Roberto Bianchini Derner

There is a notable lack of standardised and validated protocols for evaluating the potential of aquaculture effluents as culture media for microalgae. This study addresses this gap by developing and validating a comprehensive protocol for assessing the suitability of aquaculture effluents for microalgal production. The protocol was designed and standardised based on effluent characterisation, effluent pre-treatment, standardised inoculation, assessment of microalgal growth performance, and evaluation of nutrient removal. Validation was conducted through the cultivation of Phaeodactylum tricornutum in biofloc technology (BFT) shrimp (Penaeus vannamei) effluent, demonstrating the protocol’s reliability, robustness, and adaptability across media with varying nutrient profiles. The approach effectively identified nitrate and orthophosphate removal patterns of up to 97.34 ± 2.15% and 87.88 ± 1.61%, respectively, in culture media containing 100% shrimp effluent, while providing consistent and accurate growth performance data across different treatments. The treatment containing 100% shrimp effluent achieved a maximum cell density of 8488 ± 772 (×10⁴ cells mL⁻¹). As the proposed framework is based on broadly applicable performance indicators, it provides a methodological basis that can be adapted for evaluating other aquaculture effluents, microalgal species, and cultivation systems. However, additional validation under these conditions is required before broader application can be confirmed.

Wheat (Triticum aestivum) is an important crop produced worldwide. Natural or synthetic products including phytostimulants, biofertilisers, biostimulants, bioregulators or phytoprotectors have been developed over the years. The objective of this study was to evaluate the effects of foliar application of micronutrients (essential minerals), growth regulators, extracts of the microalga Porphyridium cruentum and their mixtures on variables related to the growth and production of wheat (height of the plants at harvest, number of tillers per plant, weight of 1000 grains, pod length and yield). The experiment consisted of randomised blocks with four replications, consisting of 16 treatments (control, Zn, B, Cu, Mn, Zn+Cu+B+Mn, indolebutyric acid (AIB), 6-benzylaminopurine (BAP), Zn+Cu+B+Mn+AIB+BAP, P. cruentum freeze-dried polysaccharide (PS), P. cruentum freeze-dried material (FM), Zn+Cu+B+Mn+PS+FM, AIB+BAP+FM+gibberellic acid (GA), commercial-B, commercial-A and commercial-E). The single foliar application of micronutrients, commercial products containing micronutrients, growth regulators (indolbutyric acid, 6-bezylaminopurine, gibberellic acid and their mixtures), freeze-dried polysaccharide and biomass of P. cruentum, and mixtures of micronutrients and growth regulators did not potentiate the development and productivity of the wheat crop. The average height of wheat plants at harvest was 77.81 cm and ranged from 80.05 cm when the comercial-E product was applied to 74.43 cm with the application of P. cruentum polysaccharide extract at a dose of 62 g ha-1, which resulted in lower crop yield, although the difference was not significant. Additionally, the individual application of the P. cruentum polysaccharide extract did not significantly influence on plant growth.

The ability of diatoms to adapt to variable light conditions such as photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) is crucial for their survival and ecological role. The study aimed to investigate how different doses of UVR regulate the photoprotection mechanism in Phaeodactylum tricornutum. Five treatments were established: Control (PAR only), PAR + UVR D_6h (17.5 W m^− 2, 6 h, 378 KJ m^− 2), PAR + UVR 2D_6h (35 W m^− 2, 6 h, 756 KJ m^− 2), PAR + UVR 2D_12h (17.5 W m^− 2, 12 h, 756 KJ m^− 2), and PAR + UVR 4D_12h (35 W m^− 2, 12 h, 1.512 KJ m^− 2). The growth of P. tricornutum was significantly affected by UVR doses, with a growth pattern of 42–55% below the control (PAR only). Increasing the UVR dose also had negative effects on photosynthesis parameters and the levels of chlorophyll-a and fucoxanthin. The de-epoxidation state showed a high rate in treatments subjected to higher UVR doses, promoting an attempt to activate cellular protection mechanisms. In the transcriptional genes related to the xanthophyll cycle, a reduction in transcript levels of ZEP1 and ZEP2 genes was observed in PAR + UVR treatments, including a reduction up to 75% at 72 h of exposure. Also, an increase in transcript levels of VDE and VDL1 genes was observed for treatments with the same UVR dose, reaching about 9-fold increase for the 2D_12h dose and 10-fold increase for the 2D_6h dose, both at 72 h, suggesting a modification in the cell’s ability to respond to UVR light stress.

