David Stuart, Bonnie McNeil and Xiadong Liu.
Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada.
Long chain fatty alcohols are chemicals that are widely used in the cosmetic, pharmaceutical, food, and chemical industries. Their amphiphilic nature makes them effective emulsifiers, emollients, surfactants and platform chemicals. The fatty alcohols hexadecanol and octadecanol do not occur naturally in any appreciable quantity. Rather, these chemicals are primarily produced through the reduction and hydrogenation of palm oil in Asia. Deforestation and loss of biodiversity incurred by the expansion of palm plantations has had a profound impact upon the environment. Additionally, the use of palm oil as a feedstock for chemical synthesis diverts this oil away from availability as a food and cooking oil.
We have engineered a microbial strain to produce hexadecanol and octadecanol from C6 and C5 sugars and cellulosic hydrolysates of wheat straw and softwood. We have also applied this technology to the conversion of C1 compounds into fatty alcohol and other lipid products. The product yields have been significantly improved through a fermentation strategy that promotes the secretion of the fatty alcohol products into the fermentation medium. The procedure used resulted in 85% of the product being secreted into the fermentation medium and increased the overall yield. We observe a clear preference for the secretion of hexadecanol over octadecanol. Secretion of the product from the cells reduces its intracellular accumulation, thereby promoting increased product synthesis. Additionally, secretion of the fatty alcohol from the cells profoundly simplifies collection and purification of the products.
This technology has the potential to free North American industries from a dependence on Asian palm oil as a source of fatty alcohols. Thus alleviating concerns about supply chain security, environmental impact, and the carbon cost associated with current production procedures. Additionally, it caters to the growing demand for “palm free” products.