nanochloropsis oculata

The nutritional value and special properties of Artemia have led to its use as a food and biological model in aquaculture. L-Carnitine supplementation stimulates the oxidation of fatty acids, increases nitrogen retention and resistance to environmental stress, and L-Arginine nutritional supplementation is effective in protein synthesis, nitric acid and growth hormone growth and survival. In this study, the effect of Nanochloropsis oculata micro algae enriched with L-carnitine and L-arginine supplements on growth, environmental stress, absolute fecundity and saturated fatty acid profile in Artemia feransiscana was investigated. L-carnitine and L-arginine were applied separately at concentrations of 0, 1, 10, 100 and 1000 mg/l. Artemia cysts under special hatching conditions and Napolius were fed with N. oculata microalgae with two states, enriched conditions and without enrichment (control treatment) separately in 30 days. The results were compared and it was shown that the highest saturated fatty acid (SFA) with nutritional treatment L-carnitine 10 mg/l and the lowest was in the control treatment. The highest mortality percentage of ammonia shock was related to rich treatment with 1 and 100 mg/l L-carnitine which showed a significant difference with the control treatment (p<0.05) and the lowest was related to 1 mg/l L-arginine treatment and control treatment. In hypoxia shock, the highest mortality percentage was observed in the diet with L-carnitine 1 and L-arginine 1 and 100 mg/l and the lowest in the diet with L-carnitine 10 mg/l, all of which showed a significant difference with the control treatment (p<0.05). In  adult Artemia breeders,  the lowest quality indicators  were related to L-carnitine treatment at all doses except 1000 mg/l and the highest were related to L-arginine treatment except 100 mg/l plus 1000 mg/l. L- carnitine that showed a significant difference with the control treatment (p<0.05) .The highest amount of absolute fecundity is related to the nutritional treatment rich in L-arginine 1000 mg/l and the lowest is the control treatment, which shows the positive effect of both supplements on increasing the absolute fecundity. Overall, the results showed that the use of the mentioned nutritional supplements with N. oculata microalgae in A. franciscana nutrition in specific doses can be effective in increasing production and quality in the aquaculture industry. Therefore, according to the environmental stress conditions, improving the fecundity performance and achieving a higher quality index, the optimal doses of each supplement can be used.

In this study, in the first phase, the optimum extraction conditions of the extract (temperatures of 50, 70 and 90°C, duration of 20, 70 and 120 min and the ratio of dry matter to solvent of 10, 20 and 30 mL/g) algae Nannochloropsis oculata was examined. The antioxidant activity of the algal extracts in the first phase was calculated by measuring the radical inhibitory power of DPPH (2, 2-diphenyl-1-picrylhydrazyl). In the second phase, the effect of adding the hydroalcoholic extract of N.oculata at 0, 350, 550 and 1000 mg/L in reducing the antioxidant activity of tuna oil was investigated. Treatment time of 120 minutes, temperature of 70°C, and dry matter to solvent ratio of 30 ml/g had the highest efficiency of the extract in terms of free radical scavenging.. The storage time was 56 days and the parameters of peroxide, TBA, and p-anisidine was measured in the tuna oil on 0, 7, 14, 21, 28, 35, 42, 49 and 56 days. The highest antioxidant power was measured at 1000 mg/L (85.45±0.55%). The index values ​​of peroxide, TBA, and p-anisidine of the tuna oil had an increasing trend with increasing in the storage time and reached its highest levels on day 56. The control group had the highest and the fish oil treatment 1000 mg/L hydrochloric extract of N. oculata had the lowest levels of oxidative indices. According to the results of treatments receiving hydroalcoholic extract of algae Nanochloropsis protective factor and antioxidant power compared to BHT, which shows that algal extract in all three concentrations of 350, 550 and 1000 mg/L can be well replaced with synthetic compounds.

Due to small size of microalgae and low concentration in the culture medium, cost-efficient harvesting of microalgae is a major challenge. In the present study, the possibility of using electro-flocculation technique (direct current) for harvesting of microalga Nanochloropsis oculata biomass from the culture broth was investigated. The microalga biochemical composition and chlorophyll a content, and viability of N. oculata cells were determined on concentrated microalgal cells after 10 days of electro-flocculation. The results from the biochemical analysis and chlorophyll a measurements indicated that N. oculata flocculated cells showed no sign of degradation in biochemical composition and chlorophyll a from electroflocculation as compared to control. Moreover, the results clearly showed that, flocculation efficiency improved with increasing direct current. Between 3-10 V; the flocculation efficiency was as high as 85-97.0%. The highest flocculation efficiency, 97.0%, was obtained at 10 V, of 30 minutes and with short settling time of 2 hours. The cell viability obtained in flocculation with direct current (3-10 V) showed cells in good shape and indistinguishable from nonflocculated cells when viewed by light microscopy. This study demonstrated that electroflocculation is an effective method to flocculate N. oculata cells; therefore, it could be considered as a cost-effective alternative for preparing microalgal concentrates for the aquaculture industry and hatcheries.