Establishing new microbial cell factories for sustainable bioprocesses

The demands of modern society are increasing pressure on natural resources while creating the need for a wider range of products. There is an interest in developing bioprocesses to meet these demands, with conversion of a variety of waste materials providing the basis for a sustainable society. The application of biological catalysts which can convert a variety of substrates to an array of
desirable products has been demonstrated in both ancient bioprocesses and modern industrial biotechnology. In recent times, focus has been on a limited number of “model” organisms which have been extensively exploited and developed. Systems biology approaches can be applied with these well studied strains, where considerable physiological data has been obtained, genome sequences are known and genetic tools have been developed. With the necessity of considering a wider array of substrates and the need for new types of products, it may be interesting to look to less domesticated strains and towards more non-conventional hosts in the development of new bioprocesses. This approach demands thorough physiological characterization as well as establishment of tools for genetic engineering if new cell factories are to be exploited through application of systems biology tools. Here two potential cell factories for the conversion of glycerol are described: Pachysolen tannophilus and Yarrowia lipolytica. These organisms exhibit considerable potential; producing ethanol and 1,3-butanediol (P. tannophilus) and organic acids, lipids and polyols (Y. lipolytica). In addition to their product range the strains are also capable of converting carbon sources found in a range of sustainable feedstocks.