Phytohormone supplementation mediated enhanced biomass production, lipid accumulation, and modulation of fatty acid profile in Porphyridium purpureum and Dunaliella salina cultures

An economically feasible and sustainable microalgal biorefinery needs to develop culture stra­
tegies to maximize biomass productivity and accumulate important metabolites in select micro­
algae. The present study evaluated the effect of indole-3-acetic acid (IAA) and diethyl amino ethyl
hexanoate (DAH) on two marine microalgae of commercial importance, viz., Porphyridium pur­
pureum and Dunaliella salina. The photosynthetic efficiency, biomass productivity, and accumu­
lation of PUFA rich lipids in P. purpureum and D. salina were studied. The microalgal cultures
supplemented with both the phytohormones at lower concentrations (10-7 to 10-8M) showed an
enhanced biomass production (2 to 3.5 fold increase), lipid content (up to 1.4 fold increase), and
PUFA content (1 to 2 fold enhancement) at p < 0.001, compared to control cultures. The
maximum photosynthetic efficiency (Fv/Fm) of IAA and DAH supplemented microalgal cultures
increased up to 2.2 fold with up to a two-fold reduction in the average antenna size (ABS/RC) and
dissipation energy (DI0/RC). The study suggests that supplementing the P. purpureum and
D. salina cultures with phytohormone could effectively enhance the biomass production and
accumulation of PUFA rich lipids.