Michael A. Borowitzka

Establishing new bio-based sectors requires effective implementation of innovation and production supply chains, often competing with established synthetic technologies. Our analytical model conceptualizes the competition between an incumbent industry and a competitive fringe, each producing differentiated products. Although motivated by the beta-carotene case, the model is versatile and applicable to other contexts involving novel products entering markets dominated by established technologies. Developed by university researchers and commercialized by start-ups, natural beta-carotene was eventually integrated into major synthetic corporations. Initially niche and costly, it gained market competitiveness through innovation and expanded applications, driving technological advancements and significantly benefiting the broader algae-based industry.

To produce microalgal biomass, either as a product in its own right or as source of extracted chemical compounds, or to use algae as a means of treating wastewaters, the algae need to be grown in some sort of container or vessel, often called an algal bioreactor.

The diversity of algal bioreactor designs is almost as great as the diversity of the algae that are grown in them, but the reactors can be broadly classified into “open” and “closed” bioreactors. Open bioreactors include the shallow extensive open ponds used to grow Dunaliella salina in Australia, the high-rate oxidation ponds used in wastewater treatment and the widely used raceway ponds of various designs. In closed reactors, the algal culture is fully contained within a vessel, and they are further sub-divided into reactors where the algae are exposed to light (photobioreactors) or dark reactors (fermenters). Culture volume can vary from laboratory scale (culture volume up to ∼500L) to commercial-scale (up to ∼106–109L).

In addition to the current uses of algae as food and as sources of pigments and polysaccharides, there is potential for the further use of algae as sources of additional specific biomolecules. In addition to this, there is the possibility of the use of alga in a wide variety of processes such as bioenergy (production of liquid fuels and algal biophotovoltaic generation of electricity), removing pollutants from wastewater, and the production of plant growth enhancers and crop protection materials. The eventual commercialisation of these requires the processes to be scalable and economical. The targeted use of algae, other than as food sources, is less than 100 years old and our knowledge of algal biology, physiology and chemistry is still growing and only a very small number of algal species have been studied in detail. One of the main limitations is the need for more reliable, lower cost and larger-scale algae production systems and their development, in turn, requires a good understanding of basic algal biology and life histories. In addition, more work is needed on increasing the efficiency of light utilisation in photosynthesis and hence in growth.

A descriptive model of calcification in the coralline red algae is integral to understanding their contributions to marine geochemistry, the responses of seascapes to global change, and their own evolution and ecology. Yet, the development of a holistic model of this process has so far been limited by the intrinsic challenge of assembling multiple lines of experimental and observational evidence from varied disciplines. To resolve this synthetic gap, we integrated ultrastructural, geochemical, biochemical and physiological data against a backdrop of anatomy and morphogenesis, which provide context for the localized process at play within the algal thallus. This synthesis represents a comprehensive description of calcification in the coralline red algae.

Botryococcus braunii CCAP 807/2 has been studied intensively for biofuel production due to its high hydrocarbon content. This strain is also capable of producing high value carotenoids. The aim of the study was to analyse the carotenoid production of B.braunii 807/2 under different growing conditions, first, by using different media and light intensities in indoors, and next, to examine the carotenoid composition between green, intermediately pigmented and red B. braunii grown in indoors and outdoors. The alga was cultured indoors under two different light intensities (100 and 500 μmol photons m−2 s−1) using three different media: a control with complete modified CHU 13 medium, modified CHU 13 without N and modified CHU13 without N + 2Fe. All cultures were grown at 25 °C with 12:12 h light:dark cycle and were mixed with magnetic stirrers. For the determination of carotenoid composition at different stages, the green, intermediately pigmented and red cells were collected from indoor and outdoor cultures and analysed for their carotenoid composition using HPLC. The cultures grown at high light intensity reached the highest biomass yield at 0.6 g L−1 on day 16, whereas their counterparts at low light intensity took 30 days to reach the same biomass yield. The carotenoid production of B. braunii 807/2 at high light intensity increased up to twofold in 2 days compared to the ones grown at low light. Botryococcus braunii 807/2 accumulates lutein, canthaxanthin and astaxanthin and β,β-carotene as the main carotenoids. Whilst lutein was the major carotenoids of the green/intermediate cells, canthaxanthin and astaxanthin were the predominant carotenoids of the red cells under indoor and outdoor culture, respectively. This study suggests that Botryococcus braunii 807/2 is a potential candidate for the production of lutein and/or astaxanthin. It accumulates a high amount of lutein when grown under optimum conditions and a high amount of astaxanthin when grown under sub-optimum conditions outdoors.

Diatoms are of great interest for large-scale cultivation due to their high lipid content. The ability to grow over a wide range of salinities is also of great advantage. We studied the effect of temperature and salinity on the growth, lipids and fatty acid profiles of a newly isolated halophilic diatom Amphora sp. MUR 258. Amphora sp. MUR 258 is unusual in that it grows over a wide range of temperatures (24–35 °C) and salinities (7–12% (w/v) NaCl). The highest specific growth rate (SGR; 0.607 ± 0.017 day−1) was achieved at 7% NaCl at 35 °C, and the lowest SGR (0.433 ± 0.087 day−1) was obtained at 9% NaCl at 25 °C. The cells contained more lipids in the exponential phase, except when grown at 12% NaCl where the lipid content was higher in the stationary phase. The alga achieved its highest lipid content (57.69 ± 2.039% ash-free dry weight (AFDW) when grown at 7% NaCl at 25 °C and the lowest (34.43 ± 3.955% AFDW) obtained at 12% NaCl at 35 °C. The highest biomass productivity (0.171 ± 0.017 gAFDW L−1 day−1) and the lipid productivity (0.062 ± 0.017 gAFDW L−1 day−1) were achieved when the Amphora were grown at 9% NaCl at 35 °C and 7% at 25 °C, respectively. Irrespective of the growth conditions, the predominant fatty acids of Amphora sp. MUR 258 were palmitic acid (C16:0), stearic acid (C18:0), palmitoleic acid (C16:1) and oleic acid (C18:1), as well as low quantities of eicosapentaenoic acid (C20:5).

The science of seaweeds (i.e., phycology, the study of algae including macroalgae) is many centuries old. Indeed, some of the earliest taxonomic names using the binomial system, as applied by Linnaeus to any living thing were given to common seaweeds (i.e., Fucus). The taxonomic work was soon followed by studies on their biology (structure and reproduction), physiology, ecology (zonation, ecosystem services) and distributions (phycogeography)...