Elicitation of bioactive compounds from Microalgae

Abstract

This research aims to discuss and compare various elicitation techniques to increase bioactive compounds production by microalgae. Microalgae produce range array of biologically active metabolites that have attracted the attention due to their extensive health benefits. Since these metabolites are produced in low amounts or in response to stress conditions, various elicitation techniques were investigated to increase their production. Ten studies were selected, and different elicitation strategies were analysed. Studies showed that the application of biotic or abiotic elicitors could be an effective strategy for bioactive compounds accumulation. It was found that salicylic acid significantly enhanced alkaloid accumulation (p< 0.05) in A. platensis. The use of DA-6 considerably upregulated the expression of astaxanthin responsible genes. Studies indicated that the slow growth of some microalgal species is a major limitation of the high accumulation of metabolites. It was found that the periodic electrical treatment of 100mA had a promoting effect on H. pluvialis growth and its astaxanthin production. The two-stage cultivation technique resulted in high production of N. laevis biomass and fucoxanthin of (17.25 g/L) and (16.5 mg/L·d), respectively. Shifting from low to high light showed a significant increase in phenolic compounds production (p<0.01) by Spirulina platensis. The findings revealed that the production of the metabolites by microalgae can be significantly affected by different factors such as light, biomass concentration and cultivation modes. Thus, suitable cultivation conditions for both microalgal growth and metabolites production during the elicitation should be considered. Future evaluation of further hormonal elicitors is of interest