ABSTRACT
Microalgae represent a remarkably diverse, yet largely unexploited resource. Currently, the only commercially established products from algae are whole algal extracts from species such as Chlorella that are marketed as a health food and as feed for aquaculture, or a few high-value biochemicals purified from microalgae such as (3-carotene from Dunaliella salina, astaxanthin from Haematococcus pluvialis, and the long-chain polyunsaturated fatty acid docosahexaenoic acid from 140the heterotrophic alga Crypthecodinium cohnii (Borowitzka 2013; Leu and Boussiba 2014). These species are essentially wild isolates and, as such, are not adapted to intensive cultivation as monocultures and to the high productivities required for their exploitation in industrial biotechnology. In the absence of a controllable sexual cycle for most microalgal species that would allow the combining of desirable traits and the removal of unwanted alleles (as used in the breeding of crop varieties and livestock), “algal domestication” has simply relied on bioprospecting for superior natural isolates or the use of mutagenesis to select for improved phenotypes (e.g., Jin et al. 2003; Chekanov et al. 2014). Both strategies are somewhat limited in that they offer only incremental improvements, and the latter approach is confounded by the accumulation of additional, deleterious mutations within the selected strain (Bonente et al. 2011).
