oil – firstly, to reduce aviation fuel price and secondly, to reduce the amount of carbon dioxide released (23).
Plants: The Lignocellulosic biomass from a plant is the most abundantly available raw material for the production of bio-fuels, mainly bio-ethanol (24). Tobacco produces approximately five dry tons of biomass per acre even after removal of potentially useful co-products. This material can be converted to energy or used as a high-nutrition animal feed (25). If converted to ethanol, each acre could produce approximately 335 gallons of ethanol at a rate of 67 gallons/ton of biomass (25).
Tyton BioEnergy Systems is currently working on genetically engineering tobacco plants to increase their sugar and oil content, thus allowing them to be used for both ethanol and biodiesel production (26).
Beyond Nicotine, other substances extractable from Tobacco plants
Tobacco is a plant within the Nicotiana genus of the Solanaceae family (27). Although more than 70 different species of tobacco are currently recognised, the chief commercial crop is Nicotiana tabacum; the more potent species Nicotiana rustica is also widely used around the world (28), owing to their high nicotine concentrations (1-3% and up to 9% respectively) (29). The predominance of these strains is largely a result of human selection. However, the tobacco plants contain a range of chemical compounds, apart from Nicotine, such as solanesol, tobacco proteins, pectin, organic acids which can be extracted as value added products (30). The quantities of these compounds vary significantly based on plant age, agricultural practises, soil type and nutrients, weather conditions, stalk position and harvesting procedures (31).
Solanesol: It is the starting material for many high-value bio-chemicals, including co-enzyme Q10 and Vitamin K analogues which is useful in the treatment of heart diseases, cancers and ulcers (32) (33). Zhejiang Yixin Pharmaceutical Co. Ltd., based in China, manufactures Tobacco extracted Solanesol (33). NewAgriculture Inc. also works on Solanesol extraction for use in pharmaceutical and nutraceutical products (25).
Proteins: Tobacco proteins are composed of about 10% Fraction 1 and 90% Fraction 2 proteins (30) They contain a well-balanced amino acids’ content and can be crystallized in to a pure powder which has no odour or taste (30). Fraction 1 proteins have been reported to exhibit a higher protein efficiency ratio (PER) than casein, the common standard for comparing the nutritional quality of proteins (34); they are most valuable for medical and pharmaceutical applications (30). The primary proposed use of these proteins is for kidney dialysis patients with dietary restrictions (30). Fraction 2 proteins are used in animal feed (30).
NewAgriculture Inc. is developing a technology for extraction of tobacco protein Rubisco (Fraction 1) to market for non-food industrial uses and will also pursue FDA recognition of the protein as a GRAS (Generally Recognized As Safe) to allow its sale as a food supplement (25).
Pectin: Increasing interest is being seen in the exploration of pectin extraction from tobacco plant cells for use in the chemical, pharmaceutical and/or food industry as a binding agent or filler (35) (36) (37).
Carboxylic acids: The major carboxylic acids in tobacco are citric, malic, oxalic and malonic, the composition in total of which can vary from c. 5% to 18% by weight of the plant for different Nicotiana strains and their cultivation conditions (31) (38). Various technologies are being looked at for extraction of these components, particularly citric and malic acids, for their application in the food industry (39) (40).
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