MICROALGAE FROM THE PROVIAPT CLOSED PHOTOBIOREACTOR SYSTEM FOR AQUACULTURE

Proviron has developed a closed photobioreactor system for the growth of different algae species.  The unique cultivation system allows growing the selected microalgae in high purity, free of contaminating algae or predators and with very low bacterial load. The harvested algae are concentrated and finally freeze dried. Because of the unique processing, the biomass is easily suspended in water and results in single cell dispersed algae which do not sediment and hence do not foul the larval tanks.

The two species which are currently produced are Nannochloropsis sp. and Isochrysis T-ISO. Both marine algae species have an interesting nutritional profile, especially regarding ω-3 fatty acids and carotenoids. They are a rich source of pigments such as β-carotene, violaxanthin, zeaxanthin, …. The overall high carotenoid content combined with elevated levels of polyphenols and α-tocopherols provides these algae with high antioxidant capacities (ranging between 30-40 trolox equivalents/g dry biomass in TEAC assay). Nannochloropsis accumulates high levels of the ω-3 poly-unsaturated fatty acid eicosapentaenoic acid (EPA), predominantly present in readily bioavailable polar lipid forms, whereas Isochrysis tends to accumulate high levels of docosahexaenoic acid (DHA).

Nannochloropsis sp. is one of the most extensively used microalgae in aquaculture, both for rotifer growth and pre-enrichment, and for green water treatment (GWT). Our trials with Provifeed^TM Nannochloropsis have shown that the rotifer growth and egg percentage of the rotifers is better than with artificial diets. On top of that the water quality is higher and cleaning of the system is less intensive than with the artificial diets.

In hatcheries of seabass and seabream our freeze dried Nannochloropsis is used as a safe and ready-to-use backup for the in house cultivated microalgae. A substitution of live algae with freeze dried biomass is possible without influencing digestibility, performance of the larvae and water quality.

Isochrysis T-ISO is a marine alga used in green water treatment in shrimp hatcheries and for rotifer enrichment with DHA.  The high quality and standardized composition of Provifeed^TM Isochrysis resulted in significantly higher survival rates in the hatcheries. Shrimp hatcheries that used the freeze dried powder from d0-d3 at 5g/d for 1 mio larvae had between 10 and 20% lower mortality rates during the cycli with Provifeed^TMisochrysis than during cycli where home grown microalgae in combination with artificial products were used.