Enhanced astaxanthin production by oxidative stress using methyl viologen as a reactive oxygen species (ROS) reagent in green microalgae Coelastrum sp.

Microalgae are known to be a potential resource of high-value metabolites that can be used in the growing field of biotechnology. These metabolites constitute valuable compounds with a wide range of applications that strongly enhance a bio-based economy. Among these metabolites, astaxanthin is considered the most important secondary metabolite, having superior antioxidant properties. For commercial feasibility, microalgae with enhanced astaxanthin production need to be developed. In this study, the tropical green microalgae strain, Coelastrum sp., isolated from the environment in Malaysia, was incubated with methyl viologen, a reactive oxygen species (ROS) reagent that generates superoxide anion radicals (O2-) as an enhancer to improve the accumulation of astaxanthin. The effect of different concentrations of methyl viologen on astaxanthin accumulation was investigated. The results suggested that the supplementation of methyl viologen at low concentration (0.001 mM) was successfully used as a ROS reagent in facilitating and thereby increasing the production of astaxanthin in Coelastrum sp. at a rate 1.3 times higher than in the control

Improvement of astaxanthin production in coelastrum sp. by optimization using taguchi method

Background and Objective: Astaxanthin is a keto-carotenoid pigment known as one of the most valuable compounds with great potentials in the market. It has widely been used in nutraceutical, pharmaceutical, cosmetics and food industries due to its strong antioxidant activity. Green microalgae seem as promising natural sources in production of astaxanthin. The aim of this study was to optimize astaxanthin production in Coelastrum sp. to overcome low productivity of microalgae. Materials and Methods: This study was carried out using experimentally statistical technique and Taguchi method to find optimum conditions for maximizing production of astaxanthin in green microalgae, Coelastrum sp. Effects of nutritional (carbon and nitrogen) and environmental (light and salinity) factors on biomass and astaxanthin production were investigated. Experiments were carried out for light intensity (250-550 μmol photons m-2 s-1), salinity using sodium chloride (1.0-3.0 g l-1), carbon source using sodium acetate (0.5-2.0 g l-1) and nitrogen source using sodium nitrate (0.1-0.3 g l-1). Results and Conclusion: Results showed that optimum conditions of astaxanthin production in Coelastrum sp. included 250 μmol photons m-2 s-1 of light intensity, 3 g l-1 salinity, 0.5 g l-1 carbon and 0.1 g l-1 nitrogen with a maximum yield of astaxanthin (14.44 mg l-1), which was 2-fold higher than that before optimization. This optimization resulted in high quantities of astaxanthin production using optimization of conditions that affected production yields of astaxanthin from Coelastrum sp

Astaxanthin production by tropical microalgae strains isolated from environment in Malaysia

Astaxanthin is one of the most important secondary metabolites with superior antioxidant property and is widely applied in nutraceuticals and pharmaceuticals industry. Recently, the production of astaxanthin from natural source has been mainly focused on the green microalgae, Haematococcus pluvialis, as it can accumulate large amounts of astaxanthin and its esters. However, the slow growth with low biomass yield and easy contamination by other fast-growing organisms are the main problems faced by H. pluvialis. In this study, the preliminary study on growth characteristic and amount of astaxanthin by tropical microalgae strains isolated from environment in Malaysia was reported. Two newly isolated microalgae including Acutodesmus obliquus and Coelastrum sp. were compared under various stress inductive conditions to identify the microalgae culture that can accumulate high amount of astaxanthin. The objective of this study is to compare and characterise astaxanthin accumulation using different species of green microalgae as mentioned above under different stress conditions. Findings of the preliminary studied indicated that the exposure of microalgae culture to high light intensity and nitrogen starvation in mixotrophic culture is a potential inducer of high amount of astaxanthin production. Among the two microalgae studied, Coelastrum sp., exhibited the highest tolerance to stress conditions. Outcomes of this work have shown that, astaxanthin produced in Coelastrum sp. is the most comparable to H. pluvialis and can be the potential alternative to current astaxanthin production

Improvement and screening of astaxanthin producing mutants of newly isolated Coelastrum sp. using ethyl methane sulfonate induced mutagenesis technique

Natural astaxanthin is known to be produced by green microalgae, a potent producer of the most powerful antioxidant. To increase the productivity of astaxanthin in microalgae, random mutagenesis has been extensively used to improve the yield of valuable substances. In the presented work, a newly isolated Coelastrum sp. was randomly mutagenized by exposure to ethyl methane sulfonate and further screened using two approaches; an approach for high growth mutant and an approach for high astaxanthin producing mutant with a high-throughput screening method using glufosinate. Among these, mutant G1-C1 that was selected using glufosinate showed the highest of total carotenoids (45.48±1.5 mg/L) and astaxanthin (28.32±2.5 mg/L) production, which was almost 2-fold higher than that of wild type. This study indicates that random mutagenesis via chemical mutation strategy and screening using glufosinate successfully expedited astaxanthin production in a mutated strain of a Coelastrum sp