Nuevos registros de Algas verdes (Chlorophyta) de ríos y arroyos serranos de la provincia de Córdoba, Argentina

El objetivo de este trabajo fue ampliar el conocimiento de las Chloroplastida de los tributarios del embalse San Roque (ríos San Antonio y Cosquin, arroyos Las Mojarras y Los Chorrillos) y el embalse La Quebrada (arroyos Colanchanga y Los Hornillos). Las muestras fueron recolectadas estacionalmente durante los años 2014 a 2016. Se identificaron un total de 66 taxones: Chlorophyceae (39), Zygnematophyceae (22), Trebouxiophyceae (3) y Ulvophyceae (2). La mayor riqueza de especies ocurrió en primavera y el rio San Antonio fue el tributario que presentó mayor número de taxones. Se mencionan especies indicadoras de eutrofia como Monoraphidium griffithii; Actinastrum hantzschii, Monactinus simplex, Nephrocytium agardhianum, Scenedesmus subspicatus, Staurastrum leptocladum, Closterium aciculare y a Phacotus lenticularis, especie indicadora de ambientes con carbonato de calcio.

Organic onion biofortification using microalgae and humic acid

Biofortification can be understood as a strategy to raise nutrients levels in vegetables edible structures, which can positively interfere in human diet. Biofertilizers are an interesting option in alternative production systems, as they can increase food nutritional quality and contribute to plant development, while aiding environment sustainability as natural products. The use of microalgae and humic acid as biofertilizers points to improvements in nutrients and biomolecules content in plants, however, their combined application is still unexplored. In that scenario, it was carried a study with onions about the influence of applications via root immersion in microalgae Scenedesmus subspicatus (Sc) and humic acid (HA) solutions, analyzing possible alterations of macro and micronutrients, total sugars, reducing sugar, free total amino acids, , total soluble solids, soluble proteins and antioxidant capacity in the bulbs. Treatments consisted of one minute seedlings roots immersion from two onion cultivars in solutions containing microalgae and humic acid, and then transplanted to organic system field. There were used three concentrations: control, 0.3 g L-1 Sc + 0.3 g L-1 HA (3SH) and 0.6 g L-1 Sc + 0.6 g L-1 HA (6SH). Results show that the treatments with microalgae with humic acid association were able to increase the content of N, carbohydrates and soluble proteins, also elevating antioxidant activity in onion bulbs.

Biofixation of Air Emissions and Biomass Valorization – Evaluation of Microalgal Biotechnology

This research appraised the simultaneous biofixation of carbon dioxide (CO 2 ) and nitric oxides (NO x ) by microalgae species Chlorella vulgaris , Haematococcus pluvialis , and Scenedesmus subspicatus . The experimental design was established by five treatments with gas concentrations between control – 0.04% of CO 2 , 5 to 15% of CO 2 , and 30 to 100 ppm of NOx. Parameters such as pH, growth, productivity, lipids, protein, carbon/ nitrogen ratio, and astaxanthin were evaluated. For all species, the maximal growth was achieved with 5% of CO 2 and 30 ppm of NO x . Regarding protein content, for all the three species, better results were obtained at higher concentrations of CO 2 and NOx. These results prove the microalgae capacity for CO 2 and NO x biofixation and reuse of biomass as a source of high value-added products, such as lipids, proteins, and astaxanthin. These findings support the indication of these species for flue gas treatment process and use in biorefineries systems.

Crescimento populacional de Moina sp. alimentadas com diferentes dietas para uso na larvicultura e aquariofilia

