Application of 1H HR-MAS NMR-Based Metabolite Fingerprinting of Marine Microalgae.

Natural products from the marine environment as well as microalgae, have been known for the complexity of the metabolites they produce due to their adaptability to different environmental conditions, which has been an inexhaustible source of several bioactive properties, such as antioxidant, anti-tumor, and antimicrobial. This study aims to characterize the main metabolites of three species of microalgae (Nannochloropsis oceanica, Chaetoceros muelleri, and Conticribra weissflogii), which have important applications in the biofuel and nutrition industries, by 1H High-resolution magic angle spinning nuclear magnetic resonance (1H HR-MAS NMR), a method which is non-destructive, is highly reproducible, and requires minimal sample preparation. Even though the three species were found in the same ecosystem and a superior production of lipid compounds was observed, important differences were identified in relation to the production of specialized metabolites. These distinct properties favor the use of these compounds as leaders in the development of new bioactive compounds, especially against environmental, human, and animal pathogens (One Health), and demonstrate their potential in the development of alternatives for aquaculture.

Chemical Profile and Antimicrobial Activity of the Marine Diatom Chaetoceros muelleri.

Microalgae, due to its rapid growth, low nutritional requirements, and versatility of adaptation to different environmental conditions, has aroused the biotechnological interest, synthesizing novel molecules with antioxidant, anticoagulant, anti-inflammatory, antitumor, and antimicrobial activities. In this sense, we carried out the bioprospection of Chaetoceros muelleri, a marine diatom employed in aquaculture, as a candidate to the development of new drugs for the treatment of bacterial infections. The chemical profile of extracts in different solvents (hexane, chloroform, methylene chloride, ethyl acetate, methanol, and acetone) were analyzed by 1 H-NMR. The hexane extract was the most active against all bacteria species tested, including Mycobacterium tuberculosis, with a minimum inhibitory concentration of 100 µg/ml. Contrarily, the methanol extract was inactive against all tested microorganisms and, in addition, was the only one with IC50 >800 µg/mL, showing no cytotoxicity in VERO cell lines. All other extracts showed antibacterial potential and IC50 values varying between 267.58 and 142.47 µg/ml. The fact that C. muelleri is a microalga easily grown on bioreactors on a large scale may promote its biotechnological use, especially as scaffolds for the development of new compounds against bacterial species of clinical and public health interest.

Inhibition of Enzymatic and Oxidative Processes by Phenolic Extracts from Spirulina sp. and Nannochloropsis sp.

This study investigates the capacity of phenolic extracts from microalgae Nannochloropsis sp. and Spirulina sp. to inhibit enzymes and free radical activities, intending to find an innovative way to slow down food damage. HPLC-UV and LC-MS/MS served to determine and confirm, respectively, the phenolic acid profiles in the soluble methanolic (free phenolic) and ethanolic (conjugated phenolic) fractions, and after hydrolysis (bound phenolic fractions). Different procedures measured the antioxidant activity of the extracts to estimate the minimal concentration for the protective effect, stability and versatility of activity. The ability to inhibit the oxidative process (ABTS and DPPH), α-amylase and peroxidase activities were estimated as specific inhibition (%/(min·µg)) for better comparison between the phenolic sources. The phenolic acid mass fractions in the free phenolic extracts from Spirulina sp. and Nannochloropsis sp. were 628 and 641 µg/g, respectively. Phenolic extract from Nannochloropsis sp. showed the highest value of ABTS inhibition (1.3%/(min·µg)) and highest inhibition of peroxidase activity (0.4%/(min·µg)). The extract from Spirulina sp. was a better inhibitor of α-amylase activity (0.07%/(min·µg)). Therefore, the phenolic extracts from the edible microalgae may be applied in food industry as natural protector against endogenous and exogenous hydrolytic and oxidative processes.

Use of natural pH variation to increase the flocculation of the marine microalgae Nannochloropsis oculata.

Microalgae is largely used in aquaculture as feed. More recently, these microorganisms have been considered as an important feedstock for biodiesel production. However, the concentration of produced biomass represents a large parcel of production costs. In this study, we have evaluated the influence of natural pH variation of culture medium, caused by photosynthetic activity, on the flocculation of the marine microalgae Nannochloropsis oculata. Experiments were conducted with the same culture with different pH values (8.5 and 9.6), obtained after exposing the cells to different light conditions. For each pH value, different treatments were composed by adding 0, 5, 10, and 30 mM of NaOH and the flocculant Flopam® (FO4800 SH) at concentrations of 0, 0.5, 1, and 5 ppm. Higher flocculation efficiencies were obtained for the culture with pH 9.6 in comparison to 8.5 for the same NaOH and Flopam concentrations. Lower concentrations of base and flocculant were needed for flocculating the culture in higher pH, representing an economy of 20 % in the costs of crop harvesting.

Bacterial community composition and physiological shifts associated with the El Niño Southern Oscillation (ENSO) in the Patos Lagoon estuary.

