Economical production of algal commodities (food, feed, and fuels) requires reusing cultivation water to reduce operating costs. While some algae strains show growth inhibition in reused water, other strains appear unaffected. Reusing water to grow different strains (i.e., crop rotation) could potentially improve overall biomass production compared to water reuse with the same strain by reducing accumulation of strain-specific waste products, limiting carryover of population-specific pathogens such as viruses, and introducing bacteria that degrade residual organic matter. Here, batch culture experiments tested the effects of reused cultivation water from the self-inhibiting diatom Staurosira sp. C323 on the diatom Navicula sp. SFP and green alga Chlorella sp. D046, as well as their microbiomes. Navicula sp. and Chlorella sp. grew well in Staurosira sp. reused water, indicating that previously observed self-inhibition was likely specific to this Staurosira strain. While algal microbiomes were not significantly different between controls and reused water treatments, specific bacteria taxa were differentially abundant in reused treatments, suggesting that some taxa responded to compounds remaining in the reused water. Results suggest that algae growth responses in reused water may depend largely on strain-specific factors, and that crop rotation can support biomass production.
Loftus SE, Hunt DE, Johnson ZI (2020). Reused cultivation water from a self-inhibiting alga does not inhibit other algae but alters their microbiomes. Algal Research 51: 102067. DOI: 10.1016/j.algal.2020.102067