A Novel High-Yield Leaf Crop for Integrated Production of Bioproducts
Conventional tobacco is widely cultivated throughout the world. Biomass tobacco, without limitations of factors affecting quality for traditional tobacco products such as cigarettes, may have an even broader growing range than conventional tobacco. The widespread use of tobacco as a model system for plant biology and genetic engineering means that extensive information about the tobacco genome and the functions of many tobacco genes already exists. This body of knowledge is quite useful for development of innovative crops through incorporation of additional traits into 22nd Century’s genetically engineered reduced-alkaloid tobacco lines for more efficient, sustainable production of a variety of specific products.
North Carolina State University has demonstrated over four consecutive years of field trials that Verfola™, very low nicotine tobacco grown and handled as a forage crop, with multiple harvests from a single planting, produces about 50 tons per acre (fresh weight) of biomass per growing season in North Carolina. Higher volumes than those obtained in North Carolina may be achieved in geographical regions with longer growing seasons.
For every acre of tobacco biomass grown from tobacco with conventional nicotine levels, hundreds of pounds of toxic alkaloids including nicotine would have to be extracted, stored and disposed. 22nd Century’s very low nicotine tobacco lines alleviate this problem. One of 22nd Century’s short-term goals is to reduce nicotine levels in a tobacco biomass variety to the trace amounts found in related plants, such as green peppers, tomatoes and potatoes (Andersson et al. 2003; Sheen 1988).
Since tobacco biomass is a green leaf crop, protein production and quality are impressive. Total protein production is about 1 ton per acre (dry weight), half of which is soluble, extractable protein with an excellent balance of essential amino acids. A crystalline protein fraction, consisting of a protein involved in photosynthesis (Ribulose Bisphosphate Carboxylase-Oxygenase or “Rubisco”), can be easily prepared from tobacco. Purified Rubisco is a pharmaceutical grade protein that is tasteless, odorless, and colorless when mixed with water. With the exception of slightly lower levels of the amino acid methionine, Rubisco’s content of essential amino acids equals or exceeds that of the FAO [Food and Agriculture Organization (of the United Nations)] Provisional Pattern (Ershoff et al. 1978). Sugars, starches, cellulose and other components remaining after extraction of protein and/or other products can be used directly or by fermentation or pyrolysis for production of biofuels, such as ethanol, butanol, biogas and bio-oil, or industrial feedstocks.