Large-scale algal culture systems: the next generation.

The large scale commercial culture of microalgae for the production of health foods, for aquaculture feeds and for high value fine chemicals such as iS-carotene is a well established biotechnology. Other microalgal products close to commercialisation are astaxanthin (Borowitzka, M.A., 1992b) and essential long chain polyunsaturated fatty acids such as docosahexaenoic acid (Martek, USA pers. com). The discovery of a range of unique biologically active substances with anti-neoplastic, anti-viral and anti-fungal activity produced by several microalgae, especially cyanobacteria, provides a further range of potentially valuable algal products (Knubel et al., 1990; Patterson et al., 1991, 1993) and studies to optimise production of these are already under way (e.g. Patterson & Bolis, 1993). Furthermore, progress is being made in genetic engineering of microalgae (Blankenship & Kindle, 1992; Davies et al., 1992; Gunson et al., 1993) and in the next few years it is likely that transgenic algae will also be used to produce selected chemicals.