Optimization of Cultivation Conditions for Tetraselmis striata and Biomass Quality Evaluation for Fish Feed Production

The marine microalgae Tetraselmis striata was cultivated in drilling waters with different salinities. Growth substrate optimization was performed while the effects of different pH, temperature, photoperiod and CO2 flow rate on biomass productivity and its composition were studied. Results showed that the strain grew better in 2.8% drilling waters employing the fertilizer Nutri-Leaf together with aHCO(3). A pH value of 8 resulted in high biomass productivity (79.8 mg L-1 d(-1)) and biomass composition (proteins 51.2% d.w., carbohydrates 14.6% d.w., lipids 27.8% d.w. and total chlorophylls 5.1% d.w.). The optimum cultivation temperature was found to be 25 +/- 1 degrees C which further enhanced biomass productivity (93.7 mg L-1 d(-1)) and composition (proteins 38.7% d.w., carbohydrates 20.4% d.w., lipids 30.2% d.w., total chlorophylls 5.1% d.w.). Photoperiod experiments showed that continuous illumination was essential for biomass production. A 10 mL min(-1) flow rate of CO2 lead to biomass productivity of 87.5 mg L-1 d(-1) and high intracellular content (proteins 44.6% d.w., carbohydrates 10.3% d.w., lipids 27.3% d.w., total chlorophylls 5.2% d.w.). Applying the optimum growth conditions, the produced biomass presented high protein content with adequate amino acids and high percentages of eicosapentaenoic acid (EPA), indicating its suitability for incorporation into conventional fish feeds. In addition, this study analyzed how functional parameters may influence the uptake of nutrients by Tetraselmis.

Automated summary

This study cultivated Tetraselmis striata, a marine microalgae, in drilling waters with different salinities and optimized the growth substrate. The effects of pH, temperature, photoperiod, and CO2 flow rate on biomass productivity and composition were investigated. The results showed that the strain had better growth in 2.8% drilling waters with the fertilizer Nutri-Leaf and aHCO(3). A pH of 8 and a temperature of 25°C were found to be optimal for high biomass productivity and composition. Continuous illumination and a CO2 flow rate of 10 mL min(-1) were essential for biomass production. The produced biomass had high protein content, suitable amino acids, and high levels of eicosapentaenoic acid (EPA), making it suitable for incorporation into conventional fish feeds. This study also analyzed the impact of functional parameters on nutrient uptake by Tetraselmis.