O objetivo da pesquisa foi avaliar o crescimento populacional de Moina sp. alimentadas com quatro dietas por um período de 14 dias. A densidade inicial foi de uma moina adulta/L-1 de água. As moinas foram cultivadas em 20 recipientes plásticos transparentes com volume útil de 20L-1. Foi verificada diariamente a temperatura da água, pH, oxigênio dissolvido e condutividade elétrica. Foram testados quatro tipos de dietas e coletadas diariamente cinco amostras de um litro, de cada tanque de cultivo, onde as mesmas foram filtradas em peneira de 800µ e os organismos colocados num recipiente de 50mL com ajuda de uma pisseta, para contagem total sob estereomicroscópio com aumento de até 25x. Os parâmetros populacionais avaliados foram: densidade máxima de organismos; dia de máxima densidade; taxa de crescimento específico; tempo de duplicação e rendimento. Os resultados obtidos foram submetidos ao teste F para análise de variância e análises de regressão linear com o auxílio do pacote estatístico SAS®. Os parâmetros físico-químicos de temperatura, pH, oxigênio dissolvido e condutividade elétrica, se mantiveram dentro do intervalo recomendado para o cultivo. Entretanto, para os parâmetros populacionais de densidade máxima (dieta 4) e taxa de crescimento populacional (dieta 3), apresentaram diferença estatística em relação as outras dietas avaliadas. O parâmetro Tempo de duplicação (Td) não apresentou diferença significativa entre as dietas avaliadas. A dieta mais indicada para o cultivo de Moina sp. foi o tratamento 4 que continha em sua composição Microalga Scenedesmus subspicatus, ração para peixe fermentada, Aptamil premium e Levedura (Saccharomyces cerevisiae).

ESCOLHA DAS ESPÉCIES BIOMONITORAS E EFLUENTE TÊXTIL

O presente artigo analisa três organismos para verificar qual deve ser empregado como biomonitor (método bottom-up). A partir da análise das seguintes espécies: Aliivibrio fischeri, Daphnia magna e Scenedesmus subspicatus. Foram verificadas as características: taxonômia bem definida, tamanho da espécie, identificação por não especialistas, distribuição geográfica, ser abundante, baixa variabilidade ecológica/gênica, possibilidade de uso em laboratório, baixa mobilidade, longo ciclo de vida e característica ecológica bem conhecida. A partir desta, a Daphnia magna foi a que apresentou melhor pontuação nos atributos analisados. Este organismo já é um biomonitor amplamente utilizado para o monitoramento de efluentes têxteis, visto que as análises dos demais organismos podem sofrer interferência da coloração do efluente.

Evaluation of antioxidant and antibacterial capacity of green microalgae Scenedesmus subspicatus

Microalgae are considered one of the most promising raw materials for the development of high value products for pharmaceuticals, nutraceuticals, and cosmetic industries, as well as being potential sources of protein, vitamins, and minerals for human consumption. Hence, the present research focuses extraction of antioxidant and antimicrobial compounds from Scenedesmus subspicatus using solvents of different polarities. Different solvents such as ethanol, methanol, butanol, acetone, dimethyl sulfoxide, and water were used to extract compounds from the green microalgae S. subspicatus and then they were examined for phytochemical screening, antioxidant activity, and antimicrobial properties. In vitro free radical quenching and total antioxidant activity of extracts were investigated with 1,1-diphenyl-2-picryl hydrazyl and compared with catequin and gallic acid as positive controls. The antimicrobial activity was evaluated in gram-negative and gram-positive bacteria. Aqueous extracts and dimethyl sulfoxide presented better performance in phytochemical analysis. This result showed consistency in the sequential tests. The antioxidant activity was also better using the two solvents cited above. The extracts acetone, water, and dimethyl sulfoxide showed ability to inhibit the growth of Bacillus subtilis. However, only dimethyl sulfoxide inhibited the growth of Klebsiella pneumoniae and Escherichia coli. Use of the aqueous extract, proven its effectiveness, is an economic protocol and avoids the use of toxic substances.

Effects from log-yard stormwater runoff on the microalgae Scenedesmus subspicatus

The effects posed by stormwater runoff from an industrial log-yard on the microalgae Scenedesmus subspicatus have been investigated. The effects of stormwater runoff sampled during two rain events on the microalgae were determined in different concentrations (% v:v). The test organisms were exposed to the stormwater runoff 96h and the percentage change in growth rates in relation to a control culture were measured at exposure times of 24h, 48h, 72 and 96h. Whereas the runoff from the first rain event posed in most cases growth stimulatory effects, the runoff from the second rain event inhibited algae growth. Differences in runoff physico-chemical characteristics combined with the hydrological factors of each rain event explained these opposite effects. The occurrence of the “first flush” phenomenon was studied and the results confirmed such occurrences in the second rain event. On the basis of normalized inhibitory effects and runoff volume, it was found that 42, 51 and 50% of the inhibitory effects during exposures of 24, 48 and 72h were associated with the initial 4% of the total discharged volume. To conclude it can be stated that since the stormwater runoff of only 2 rain events posed negative effects on the test organisms, the potential environmental threats posed by these waters during the entire hydrological year needs to be better understood in order to propose an adequate management program.