Abstract
The green microalga Haematococcus pluvialis accumulates astaxanthin, a potent antioxidant pigment, as a defense mechanism against environmental stresses. In this study, we investigated the technical feasibility of a stress-based method for inducing astaxanthin biosynthesis in H. pluvialis using electric stimulation in a two-chamber bioelectrochemical system. When a cathodic (reduction) current of 3 mA (voltage: 2 V) was applied to H. pluvialis cells for two days, considerable lysis and breakage of algal cells were observed, possibly owing to the formation of excess reactive oxygen species at the cathode. Conversely, in the absence of cell breakage, the application of anodic (oxidation) current effectively stimulated astaxanthin biosynthesis at a voltage range of 2–6 V, whereas the same could not be induced in the untreated control. At an optimal voltage of 4 V (anodic current: 30 mA), the astaxanthin content in the cells electro-treated for 2 h was 36.9% higher than that in untreated cells. Our findings suggest that electric treatment can be used to improve astaxanthin production in H. pluvialis culture if bioelectrochemical parameters, such as electric strength and duration, are regulated properly.
Highlights
Published: 8 April 2021Astaxanthin (3,3’-dihydroxy-β-carotene-4,4’-dione) is a common high-value ketocarotenoid pigment (~US $7150 per kg) involved in various metabolic functions, including anti-oxidative, anti-inflammatory, and immune-stimulatory functions [1,2]
In connection with the previous study on algal lipids [19], in this study, we aimed to investigate the technical feasibility of using electric stimulation to improve astaxanthin accumulation in H. pluvialis using a two-chamber bioelectrochemical system
To enhance astaxanthin production in H. pluvialis cells, 1 mM nitrate was used as the nitrogen source
Summary
Published: 8 April 2021Astaxanthin (3,3’-dihydroxy-β-carotene-4,4’-dione) is a common high-value ketocarotenoid pigment (~US $7150 per kg) involved in various metabolic functions, including anti-oxidative, anti-inflammatory, and immune-stimulatory functions [1,2]. Various stress-inducing conditions, such as nutrient starvation [7,8], exposure to intense light [9,10], high temperatures [11,12], high salinity [13,14], and nanomaterial addition to culture [15], have been applied to increase the content and productivity of algal astaxanthin. Nitrogen-nutrient depletion has been employed extensively for effective astaxanthin induction in H. pluvialis cultures [2,16]. This approach is time-consuming and associated with a risk of biocontamination from external sources; it significantly reduces the biomass productivity of H. pluvialis [17]. The development of an effective astaxanthin induction strategy remains a major challenge in H. pluvialis biorefinery approaches
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