The Patos Lagoon estuary is a microtidal system that is strongly regulated by atmospheric forces, including remote large-scale phenomena such as the El Niño Southern Oscillation (ENSO), which affects precipitation patterns in the region. In this study, we investigated whether the bacterial community composition (BCC), community-level physiological profiles (CLPP), and a set of environmental variables were affected by the transition from a moderate El Niño to a strong La Niña event (June 2010 to May 2011). We identified two distinct periods: a period following El Niño that was characterized by low salinity and high concentrations of NO3(-) and PO4(-3) and low molecular weight (LMW) substances and a period following La Niña during which salinity, temperature, and transparency increased and the concentrations of nutrients and LMW substances decreased. The BCC and CLPP were significantly altered in response to this transition. This is the first study addressing the effect of ENSO on bacteria at the community level in an estuarine system. Our results suggest that there is a link between ENSO and bacteria, indicating the role of climate variability in bacterial activities and, hence, the cycling of organic matter by these microorganisms.

Stability of bacterial composition and activity in different salinity waters in the dynamic Patos Lagoon estuary: evidence from a lagrangian-like approach.

We employed a Lagrangian-like sampling design to evaluate bacterial community composition (BCC--using temporal temperature gel gradient electrophoresis), community-level physiological profiles (CLPP--using the EcoPlate™ assay), and influencing factors in different salinity waters in the highly dynamic Patos Lagoon estuary (southern Brazil) and adjacent coastal zone. Samples were collected monthly by following limnetic-oligohaline (0-1), mesohaline (14-16), and polyhaline (28-31) waters for 1 year. The BCC was specific for each salinity range, whereas the CLPPs were similar for mesohaline and polyhaline waters, and both were different from the limnetic-oligohaline samples. The limnetic-oligohaline waters displayed an oxidation capacity for almost all organic substrates tested, whereas the mesohaline and polyhaline waters presented lower numbers of oxidized substrates, suggesting that potential activities of bacteria increased from the polyhaline to oligohaline waters. However, the polyhaline samples showed a higher utilization of some simple carbohydrates, amino acids, and polymers, indicating a shortage of inorganic nutrients (especially nitrogen) and organic substrates in coastal saltwater. The hypothesis of bacterial nitrogen limitation was corroborated by the higher Nuse index (an EcoPlate™-based nitrogen limitation indicator) in the polyhaline waters and the importance of NO(2)(-), NO(3)(-), low-molecular-weight substances, and the low-molecular-weight:high-molecular-weight substances ratio, indicated by the canonical correspondence analyses (CCAs). Our results demonstrate the important stability of microbial community composition and potential metabolic activity in the different water salinity ranges, which are independent of the region and time of the year of sample collection in the estuary. This is a quite unexpected result for a dynamic environment such as the Patos Lagoon estuary.

Natural occurrence of White spot syndrome virus and Infectious hypodermal and hematopoietic necrosis virus in Neohelice granulata crab.

White spot syndrome virus (WSSV) and Infectious hypodermal and hematopoietic necrosis virus (IHHNV) are two infectious agents associated to economic losses in shrimp aquaculture. As virus spread occurs through vectors and hosts, this study sought to verify the presence of WSSV and IHHNV in Neohelice granulata crab from Lagoa dos Patos estuary in Brazil and nearby shrimp farms. DNA extractions were performed with phenol/chloroform protocol. Molecular diagnosis was carried out by nested PCR for WSSV and one-step PCR for IHHNV. Results showed the presence of WSSV on crabs of both Lagoa dos Patos and farms, while IHHNV was found only on crabs collected in estuary. This is the first study to report IHHNV presence in N. granulata. Moreover, as analyzed crabs had no clinical symptoms or showed in situ mortality, we suggest its use as a bioindicator for virus occurrence in aquatic environments.

First report of White spot syndrome virus in farmed and wild penaeid shrimp from Lagoa dos Patos estuary, southern Brazil

In this study, we detected White spot syndrome virus (WSSV) in wild Farfantepenaeus paulensis collected in the Lagoa dos Patos estuary and cultivated Litopenaeus vannamei. This is the first report of WSSV in F. paulensis from Lagoa dos Patos and farmed L. vannamei shrimps in Rio Grande do Sul.

First report of White spot syndrome virus in farmed and wild penaeid shrimp from lagoa dos patos estuary, southern brazil.

In this study, we detected White spot syndrome virus (WSSV) in wild Farfantepenaeus paulensis collected in the Lagoa dos Patos estuary and cultivated Litopenaeus vannamei. This is the first report of WSSV in F. paulensis from Lagoa dos Patos and farmed L. vannamei shrimps in Rio Grande do Sul.

Efeito da densidade de estocagem sobre o biofilme e o desempenho de pós-larvas do camarão-rosa FarfantePenaeus paulensis cultivadas em gaiolas / Effect of stocking density on the biofilm and the performance of post-larvae of the pink shrimp FarfantePenaeus paulensis in cages

O objetivo deste estudo foi analisar a influência da densidade de estocagem na sobrevivência e no crescimento de pós-larvas de F. paulensis cultivadas em gaiolas durante a fase de berçário. Além disso, foram identificados e quantificados os principais microrganismos presentes no biofilme formado nos substratos artificiais colocados dentro das gaiolas. Foram usadas gaiolas com 4 m² de fundo e com substratos artificiais, nas densidades de 100, 200, 300, 400 e 500PL25 m-2. O experimento durou 35 dias. Observou-se uma relação negativa entre o aumento da densidade de estocagem de camarões e a sobrevivência e o crescimento destes. Foi observada uma preferência pelo consumo de diatomáceas cêntricas. A viabilidade técnica do cultivo de F. paulensis em gaiolas foi confirmada. O cultivo de F. paulensis em gaiolas na fase de berçário pode ser feito em densidades de até 400PL m-2, sem maiores perdas em sua sobrevivência e seu crescimento.