Algae are known for their rich nutrients, which can enhance productivity of agricultural crops, making them valuable biostimulants. However, the use of microalgae for this purpose is still in its early stages, and there have been no studies conducted on lupine crops in Brazil so far. This study aimed to investigate the impact of microalgae extracts on the growth and productivity of white lupine. The experiment included four different microalgae extracts (Limnospira platensis, Nannochloropsis oculata, Tetradesmus obliquus, and Chaetoceros muelleri), applied either once or twice, along with a control group. The results showed that there was no interaction between the number of applications and the type of microalgae extract applied via foliar application in white lupine crops. The microalgae extracts did not have a significant impact on the 100-grain weight and yield of white lupine crops. The average height of white lupine plants at harvest was 117.04 cm, regardless of the treatment. However, there was a significant increase (13.12%) in the number of seeds per pod of white lupine with a single application of microalgae extract, regardless of the specific extract used. The height of the white lupine plants was not affected by the treatments during both the vegetative and reproductive phases. Further research is needed to optimise the bioactive extraction process, identify metabolites with biostimulant potential in the extracts, and determine the most effective application method (soil, seed, or foliar), as well as the optimal timing and frequency of foliar applications based on the crop's phenological stages.

The present study aimed to chemically profile the hydroalcoholic extracts from the microalgae (MEs) Nannochloropsis oculata, Phaeodactylum tricornutum, Tetradesmus obliquus, and Tetraselmis tetrathele and evaluate their effects on the development of Colletotrichum lindemuthianum and anthracnose symptoms, as well as on the initial growth of bean plants. For this, MEs were analyzed using UPLC coupled with a mass spectrometer, allowing the identification of peaks and annotation of potential metabolites. Fungal mycelial growth was assessed seven days after inoculation, and conidial germination was measured 72 h after incubation, using ME concentrations of 0, 0.1, 0.5, and 1.0 mg·mL⁻¹. Bean seeds of the IPR Uirapuru cultivar were sown and treated with 3 mL of extracts at four time points: at sowing and 72 h after each previous treatment. After 11 days of cultivation in a growth chamber, the plants were divided into two groups: one for anthracnose control assessment and the other for evaluating growth promotion by MEs. Plant length as well as fresh and dry weights of shoots and roots were determined, leaf pigments were quantified, and anthracnose severity was assessed using a diagrammatic scale. The UPLC analysis identified 32 compounds in the extracts of the four microalgae, belonging to different chemical and functional groups, with lipids being the most significant fraction. The extracts exhibited variability and diversity in chemical composition depending on the microalgal species. MEs did not affect mycelial growth yet increased the germination of C. lindemuthianum conidia, regardless of the dose or species used. Anthracnose severity was not affected by the microalgae extracts. Regarding growth promotion, the extracts showed varying effects but generally increased shoot and root length, fresh biomass, and leaf pigment content.

The aquafeed industry evolved alongside fish farming, utilizing scientific and technological advancements to incorporate a variety of feed additives, supplements, and alternative ingredients in the nutrition and feeding of fish in aquaculture. These advances played a significant role in improving the production, health, and welfare of farmed fish. Recent research in Brazil highlighted the importance of using fish feed additives, such as vitamins, minerals, and amino acids, to ensure that farmed fish receive all the necessary nutrients for growth and health. Functional additives can enhance the immune system, boosting disease resistance and promoting the overall health of fish. Antimicrobial and antiparasitic additives help prevent and treat infections and infestations, reducing the occurrence of disease outbreaks. Additionally, some additives improve feed digestibility, leading to better nutrient absorption and reduced feed requirements. Overall, nutritional strategies are essential for optimizing fish farming practices in Brazil and globally, promoting fish health and sustainability in the industry. This review emphasizes the significance of certain additives, supplements, and ingredients strategically incorporated into experimental feeds for research in Brazilian fish farming. It also underscores the necessity for ongoing research. There is a noticeable trend towards developing more sustainable and efficient feeds, which is essential for the future of sustainable aquaculture. The goal is to minimize environmental impacts while maintaining economic viability in aquaculture operations.