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- Incorporation of defatted microalgal biomass (Tetraselmis sp. CTP4) at the expense of soybean meal as a feed ingredient for juvenile gilthead seabream (Sparus aurata)Publication . Pereira, Hugo; Sardinha, Manuel; Santos, Tamára; Gouveia, Luisa; Barreira, Luísa; Dias, Jorge; Varela, JoãoABSTRACT: The forecasted growth of the aquaculture sector requires the use of novel and sustainable ingredients in aquaculture feeds. A study was undertaken to evaluate the effect of a 10% incorporation of defatted microalgal biomass (DMB) of Tetraselmis sp. CTP4, used at the expense of dehulled solvent-extracted soybean meal (SBM), on the growth performance, nutrient digestibility and physiological response to confinement stress in gilthead seabream juveniles. The trial comprised two dietary treatments: a control diet (CTRL) with relatively high levels of marine-derived proteins and 10% SBM; and a test diet (DMB10) with the incorporation of 10% DMB at the expense of SBM, while maintaining a fair constancy of all other ingredients. Triplicate groups of 30 fish, with a mean initial body weight of 6.0 ± 0.2 g were fed the experimental diets for 61 days. At the end of the trial, fish tripled their initial body weight, but the overall growth performance criteria (final body weight, daily growth index, feed conversion ratio and protein efficiency ratio), whole-body composition and nutrient retention were not significantly affected by the dietary treatments (p > 0.05). The DMB10 diet showed a significantly higher apparent digestibility coefficients (ADC) of dry matter, energy and phosphorus (p < 0.05). When measured as an isolated feed ingredient, the DMB had an ADC of protein, fat, energy and phosphorus of 87.9, 85.3, 75.5 and 41.4%, respectively. After an acute confinement stress test, fish fed with DMB10 diet displayed a significantly lower plasma cortisol response (120 ± 23 ng/mL) than those fed with the control diet (160 ± 33 ng/mL) (p < 0.05). Overall results showed that DMB, issued from biorefinery processes, could potentially spare the use of soybean meal in aquaculture feeds, contributing towards a reduction of the current protein deficit in the European market.
- Scale-up and large-scale production of Tetraselmis sp CTP4 (Chlorophyta) for CO2 mitigation: from an agar plate to 100-m(3) industrial photobioreactorsPublication . Pereira, Hugo; Páramo, Jaime; Silva, Joana; Marques, Ana; Barros, Ana; Maurício, Dinis; Santos, Tamára; Schulze, Peter; Barros, Raúl; Gouveia, Luisa; Barreira, Luísa; Varela, JoãoABSTRACT: Industrial production of novel microalgal isolates is key to improving the current portfolio of available strains that are able to grow in large-scale production systems for different biotechnological applications, including carbon mitigation. In this context, Tetraselmis sp. CTP4 was successfully scaled up from an agar plate to 35-and 100-m(3) industrial scale tubular photobioreactors (PBR). Growth was performed semi-continuously for 60 days in the autumn-winter season (17th October -14th December). Optimisation of tubular PBR operations showed that improved productivities were obtained at a culture velocity of 0.65-1.35 m s(-1) and a pH set-point for CO2 injection of 8.0. Highest volumetric (0.08 +/- 0.01 g L-1 d(-1)) and areal (20.3 +/- 3.2 g m(-2) d(-1)) biomass productivities were attained in the 100-m(3) PBR compared to those of the 35-m(3) PBR (0.05 +/- 0.02 g L-1 d(-1) and 13.5 +/- 4.3 g m(-2) d(-1), respectively). Lipid contents were similar in both PBRs (9-10% of ash free dry weight). CO2 sequestration was followed in the 100-m(3) PBR, revealing a mean CO2 mitigation efficiency of 65% and a biomass to carbon ratio of 1.80. Tetraselmis sp. CTP4 is thus a robust candidate for industrial-scale production with promising biomass productivities and photosynthetic efficiencies up to 3.5% of total solar irradiance.