PROTEIN AND LIPID CONTENTS OF GREEN SEAWEED Ulva flexuosa CULTIVATED IN DIFFERENT ENVIRONMENTAL CONDITIONS
The seaweeds, also known as macroalgae, can be used in aquafeeds as a viable alternative for conventional ingredients. The nutritional content of macroalgae can be vary mainly by species, seasons, nutrient availability and cultivation environment. This study purpose was to investigate the differences in crude protein and crude fat contents between Ulva flexuosa raised in shrimp production biofloc wastewater and seawater culture systems.
The green macroalgae U. flexuosa was cultivated in biofloc wastewater for 15 days while the seawater samples were taken from macroalgae lab at EMA, FURG (Cassino - R io Grande) . After cultivation studies, t he harvested algal biomass was first washed under freshwater and placed in an drying oven for 24 hours, at 60º C to prevent lipid oxidation. After, t he dried U. flexuosa biomass was grounded and the crude fat content was determinated by Soxhlet method while crude protein was determinated by Kjhedal titration method . The analyzes were done in triplicates.
The results showed that the macroalgae raised in biofloc system had more crude protein and fat contents than the macroalgae raised in seawater systems. This increase can be explained by the difference in illuminosity and avaliable nutrients between the two environments where the seaweeds were cultivated. The first is related to the high turbidity and solids level of the biofloc system compared to clear seawater cultivation conditions. Macroalgae tend to counterbalance the effects of low light by increasing their pigments and storing nitrogen in their tissue. As well as the high level of nitrogen in the form of ionized ammonia (NH4) and nitrate (NO3 ) in water provides an increase in algae protein content.
With the present study was possible to determinate that cultivating Ulva flexuosa in biofloc wastewater can enhance crude protein content and crude fat content. Despite that further studies are needed to ev aluate the utilization of these nutrients in aquatic organisms.
