Bromoform, mycosporine-like amino acids and phycobiliprotein content and stability in Asparagopsis armata during long-term indoor cultivation

Abstract

As the commercial use of seaweed for natural product extraction calls for abundant, uniform biomass, this study focused on the production and the variability of the harvested biomass of valuable compounds produced by a commercially relevant red algal species, Asparagopsis armata. Its tetrasporophyte stage was retrieved from two Irish localities and grown for over 2 years in indoor cultures at 13 °C and 17 °C, and bromoform, mycosporine-like amino acids and phycobiliprotein contents were monitored over time. Growth rates at different temperatures were specific to isolates, and one isolate failed to grow at 17 °C. All compounds of interest were detected by the end of the 2-year cultivation period, and most of them were produced at an exponential rate at 13 °C but not at the higher temperature. At 13 °C, bromoform reached concentrations of 10.00 ± 0.55 mg g−1, total mycosporine-like amino acids of 2.65 ± 0.10 mg g−1, phycoerythrin of 11.46 ± 0.35 mg g−1 and phycocyanin of 72.13 ± 1.74 mg g−1 in Irish isolates. The observed variability in compound content was statistically significant but not large enough to impede commercial utilization. Bromoform content in cultivated samples was almost 6-fold higher than in field-collected samples though natural bromoform variability remains to be elucidated. Our findings suggest that the tetrasporophytic phase of A. armata is a suitable candidate for indoor cultivation; abundant and homogeneous biomass composition can be obtained which can be further optimized by growth temperature.