Sampling Frequency Is a Key Factor to the Efficient Actuation of the Phytohormones in the Increase of Biomass and Macromolecules Production by Spirulina (Arthorspira)

Abstract

Application of microalgae in industries is limited by their low biomass production and low macromolecule content. Phytohormones are being studied to solve these problems, however is necessary to define conditions that enhance the results for this kind of cultivation strategy. The increasing of the contact time between substances and cells can be a factor of the improvement in the phytohormone uptake by microalgae. We hypothesize that by decreasing the sampling frequency for monitoring culture parameters, we would also be interfering less in the uptake of phytohormones by microalgae. Therefore, the present study aimed to investigate the influence of sampling frequency on the production of biomass and biomolecules of Spirulina sp. LEB 18 in cultivations supplemented with trans-zeatin and indole-3-acetic acid (IAA). Treatments with lower sampling frequency and supplementation of 1 mg L− 1 IAA enhanced biomass accumulation by 75 %, carbohydrate content by 50 %, and protein content by 30 % as compared to control experiment daily sampling. In addition, sampling every 10 days with 0,01 mg L− 1 IAA supplementation increased the lipid content by 51 % as compared with the experiment without phytohormone and daily sample removal. Therefore, we developed a new strategy to supplement phytohormones and improve microalgal production. This investigation presented a cultivation system efficient, which can be easy to implement in industries because of no need to change the operational aspects of the cultivation. Furthermore, the strategy will can be very useful to enhance the production capacity of microalgae on a large-scale.