Indole-3-butyric acid mediated growth and biochemical enhancement in three Selenastracean green microalgae under limited supply of nitrogen source

The effects of Indole-3-butyric acid (IBA) supplementation in combination with nitrogen limitation on the biomass, biochemical and fatty acid composition of three selenastracean microalgae were studied. In the algae tested, nitrogen deficiency alone resulted in lower biomass output, whereas supplementation with 0.075 mM IBA resulted in increased biomass production on Selenastrum capricornutum (679 mg L-1), Ankistrodesmus falcatus (521 mg L-1) and Kirchneriella obesa (361 mg L-1) than their respective controls. The chlorophyll content of the algae showed a negative correlation with IBA dosage. Whilst it could significantly stimulate carotenoid biosynthesis in S. capricornutum and nitrogen limited (NL) alone, it influenced carotene production in both A. falcatus and K. obesa. Among the treatments, NL+ 0.075 mM IBA markedly increased the total lipid content to 1.2-fold in S. capricornutum , 0.81-fold in A. falcatus and 0.35-fold in K. obesa, with higher lipid productivity than control. NL+ 0.05 mM IBA significantly increased the amount of saturated fatty acids and NL+ 0.075 mM IBA significantly increased the amount of unsaturated fatty acids in all members of the Selenastraceae family under study. Thus, the study promises the importance of Selenastraceae members as a valuable feedstock for various process industries.

Automated summary

This study investigated the effects of Indole-3-butyric acid (IBA) supplementation combined with nitrogen limitation on the biomass, biochemical and fatty acid composition of three selenastracean microalgae. The results showed that IBA supplementation increased the biomass production and influenced the synthesis of chlorophyll and carotenoids. The combination of nitrogen limitation and IBA significantly increased the lipid content and provided valuable feedstock for various industries.